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in category plant biology

1,802 results found. For more information, click each entry to expand.

1721: The Brassica napus Wall-Associated Kinase-Like (WAKL) gene Rlm9 provides race-specific blackleg resistance
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Posted to bioRxiv 24 Oct 2019

The Brassica napus Wall-Associated Kinase-Like (WAKL) gene Rlm9 provides race-specific blackleg resistance
85 downloads plant biology

Nicholas J. Larkan, Lisong Ma, Parham Haddadi, Miles Buchwaldt, Isobel A.P. Parkin, Mohammad Djavaheri, M. Hossein Borhan

In plants, race-specific defense against microbial pathogens is facilitated by resistance (R) genes which correspond to specific pathogen avirulence (Avr) genes. This study reports the cloning of a blackleg R gene from Brassica napus (canola); Rlm9, which encodes a wall-associated kinase-like (WAKL) protein, a newly-discovered class of race-specific plant RLK resistance genes. Rlm9 provides race-specific resistance against isolates of Leptosphaeria maculans carrying the corresponding avirulence gene AvrLm5-9, representing only the second WAKL-type R gene described to date. The Rlm9 protein is predicted to be cell membrane-bound yet appears to have no direct interaction with AvrLm5-9. Rlm9 forms part of a distinct evolutionary family of RLK proteins in B. napus, and while little is yet known about WAKL function, the Brassica-Leptosphaeria pathosystem may prove to be a model system by which the mechanism of fungal avirulence protein recognition by WAKL-type R genes can be determined.

1722: Characterization of the virome of shallots affected by the shallot mild yellow stripe disease in France
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Posted to bioRxiv 17 Jun 2019

Characterization of the virome of shallots affected by the shallot mild yellow stripe disease in France
84 downloads plant biology

Armelle Marais, Chantal Faure, Sébastien Theil, Thierry Candresse

To elucidate the etiology of a new disease on shallot in France, double-stranded RNAs from asymptomatic and symptomatic shallot plants were analyzed by high-throughput sequencing (HTS). Contigs annotation, molecular characterization and phylogenetic analyses revealed the presence in symptomatic plants of a virus complex consisting of shallot virus X (ShVX, Allexivirus), shallot latent virus (SLV, Carlavirus) and two novel viruses belonging to the genera Carlavirus and Potyvirus, for which the names of shallot virus S (ShVS) and shallot mild yellow stripe associated virus (SMYSaV), are proposed. Complete or near complete genomic sequences were obtained for all these agents, revealing divergent isolates of ShVX and SLV. Trials to fulfill Koch’s postulates were pursued but failed to reproduce the symptoms on inoculated shallots, even though the plants were proved to be infected by the four viruses detected by HTS. Replanting of bulbs from SMYSaV-inoculated shallot plants resulted in infected plants, showing that the virus can perpetuate the infection over seasons. A survey analyzing 351 shallot samples over a four years period strongly suggests an association of SMYSaV with the disease symptoms. An analysis of SMYSaV diversity indicates the existence of two clusters of isolates, one of which is largely predominant in the field over years.

1723: Mapping of Quantitative Trait Loci for Traits linked to Fusarium Head Blight Symptoms Evaluation in Barley RILs
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Posted to bioRxiv 29 Aug 2019

Mapping of Quantitative Trait Loci for Traits linked to Fusarium Head Blight Symptoms Evaluation in Barley RILs
84 downloads plant biology

Piotr Ogrodowicz, Anetta Kuczyńska, Krzysztof Mikołajczak, Tadeusz Adamski, Maria Surma, Paweł Krajewski, Hanna Ćwiek-Kupczyńska, Michał Kempa, Michał Rokicki, Dorota Jasińska

Fusarium head blight (FHB) is a devastating disease in small grain cereals worldwide. The disease results in the reduction of grain yield and affects its quality. In addition, mycotoxins accumulated in grain are harmful to both humans and animals. It has been reported that response to pathogen infection may be associated with the morphological and developmental characteristics of the host plant, e.g. the earliness and plant height. Despite the many studies the effective markers for the selection of barley genotypes with increased resistance to FHB have not thus far been developed. Therefore, exploring the genetic relationship between agronomic traits (e.g. heading date or stem height) and disease resistance is of importance to the understanding of plant resistance via “diesease escape” or dwarf stature. The studied plant material consisted of 100 recombinant inbred lines (RIL) of spring barley. Plants were examined in field conditions (three locations) in a completely randomized design with three replications. Barley genotypes were artificially infected with spores of Fusarium before heading. Apart from the main phenotypic traits (plant height, spike characteristic, grain yield) the infected kernels were visually scored and the content of deoxynivalenol (DON) mycotoxin was investigated. A set of 70 Quantitative Trait Loci (QTLs) were detected through phenotyping of the mapping population in field condition and genotyping using a barley Ilumina iSelect platform with 9K markers. Six loci were detected for FHB index on chromosomes 2H, 3H, 5H and 7H. The region on the short arm of the 2H chromosome was detected in the current study, in which many QTLs associated with FHB- and yield-related characters were found. This study confirms that agromorphological traits are tightly related to the FHB and should be taken into consideration when breeding barley plants for FHB resistance.

1724: Electrophysiological characterization of AtAMT1;4, an extraordinarily high affinity ammonium transporter from Arabidopsis thaliana
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Posted to bioRxiv 28 Oct 2019

Electrophysiological characterization of AtAMT1;4, an extraordinarily high affinity ammonium transporter from Arabidopsis thaliana
84 downloads plant biology

Nino Bindel, Benjamin Neuhaeuser

In plants high affinity transport proteins mediate the essential transport of ammonium across membranes. In Arabidopsis thaliana six of these AMmonium Transporters (AMTs) are encoded on the genome. All of these show a unique expression pattern. While most AMTs are highly expressed in the root, AtAMT1;4 expression is limited to the pollen grains and the pollen tube. Here, we addressed the transport characteristics of AtAMT1;4 in the heterologous Xenopus laevis oocytes system. Two electrode voltage clamp measurements tagged AtAMT1;4 as an electrogenic high affinity ammonium transporter. The transport was saturable and showed extraordinarily high affinity for ammonium with a Km value lower than 10 μM.

1725: Novel insights into N-glycan fucosylation and core xylosylation in C. reinhardtii
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Posted to bioRxiv 25 Sep 2019

Novel insights into N-glycan fucosylation and core xylosylation in C. reinhardtii
84 downloads plant biology

Anne Oltmanns, Lara Hoepfner, Martin Scholz, Karen Zinzius, Stefan Schulze, Michael Hippler

Chlamydomonas reinhardtii N -glycans carry plant typical β1,2-core xylose, α1,3-fucose residues as well as plant atypical terminal β1,4-xylose and methylated mannoses. In a recent study, XylT1A was shown to act as core xylosyltransferase, whereby its action was of importance for an inhibition of excessive Man1A dependent trimming. N -Glycans found in a XylT1A/Man1A double mutant carried core xylose residues, suggesting the existence of a second core xylosyltransferase in C. reinhardtii . To further elucidate enzymes important for N -glycosylation, novel single knockdown mutants of candidate genes involved in the N -glycosylation pathway were characterized. In addition, double, triple and quadruple mutants affecting already known N -glycosylation pathway genes were generated. By characterizing N -glycan compositions of intact N -glycopeptides from these mutant strains by mass spectrometry, a candidate gene encoding for a second putative core xylosyltransferase (XylT1B) was identified. Additionally, the role of a putative fucosyltransferase was revealed. Mutant strains with knockdown of both xylosyltransferases and the fucosyltransferase resulted in the formation of N -glycans with strongly diminished core modifications. Thus, the mutant strains generated will pave the way for further investigations on how single N -glycan core epitopes modulate protein function in C. reinhardtii . Significance Statement Our data provide novel insights into the function of XylT1B and FucT in C. reinhardtii as N -glycan core modifying enzymes. In the course of our study, different mutants were created by genetic crosses showing either varying or a lack of N -glycan core modification, enabling comparative analyses in relation to single N -glycan core epitope and overall protein function in C. reinhardtii .

1726: Elevated CO2 and warming change the nutrient status and use efficiency of Panicum maximum Jacq.
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Posted to bioRxiv 03 Oct 2019

Elevated CO2 and warming change the nutrient status and use efficiency of Panicum maximum Jacq.
83 downloads plant biology

Juliana Mariano Carvalho, Renato de Mello Prado, Rafael Ferreira Barreto, Eduardo Habermann, Roberto Botelho Ferraz Branco, Carlos Alberto Martinez

Panicum maximum Jacq. ‘Mombaça’ (guinea grass) is a C4 forage grass widely used in tropical pastures for cattle feeding. In this study, we evaluated the isolated and combined effects of warming and elevated CO2 concentration \[CO2] during summer on the nutrient content, nutrient accumulation, nutrient use efficiency and growth of P. maximum under field conditions with adequate water supply. The temperature and [CO2] in the field were controlled by temperature free-air controlled enhancement and free-air CO2 enrichment systems, respectively. We tested two levels of canopy temperature: ambient temperature and 2°C above ambient temperature, as well as two levels of atmospheric [CO2]: ambient [CO2\] (aCO2) and 200 ppm above ambient CO2 (eCO2). The experiment was established in a completely randomised design with four replications, in a 2×2 factorial scheme. After the pasture establishment, plants were exposed to the treatments for 30 days, with evaluations at 9, 16, 23 and 30 days after the treatments started. Results were dependent on the time of the evaluation, but in the last evaluation (beginning of the grazing), contents of N, K, Mg and S did not change as a function of treatments, P decreased as a function of warming, in [aCO2] and [eCO2], and Ca increased under [eCO2] combined with warming. There was an increase in root dry mass under warming treatment. Combined treatment increased N, Ca and S accumulation without a corresponding increase in the use efficiency of these same nutrients, indicating that the fertiliser dose should increase in the next decades due to human-induced climate change. Our short-term results suggest that the combination of high [CO2] and temperature will increase P. maximum productivity and that the nutritional requirement for N, Ca and S will increase.

1727: Conifers exhibit a characteristic inactivation of auxin to maintain tissue homeostasis
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Posted to bioRxiv 01 Oct 2019

Conifers exhibit a characteristic inactivation of auxin to maintain tissue homeostasis
83 downloads plant biology

Federica Brunoni, Silvio Collani, Ruben Casanova.Saez, Jan Simura, Michal Karady, Markus Schmid, Karin Ljung, Catherine Bellini

Dynamic regulation of the levels of the natural auxin, indol-3-acetic acid (IAA), is essential to coordinate most of the physiological and developmental processes and responses to environmental changes. Oxidation of IAA is a major pathway to control auxin concentrations in Arabidopsis and, along with IAA conjugation, to respond to perturbation of IAA homeostasis. However, these regulatory mechanisms are still poorly investigated in conifers. To reduce this gap of knowledge, we investigated the different contribution of the IAA inactivation pathways in conifers. Mass spectrometry-based quantification of IAA metabolites under steady state conditions and after perturbation was investigated to evaluate IAA homeostasis in conifers. Putative Picea abies GH3 genes (PaGH3) were identified by a comprehensive phylogenetic analysis including Arabidopsis and basal land plants. Auxin-inducible PaGH3 genes were identified by expression analysis and their IAA-conjugating activity was explored. Compared to Arabidopsis, oxidative and conjugative pathways differentially contribute to reduce IAA levels in conifers. We demonstrated that the oxidation pathway plays a marginal role in controlling IAA homeostasis in spruce. On the other hand, an excess of IAA rapidly activates GH3-mediated irreversible conjugation pathways. Taken together, these data indicate that a diversification of IAA inactivation mechanisms evolved specifically in conifers.

1728: Pollen morphology of Polish species from the genus Rubus L. (Rosaceae) and its systematic importance
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Posted to bioRxiv 13 Aug 2019

Pollen morphology of Polish species from the genus Rubus L. (Rosaceae) and its systematic importance
83 downloads plant biology

Kacper Lechowicz, Dorota Wrońska-Pilarek, Jan Bocianowski, Tomasz Maliński

The genus Rubus L. (Rosaceae) has as yet not been investigated satisfactorily in terms of palynology. This genus is taxonomically very difficult due to the large number of species and problems with their delimitation, as well as very different distribution areas of particular species. The aim of this study was to investigate pollen morphology and for the first time the ranges of intrageneric and interspecific variability of Rubus species, as well as verify the taxonomic usefulness of these traits in distinguishing studied taxa from this genus. They were analysed for 11 quantitative pollen characteristics and the following qualitative ones: exine ornamentation, pollen outline and shape, as well as bridge structure. Analyses were conducted on a total of 1740 pollen grains, which represent 58 blackberry species belonging to a majority of subgenera and all the sections and series found in Poland. The diagnostic characters included exine ornamentation (exine ornamentation type, width and direction of grooves and striae, number and diameter of perforations) and length of the polar axis (P). The arrangement of the examined species on the dendrogram does not corroborate division of the genus Rubus into subgenera, sections and series currently adopted in taxonomy. The lack of dependence may result from apomixis observed in Rubus, which could reduce natural variability. Pollen features should be treated in taxonomy as auxiliary, because they fail to differentiate several (10) individual species, while the other ones create groups with similar pollen traits.

1729: Identification of chloroplast envelope proteins with critical importance for cold acclimation
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Posted to bioRxiv 21 Oct 2019

Identification of chloroplast envelope proteins with critical importance for cold acclimation
82 downloads plant biology

Oliver Trentmann, Timo Mühlhaus, David Zimmer, Frederik K Sommer, Michael Schroda, Ilka Haferkamp, Isabel Keller, Benjamin Pommerrenig, H. Ekkehard Neuhaus

The ability of plants to cope with cold temperatures relies on their photosynthetic activity. This already demonstrates that the chloroplast is of utmost importance for cold acclimation and acquisition of freezing tolerance. During cold acclimation, the properties of the chloroplast change markedly. To provide the most comprehensive view of the protein repertoire of chloroplast envelope, we analysed this membrane system in Arabidopsis thaliana using MS-based proteomics. Profiling chloroplast envelope membranes was achieved by a cross comparison of protein intensities across plastid and the enriched membrane fraction both under normal and cold conditions. To address envelop localization, multivariable logistic regression models the probabilities for the classification problem. In total, we identified 38 envelope membrane intrinsic or associated proteins exhibiting altered abundance after cold acclimation. These proteins comprise several solute carries, such as the ATP/ADP antiporter NTT2 (substantially increased abundance) or the maltose exporter MEX1 (substantially decreased abundance). Remarkably, analysis of the frost recovery of ntt loss-of-function and mex1 overexpressor mutants confirmed that the comparative proteome is well suited to identify novel key factors involved in cold acclimation and acquisition of freezing tolerance. Moreover, for proteins with known physiological function we propose scenarios explaining their possible role in cold acclimation. Furthermore, spatial proteomics introduces a novel layer of complexity and enabled the identification of proteins differentially localized at the envelope membrane under the changing environmental regime.

1730: Soybean drought resilience: contributions of a brassinosteroid functional analogue.
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Posted to bioRxiv 22 Aug 2019

Soybean drought resilience: contributions of a brassinosteroid functional analogue.
82 downloads plant biology

Lucia Sandra Perez Borroto, Laila Toum, Atilio Pedro Castagnaro, Justo Lorenzo Gonzalez-Olmedo, Francisco Coll-Manchado, Bjorn Gunnar Viking Welin, Yamilet Coll-Garcia, Esteban Mariano Pardo

Drought is one of the most important causes of severe yield loss in soybean worldwide, threatening food production for the coming years. Phytohormones such as brassinosteroids can increase response to water deficit. However, natural brassinosteroids low stability precludes large-scale field application, challenging research and development of more stable and cost-effective analogues. Seeking functional analogues capable of improving plant drought-response, we investigated for the first time the effect of DI-31 in Arabidopsis and soybean. We found that, in A. thaliana, the DI-31 increased root growth, biomass accumulation, leaf number per plant, triggered antioxidant response and dose-dependent stomatal closure, requiring NADPH and peroxidase-dependent ROS production. In soybean, the relative water content, water use efficiency, biomass production and duration, root length, free proline, chlorophyll and carotenoid accumulation and enzymatic antioxidants activity were stimulated by DI-31 application after four and eight days of mild water shortage, while significantly reduced the lipid-peroxides content. Additionally, our results demonstrated that DI-31 diminishes the nodular senescence and successfully maintains the N homeostasis through a fine tune of biological/assimilative N2-fixation pathways. These findings support the DI-31 potential use as a sustainable alternative for integrative soybean resilience management under drought.

1731: Fertility of Pedicellate Spikelets in Sorghum is Controlled by a Jasmonic Acid Regulatory Module
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Posted to bioRxiv 19 Sep 2019

Fertility of Pedicellate Spikelets in Sorghum is Controlled by a Jasmonic Acid Regulatory Module
82 downloads plant biology

Nicholas P Gladman, Yinping Jiao, Young Koung Lee, Lifang Zhang, Ratan Chopra, Michael Regulski, Gloria Burow, Chad Hayes, Shawn A Christensen, Lavanya Dampanaboina, Junping Chen, John Burke, Doreen Ware, Zhanguo Xin

As in other cereal crops, the panicles of sorghum (Sorghum bicolor (L.) Moench) comprise two types of floral spikelets (grass flowers). Only sessile spikelets (SSs) are capable of producing viable grains, whereas pedicellate spikelets (PSs) cease development after initiation and eventually abort. Consequently, grain number per panicle (GNP) is lower than the total number of flowers produced per panicle. The mechanism underlying this differential fertility is not well understood. To investigate this issue, we isolated a series of EMS-induced multiseeded (msd) mutants that result in full spikelet fertility, effectively doubling GNP. Previously, we showed that MSD1 is a TCP (Teosinte branched/Cycloidea/PCF) transcription factor that regulates jasmonic acid (JA) biosynthesis, and ultimately floral sex organ development. Here, we show that MSD2 encodes a lipoxygenase (LOX) that catalyzes the first committed step of JA biosynthesis. Further, we demonstrate that MSD1 binds to the promoters of MSD2 and other JA pathway genes. Together, these results show that a JA-induced module regulates sorghum panicle development and spikelet fertility. The findings advance our understanding of inflorescence development and could lead to new strategies for increasing GNP and grain yield in sorghum and other cereal crops.

1732: Evaluation of rice wild relatives as a source of traits for adaptation to iron toxicity and enhanced grain quality
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Posted to bioRxiv 16 Sep 2019

Evaluation of rice wild relatives as a source of traits for adaptation to iron toxicity and enhanced grain quality
81 downloads plant biology

Birgit Bierschenk, Melle Tagele, Basharat Ali, MD Ashrafuzzaman, Linbo Wu, Mathias Becker, Michael Frei

Rice wild relatives (RWR) constitute an extended gene pool that can be tapped for the breeding of novel rice varieties adapted to abiotic stresses such as iron (Fe) toxicity. Therefore, we screened 75 Oryza genotypes including 16 domesticated O. sativas , one O. glaberrima , and 58 RWR representing 21 species, for tolerance to Fe toxicity. Plants were grown in a semi-artificial greenhouse setup, in which they were exposed either to control conditions, an Fe shock during the vegetative growth stage (acute treatment), or to a continuous moderately high Fe level (chronic treatment). In both stress treatments, foliar Fe concentrations were characteristic of Fe toxicity, and plants developed foliar stress symptoms, which were more pronounced in the chronic Fe stress especially toward the end of the growing season. Among the genotypes that produced seeds, only the chronic stress treatment significantly reduced yields due to increases in spikelet sterility. Moreover, a moderate but non-significant increase in grain Fe concentrations, and a significant increase in grain Zn concentrations were seen in chronic stress. Both domesticated rice and RWR exhibited substantial genotypic variation in their responses to Fe toxicity. Although no RWR strikingly outperformed domesticated rice in Fe toxic conditions, some genotypes scored highly in individual traits. Two O. meridionalis accessions were best in avoiding foliar symptom formation in acute Fe stress, while an O. rufipogon accession produced the highest grain yields in both chronic and acute Fe stress. In conclusion, this study provides the basis for using interspecific crosses for adapting rice to Fe toxicity.

1733: Whole-genome duplication and host genotype affect rhizosphere microbial communities in Arabidopsis thaliana
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Posted to bioRxiv 30 Oct 2019

Whole-genome duplication and host genotype affect rhizosphere microbial communities in Arabidopsis thaliana
81 downloads plant biology

Julian C Bennett Ponsford, Charley J Hubbard, Joshua G Harrison, Lois Maignien, C Alex Buerkle, Cynthia Weinig

The composition of complex microbial communities found in association with plants is influenced in part by host genotype. Yet, the salient genetic architecture is often unknown. Genome duplication events are common in the evolutionary history of plants, influence many important diverse plant traits, and may affect associated microbial communities. Using genotypes with experimentally induced whole genome duplication (WGD), we tested the effect of WGD on rhizosphere bacterial communities in Arabidopsis thaliana . Specifically, we performed 16s rRNA amplicon sequencing to characterize differences between microbiomes associated with specific host genotypes (Columbia vs. Landsberg) and ploidy levels (diploid vs. tetraploid). We modeled abundances of individual bacterial taxa by utilizing a hierarchical Bayesian framework, based on the Dirichlet and multinomial distributions. We found that host genotype and host ploidy level affected rhizosphere community composition. Further, the microbiome of the tetraploid Columbia genotype differed from that of other host genotypes. We then tested to what extent microbiomes derived from a given host genotype or ploidy level affected plant performance by inoculating sterile seedlings of each genotype with microbial communities harvested from a prior generation, using a full factorial design. We found a negative effect of the tetraploid Columbia microbiome on growth of all four plant genotypes. The findings suggest that while both host genotype and ploidy affect microbial community assembly, bacterial communities found in association with only some host genotypes may affect growth of subsequent plant generations.

1734: Effects of irrigation scheduling and different irrigation methods on onion and water productivity in Tigray, northern Ethiopia
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Posted to bioRxiv 01 Oct 2019

Effects of irrigation scheduling and different irrigation methods on onion and water productivity in Tigray, northern Ethiopia
80 downloads plant biology

Gebremedhin Gebremeskel Haile, T. G. Gebremicael, Mulubrehan Kifle, Teferi Gebremedhin

Efficient irrigation water use can meet its objective if irrigated agriculture is managed properly in regions where water is limited. A two-year (2016-2017) field experiments were conducted in the semi-arid areas of Tigray in northern Ethiopia to evaluate irrigation scheduling with different irrigation methods. The experiments were carried out to identify their contribution for enhancing onion and water productivity in water-stressed irrigation schemes of Korir and Hatset sites. Six factorial treatments comprising of three levels of irrigation methods (furrow, basin and flood) and two levels of irrigation scheduling (fixed interval and farmer’s practices) were evaluated with three replications. The agronomic and irrigation parameters were subjected to separate level-wise comparison followed by the factorial interaction effects. The results showed that the fixed irrigation interval, basin irrigation method and their factorial combinations showed better performances and produced a higher yield and water productivity. On average, 263.85 q/ha and 281 q/ha of onion were obtained under the basin irrigation method and basin irrigation with fixed irrigation interval (T2) at both sites and seasons. For the T2, 6.27 and 6.06 kg/m 3 of water productivity (WP) and 4.39 and 4.24 kg/m 3 of irrigation water productivity (IWP) were obtained at Korir and Hatset sites, respectively showing higher results as compared to other treatment combinations. Moreover, the basin irrigation method produces higher marketable onion bulbs that are essential for onion producers to earn maximum profit from selling and enhance their livelihoods. Treatments comprising basin method and fixed interval showed better onion and water productivity in the water-limited irrigation schemes of Tigray. Hence, focusing on enhanced irrigation scheduling techniques and irrigation methods are important for effective agricultural water management. Farmers, irrigation experts, water resources managers and decision-makers are suggested to use these techniques to save the limited water resources and increase agricultural productivity.

1735: Rapid leaf trait response to growing-season meteorology in Vitis: Implications for leaf physiognomic paleoclimate reconstructions
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Posted to bioRxiv 25 Jul 2019

Rapid leaf trait response to growing-season meteorology in Vitis: Implications for leaf physiognomic paleoclimate reconstructions
80 downloads plant biology

Aly Baumgartner, Michaela Donahoo, Daniel H. Chitwood, Daniel J Peppe

PREMISE OF THE STUDY: The size and shape (physiognomy) of woody, dicotyledonous angiosperm leaves are correlated with climate and these relationships have been used to develop paleoclimate proxies. These proxies assume that leaf morphology plastically responds to meteorological conditions and that leaf traits change isometrically through development. METHODS: We used Digital Leaf Physiognomy (DiLP) to measure leaf characters of multiple Vitis species from the USDA Germplasm Repository in Geneva, NY from the 2012-2013 and 2014-2015 growing seasons. These growing seasons had different temperature and precipitation. KEY RESULTS: We found three primary results: (1) there were predictable significant differences in leaf characters in leaves of different developmental stages along the vine, (2) there were significant differences in leaf characters in leaves of the same developmental stage between the growing seasons, and (3) there were significant differences in leaf characters between growing seasons. CONCLUSIONS: We found that Vitis leaf shape had the strongest relationship with growing season meteorological conditions in taxa growing in their native range. In addition, leaves have variable phenotypic plasticity along the vine. We interpret that the meteorological signal was strongest in those leaves that have completed allometric expansion. This is significant for leaf physiognomic-paleoclimate proxies because these leaves are most likely to be preserved in leaf litter and reflect the type of leaves included in paleoclimate reconstructions. We found that leaf development does have the potential to be a confounding factor, but it is unlikely to exert a significant influence on analysis due to differential preservation potential.

1736: Proteomic and metabolomic profiling underlines the stage- and time-dependent effects of high temperature on grape berry metabolism
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Posted to bioRxiv 18 Oct 2019

Proteomic and metabolomic profiling underlines the stage- and time-dependent effects of high temperature on grape berry metabolism
80 downloads plant biology

David Lecourieux, Christian Kappel, Stephane Claverol, Philippe Pieri, Regina Feil, John E. Lunn, Marc Bonneu, Lijun Wang, Eric Gomes, Serge Delrot, Fatma Lecourieux

Climate change scenarios predict an increase in mean air temperatures and in the frequency, intensity, and length of extreme temperature events in many wine-growing regions worldwide. Because elevated temperature has detrimental effects on the berry growth and composition, it threatens the economic and environmental sustainability of wine production. Using Cabernet Sauvignon fruit-bearing cuttings, we investigated the effects of high temperature (HT) on grapevine berries through a label-free shotgun proteomic analysis coupled to a complementary metabolomic study. Among the 2279 proteins identified, 592 differentially abundant proteins were found in berries exposed to HT. The gene ontology categories Stress, Protein, Secondary metabolism and Cell wall were predominantly altered under HT. High temperatures strongly impaired carbohydrate and energy metabolism, and the effects depended on the stage of development and duration of treatment. Transcript amounts correlated poorly with protein expression levels in HT berries, highlighting the value of proteomic studies in the context of heat stress. Furthermore, this work reveals that HT alters key proteins driving berry development and ripening. Finally, we provide a list of differentially abundant proteins that can be considered as potential markers for developing or selecting grape varieties that are better adapted to warmer climates or extreme heat waves.

1737: Varietal differences in physiological and biochemical responses to salinity stress in six finger millet plants
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Posted to bioRxiv 02 Oct 2019

Varietal differences in physiological and biochemical responses to salinity stress in six finger millet plants
79 downloads plant biology

Asunta Mukami, Alex Ngetich, Easter Syombua, Richard Oduor, Wilton Mwema Mbinda

Finger millet is one of the most important cereals that are often grown in semiarid and arid regions of East Africa. However, salinity is known to be a major impediment for the crop growth and production. The goal of this study was to understand the mechanisms of physiological and biochemical responses to salinity stress of six Kenyan finger millet varieties (GBK043137, GBK043128, GBK043124, GBK043122, GBK043094, and GBK043050) grown across different agroecological zones under NaCl-induced salinity stress. Seeds were germinated on the sterile soil and treated using various concentrations of NaCl (100, 200 and 300 mM) for two weeks. Again, the early seedling stage of germinated plants was irrigated with the same salt concentrations for 60 days. Results indicated depression in germination percentage, shoot and root growth rate, leaf relative water content, total chlorophyll content contents, leaf K ion concentration, and leaf K/Na ratios in all varieties studied with increased salt levels. On the contrary, it was observed that proline and malonaldehyde (MDA) contents reduced sugar content and leaf total proteins. At the same time, the leaf Na ion and Cl ion amounts of all plants increased substantially with rising stress levels. Clustering analysis revealed that GBK043094 and GBK043137 were placed together and identified as salt tolerant varieties based on their performance under salt stress. Overall, our findings indicated a significant varietal variability for most of the parameters analysed. These superior varieties identified could be potentially used as promising genetic resources in future breeding programmes development directed towards salt-tolerant finger millet hybrids. However, further analysis at genomic and molecular level need to be undertaken in order to better understand specific mechanisms of the factors that promote salinity tolerance in finger millet.

1738: ForageGrassBase: Molecular resource for the forage grass Festuca pratensis Huds.
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Posted to bioRxiv 19 Jun 2019

ForageGrassBase: Molecular resource for the forage grass Festuca pratensis Huds.
79 downloads plant biology

Jeevan Karloss Antony Samy, Odd Arne Rognli, Mallikarjuna Rao Kovi

Background: Meadow fescue (Festuca pratensis Huds.) is one of the most important forage grasses in temperate regions. F. pratensis is a diploid (2n =14) outbreeding species that belongs to the genus Festuca. Together with Lolium, they are the most important genera of forage grasses in temperate regions. F. pratensis has good winter survival, with high quality dry matter yields and persistency, and is suitable both for frequent-cutting conservation regimes and for grazing. It is a significant component of species-rich permanent pastures in the temperate regions, ensuring high forage yield under harsh climatic conditions where other productive forage grass species are unable to grow. However, genomic resources for F. Pratensis is not available so far. Results: The draft genome sequences of two F. pratensis genotypes HF7/2 and B14/16 are reported in this study. Here, using the draft genome, functional annotation datasets of two F. pratensis cultivars, we have constructed the F. pratensis genome database http://foragegrass.org/, the first open-access platform to provide comprehensive genomic resources related to this forage grass species. The current version of this database provides the most up-to-date draft genome sequence along with structural and functional annotations for genes using Genome Browser (GBrowse). In addition, we have integrated comparative genomic tracks for F. pratensis genomes by mapping F.pratensis genome to the barley, rice, Brachypodium and maize genomes. We have integrated homologus search tool BLAST also for the users to analyze their data. Combined, GBrowse, BLAST and downloadble data gives an user friendly access to F. pratensis genomic resouces. All data in the database were manually curated. Conclusion: To our knowledge, ForageGrassBase is the first genome database dedicated to forage grasses. It provides valuable resources for a range of research fields related to F. pratensis and other forage crop species, as well as for plant research communities in general. The genome database can be accessed at http://foragegrass.org. In the near future, we will expand the ForageGrassBase by adding genomic tools for other forage grass species, as soon as their genomes become available.

1739: Evidence for pre-climacteric activation of AOX transcription during cold-induced conditioning to ripen in European pear (Pyrus communis L.)
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Posted to bioRxiv 03 Sep 2019

Evidence for pre-climacteric activation of AOX transcription during cold-induced conditioning to ripen in European pear (Pyrus communis L.)
79 downloads plant biology

Christopher Hendrikckson, Seanna Hewitt, Mark E Swanson, Todd Einhorn, Amit Dhingra

European pears (Pyrus communis L.) require a range of cold-temperature exposure to induce ethylene biosynthesis and fruit ripening. Physiological and hormonal responses to cold temperature storage in pear have been well characterized, but the molecular underpinnings of these phenomena remain unclear. An established low-temperature conditioning model was used to induce ripening of DAnjou and Bartlett pear cultivars and quantify the expression of key genes representing ripening-related metabolic pathways in comparison to non-conditioned fruit. Physiological indicators of pear ripening were recorded, and fruit peel tissue sampled in parallel, during the cold-conditioning and ripening time-course experiment to correlate gene expression to ontogeny. Two complementary approaches, Nonparametric Multi-Dimensional Scaling and efficiency-corrected 2-(dd-Ct), were used to identify genes exhibiting the most variability in expression. Interestingly, the enhanced alternative oxidase (AOX) transcript abundance at the pre-climacteric stage in Bartlett and DAnjou at the peak of the conditioning treatments suggests that AOX may play a key and a novel role in the achievement of ripening competency. There were indications that cold-sensing and signaling elements from ABA and auxin pathways modulate the S1-S2 ethylene transition in European pears, and that the S1-S2 ethylene biosynthesis transition is more pronounced in Bartlett as compared to DAnjou pear. This information has implications in preventing post-harvest losses of this important crop.

1740: KAKU4-mediated deformation of the vegetative nucleus controls its precedent migration over sperm cells in pollen tubes
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Posted to bioRxiv 19 Sep 2019

KAKU4-mediated deformation of the vegetative nucleus controls its precedent migration over sperm cells in pollen tubes
79 downloads plant biology

Chieko Goto, Kentaro Tamura, Satsuki Nishimaki, Naoki Yanagisawa, Kumi Matsuura-Tokita, Tetsuya Higashiyama, Daisuke Maruyama, Ikuko Hara-Nishimura

A putative nuclear lamina protein, KAKU4, modulates nuclear morphology in Arabidopsis thaliana seedlings but its physiological significance is unknown. KAKU4 was strongly expressed in mature pollen grains, each of which has a vegetative cell and two sperm cells. KAKU4 protein was highly abundant on the envelopes of vegetative nuclei (VNs) and less abundant on the envelopes of sperm cell nuclei (SCNs) in pollen grains and elongating pollen tubes. VN is irregularly shaped in wild-type pollen. However, KAKU4 deficiency caused it to become more spherical. These results suggest that the dense accumulation of KAKU4 is responsible for the irregular shape of the VNs. After a pollen grain germinates, the VN and SCNs migrate to the tip of the pollen tube. In the wild type, the VN preceded the SCNs in 91-93% of the pollen tubes, whereas in kaku4 mutants, the VN trailed the SCNs in 39-58% of the pollen tubes. kaku4 pollen was less competitive than wild-type pollen after pollination, although it had an ability to fertilize. Taken together, our results suggest that controlling the nuclear shape in vegetative cells of pollen grains by KAKU4 ensures the orderly migration of the VN and sperm cells in pollen tubes.

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