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in category plant biology

2,483 results found. For more information, click each entry to expand.

1721: The power of model-to-crop translation illustrated by reducing seed loss from pod shatter in oilseed rape
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Posted to bioRxiv 10 Apr 2019

The power of model-to-crop translation illustrated by reducing seed loss from pod shatter in oilseed rape
234 downloads plant biology

Pauline Stephenson, Nicola Stacey, Marie Brüser, Nick Pullen, Muhammad Ilyas, Carmel O’Neill, Rachel Wells, Lars Østergaard

In the 1980s, plant scientists descended on a small weed Arabidopsis thaliana (thale cress) and developed it into a powerful model system to study plant biology. The massive advances in genetics and genomics since then has allowed us to obtain incredibly detailed knowledge on specific biological processes of Arabidopsis growth and development, its genome sequence and the function of many of the individual genes. This wealth of information provides immense potential for translation into crops to improve their performance and address issues of global importance such as food security. Here we describe how fundamental insight into the genetic mechanism by which seed dispersal occurs in members of the Brassicaceae family can be exploited to reduce seed loss in oilseed rape (Brassica napus). We demonstrate that by exploiting data on gene function in model species, it is possible to adjust the pod-opening process in oilseed rape thereby significantly increasing yield. Specifically, we identified mutations in multiple paralogues of the INDEHISCENT and GA4 genes in B. napus and have overcome genetic redundancy by combining mutant alleles. Finally, we present novel software for the analysis of pod shatter data that is applicable to any crop for which seed dispersal is a serious problem. These findings highlight the tremendous potential of fundamental research in guiding strategies for crop improvement.

1722: MADS-box factor AGL16 negatively regulates drought resistance via stomatal density and stomatal movement
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Posted to bioRxiv 02 Aug 2019

MADS-box factor AGL16 negatively regulates drought resistance via stomatal density and stomatal movement
234 downloads plant biology

Ping-Xia Zhao, Zi-Qing Miao, Jing Zhang, Qian-Qian Liu, Cheng-Bin Xiang

Drought is one of the most severe environmental factors limiting plant growth and productivity. Plants respond to drought by closing stomata to reduce water loss. The molecular mechanisms underlying plant drought resistance are very complex and yet to be fully understood. While much research attention has been focused on the positive regulation of stomatal closure, less is known about its negative regulation, equally important in this reversible process. Here we show that the MADS-box transcriptional factor AGL16 acts as a negative regulator in drought resistance by regulating both stomatal density and movement. Loss-of-function mutant agl16 was more resistant to drought stress with higher relative water content, which was attributed to a reduced leaf stomatal density and more sensitive stomatal closure due to a higher leaf ABA level compared with wild type, while AGL16 overexpression lines displayed the opposite phenotypes. AGL16 is preferentially expressed in guard cells and down regulated in response to drought stress. The expression of CYP707A3 and AAO3 in ABA metabolism and SDD1 in stomatal development was altered by AGL16 as shown in agl16 and overexpression lines. Chromatin immunoprecipitation, transient transactivation, and yeast-one-hybrid assays demonstrated that AGL16 bound the CArG motif in the promoter of the CYP707A3, AAO3, and SDD1 to regulate their transcription, and therefore alter leaf stomatal density and ABA level. Taken together, AGL16 acts as a negative regulator of drought resistance by modulating leaf stomatal density and ABA accumulation.

1723: Salinity shock in Jatropha curcas leaves is more pronounced during recovery than during stress time
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Posted to bioRxiv 26 Jul 2018

Salinity shock in Jatropha curcas leaves is more pronounced during recovery than during stress time
234 downloads plant biology

Leonardo Silva-Santos, Natália Corte-Real, Jaqueline Dias-Pereira, Regina C.B.Q. Figueiredo, Lauricio Endres, Marcelo F. Pompelli

To verify the possible morphological and ultrastructural differences in the Jatropha curcas leaves, in response to high-intensity salt stress, three genotypes were evaluated (CNPAE183, JCAL171 and CNPAE218). In all the genotypes, 750mM NaCl, added to the nutrient solution, was applied to test its salt tolerance. For the analysis, the leaves were collected at three time points: (i) before stress (time 0 hour); (ii) during stress time (time 50 hours); and (iii) in the recovery period (time 914 hours) when the stressed plants recovered and demonstrated measurements of net photosynthetic with values similar to those demonstrated by the control plants. We showed that regardless of the genotype, saline shock caused an increase in the thickness of the mesophyll, and after the removal of NaCl, the thicker mesophyll remained in the JCAL171 and CNPAE218 genotypes, while the values observed in the CNPAE183 genotype were similar to those before stress. Scanning electron microscopy indicated that the stomata of CNPAE183 are smaller and have a stomatal index higher than the values demonstrated in JCAL171 and CNPAE218. Therefore, among the genotypes analysed, CNPAE183 demonstrates that it could be considered a promising genotype for future studies of genetic improvement that seek elite genotypes tolerant to salinity.

1724: Endosidin20 targets cellulose synthase catalytic domain to inhibit cellulose biosynthesis
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Posted to bioRxiv 17 Feb 2020

Endosidin20 targets cellulose synthase catalytic domain to inhibit cellulose biosynthesis
234 downloads plant biology

Lei Huang, Xiaohui Li, Weiwei Zhang, Nolan Ung, Nana Liu, Xianglin Yin, Yong Li, Robert E Mcewan, Brian P. Dilkes, Mingji Dai, Glenn R. Hicks, Natasha V Raikhel, Christopher J. Staiger, Chunhua Zhang

Cellulose is synthesized by rosette structured cellulose synthase (CESA) complexes (CSCs), each of which is composed of multiple units of CESAs in three different isoforms. CSCs rely on vesicle trafficking for delivery to the plasma membrane where they catalyze cellulose synthesis. Although the rosette structured CSCs were observed decades ago, it remains unclear what amino acids in plant CESA that directly participate in cellulose catalytic synthesis. It is not clear how the catalytic activity of CSCs influences their efficient transport at the subcellular level. We report characterization of the small molecule Endosidin20 (ES20) and present evidence that it represents a new CESA inhibitor. We show chemical genetic analyses, biochemical assays, structural modeling, and molecular docking to support our conclusion that ES20 targets the catalytic site of Arabidopsis CESA6. Chemical genetic analysis reveals important amino acids that potentially form the catalytic site of plant CESA6. Using high spatiotemporal resolution live-cell imaging, we found that inhibition of CSC catalytic activity by inhibitor treatment, or by creating missense mutation at amino acids in the predicted catalytic site, causes reduced efficiency in CSC transport to the plasma membrane. We show that the catalytic activity of plant CSCs is integrated with subcellular trafficking dynamics.

1725: Variation in maize chlorophyll biosynthesis alters plant architecture
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Posted to bioRxiv 24 Jan 2020

Variation in maize chlorophyll biosynthesis alters plant architecture
234 downloads plant biology

Rajdeep S. Khangura, Gurmukh S. Johal, Brian P. Dilkes

Chlorophyll is a tetrapyrrole metabolite essential for photosynthesis in plants. The oil yellow1 (oy1) gene of maize encodes subunit I of Magnesium chelatase, the enzyme catalyzing the first committed step of chlorophyll biosynthesis. A range of chlorophyll contents and net CO2 assimilation rates can be achieved in maize by combining a semi-dominant mutant allele, Oy1-N1989, and cis-regulatory alleles encoded by the Mo17 inbred called very oil yellow1 (vey1). We previously demonstrated that these allelic interactions can delay reproductive maturity. In this study, we demonstrate that multiple gross morphological traits respond to a reduction in chlorophyll. We found that stalk width, number of lateral branches (tillers), and branching of the inflorescence decline with a decrease in chlorophyll level. Chlorophyll variation suppressed tillering in multiple maize mutants including teosinte branched1, grassy tiller1, and Tillering1 as well as the tiller number1 QTL responsible for tillering in many sweet corn varieties. In contrast to these traits, plant height showed a non-linear response to chlorophyll levels. Weak suppression of Oy1-N1989 by vey1B73 resulted in a significant increase in mutant plant height. This was true in multiple mapping populations, isogenic inbreds, and hybrid backgrounds. Enhancement of the Oy1-N1989 mutants by the vey1Mo17 allele reduced chlorophyll contents and plant height in mapping populations and isogenic inbred background. We demonstrate that the effects of reduced chlorophyll content on plant growth and development are complex and that the genetic relationship depends on the trait. We propose that growth control for branching and architecture are downstream of energy balance sensing.

1726: Dmc1 is a candidate for temperature tolerance during wheat meiosis
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Posted to bioRxiv 16 Sep 2019

Dmc1 is a candidate for temperature tolerance during wheat meiosis
234 downloads plant biology

Tracie Draeger, Azahara Martin, Abdul Kader Alabdullah, Ali Pendle, María-Dolores Rey, Peter Shaw, Graham Moore

We have assessed the effects of high and low temperatures on meiotic chromosome synapsis and crossover formation in the hexaploid wheat (Triticum aestivum L.) variety 'Chinese Spring'. At low temperatures, asynapsis and chromosome univalence have been observed before in Chinese Spring lines lacking the long arm of chromosome 5D (5DL), which led to the proposal that 5DL carries a gene (Ltp1) that stabilises wheat chromosome pairing at low temperatures. In the current study, Chinese Spring wild type and 5DL interstitial deletion mutant plants were exposed to low (13°C) or high (30°C) temperatures in controlled environment rooms during a period from premeiotic interphase to early meiosis I. A 5DL deletion mutant was identified whose meiotic chromosomes exhibit extremely high levels of asynapsis and chromosome univalence at metaphase I after seven days at 13°C. This suggests that the mutant, which we name ttmei1 (temperature tolerance in meiosis 1) has a deletion of a gene that, like Ltp1, normally stabilises chromosome pairing at low temperatures. Immunolocalisation of the meiotic proteins ASY1 and ZYP1 on ttmei1 mutants showed that low temperature results in a failure to complete synapsis at pachytene. After 24 hours at 30°C, ttmei1 mutants exhibited a reduced number of crossovers and increased univalence, but to a lesser extent than at 13°C. KASP genotyping revealed that ttmei1 has a 4 Mb deletion in 5DL. Of 41 genes within this deletion region, the strongest candidate for the stabilisation of chromosome pairing at low (and possibly high) temperatures is the meiotic recombination gene Dmc1.

1727: Arabidopsis PAD4 lipase-like domain is a minimal functional unit in resistance to green peach aphid
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Posted to bioRxiv 14 Sep 2019

Arabidopsis PAD4 lipase-like domain is a minimal functional unit in resistance to green peach aphid
234 downloads plant biology

Joram A. Dongus, Deepak D. Bhandari, Monika Patel, Lani Archer, Lucas Dijkgraaf, Laurent Deslandes, Jyoti Shah, Jane E. Parker

Plants have evolved mechanisms to attract beneficial microbes and insects while protecting themselves against pathogenic microbes and pests. In Arabidopsis, the immune regulator PAD4 functions with its cognate partner EDS1 to limit pathogen growth. PAD4, independently of EDS1, reduces infestation by Green Peach Aphid (GPA). How PAD4 regulates these defense outputs is unclear. By expressing the N-terminal PAD4-lipase-like domain (LLD) without its C-terminal "EDS1-PAD4" (EP) domain, we interrogated PAD4 functions in plant defense. Here we show that transgenic expression of PAD4LLD in Arabidopsis is sufficient for limiting GPA infestation, but not for conferring basal and effector-triggered pathogen immunity. This suggests that the C-terminal PAD4-EP domain is necessary for EDS1-dependent immune functions. Moreover, PAD4LLD is not sufficient to interact with EDS1, indicating the PAD4-EP domain is required for heterodimerisation. These data provide molecular evidence that PAD4 has domain specific functions.

1728: Chemical identification of 18-hydroxycarlactonoic acid as an LjMAX1 product and conversion of 18-hydroxylcarlactonoates to canonical and non-canonical strigolactones in Lotus japonicus
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Posted to bioRxiv 11 Nov 2019

Chemical identification of 18-hydroxycarlactonoic acid as an LjMAX1 product and conversion of 18-hydroxylcarlactonoates to canonical and non-canonical strigolactones in Lotus japonicus
234 downloads plant biology

Narumi Mori, Aika Sado, Xiaonan Xie, Kaori Yoneyama, Kei Asami, Yoshiya Seto, Takahito Nomura, Shinjiro Yamaguchi, Koichi Yoneyama, Kohki Akiyama

Strigolactones (SLs) are a group of plant apocarotenoids that act as rhizosphere signaling molecules for both arbuscular mycorrhizal fungi and root parasitic plants. They also regulate plant architecture as phytohormones. The model legume Lotus japonicus produces canonical 5-deoxystrigol (5DS) and non-canonical lotuslactone (LL). The biosynthesis pathways of the two SLs remain elusive. In this study, we characterized the L. japonicus MAX1 homolog, LjMAX1 , found in the Lotus japonicus genome assembly build 2.5. The L. japonicus max1 LORE1 insertion mutant was deficient in 5DS and LL production. A recombinant LjMAX1 protein expressed in yeast microsomes converted carlactone (CL) to 18-hydroxycarlactonoic acid (18-HO-CLA) via carlactonoic acid (CLA). Identity of 18-HO-CLA was confirmed by comparison of the methyl ester derivative of the MAX1 product with the chemically synthesized methyl 18-hydroycarlactonoate (18-HO-MeCLA) using LC-MS/MS. (11 R )-CL was detected as an endogenous compound in the root of L. japonicus . 13C-labeled CL, CLA, and 18-HO-MeCLA were converted to [13C]-5DS and LL in plant feeding experiments using L. japonicus WT. These results showed that LjMAX1 is the crucial enzyme in the biosynthesis of Lotus SLs and that 18-hydroxylated carlactonoates are precursors for SL biosynthesis in L. japonicus .

1729: Synergetic effect of non-complementary 5′ AT-rich sequences on the development of a multiplex TaqMan real-time PCR for specific and robust detection of Clavibacter michiganensis and C. michiganensis subsp. nebraskensis
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Posted to bioRxiv 11 Mar 2019

Synergetic effect of non-complementary 5′ AT-rich sequences on the development of a multiplex TaqMan real-time PCR for specific and robust detection of Clavibacter michiganensis and C. michiganensis subsp. nebraskensis
233 downloads plant biology

Adriana Larrea-Sarmiento, Anne M. Alvarez, James P. Stack, Mohammad Arif

Clavibacter is an agriculturally important genus comprising a single species, Clavibacter michiganensis, and multiple subspecies, including, C. michiganensis subsp. nebraskensis which causes Goss's wilt/blight of corn and accounts for high yield losses - listed among the five most significant diseases of corn in the United States of America. Our research objective was to develop a robust and rapid multiplex TaqMan real-time PCR (qPCR) to detect C. michiganensis in general and C. michiganensis subsp. nebraskensis with enhanced reliability and accuracy by adding non-complementary AT sequences to the 5′ end of the forward and reverse primers. Comparative genomic analyses were performed to identify unique and conserved gene regions for primer and probe design. The unique genomic regions, ABC transporter ATP-binding protein CDS/ABC-transporter permease and MFS transporter were determined for specific detection of C. michiganensis and C. m. subsp. nebraskensis, respectively. The AT-rich sequences at the 5′ position of the primers enhanced the reaction efficiency and sensitivity of rapid qPCR cycling; the reliability, accuracy and high efficiency of the developed assay was confirmed after testing with 59 strains from inclusivity and exclusivity panels; no false positives or false negatives were detected. The assays were also validated through naturally and artificially infected corn plant samples; all samples were detected for C. michiganensis and C. m. subsp. nebraskensis with 100% accuracy. The assay with 5′ AT-rich sequences detected up to 10- and 100-fg of C. michiganensis and C. michiganensis subsp. nebraskensis genome targets, respectively. No adverse effect was observed when sensitivity assays were spiked with host genomic DNA. Addition of 5′ AT rich sequences enhanced the qPCR reaction efficiency from 0.82 (M = -3.83) and 0.91 (M = -3.54) to 1.04 (with optimum slope value; M = -3.23) for both C. michiganensis and C. michiganensis subsp. nebraskensis, respectively; a increase of 10-fold sensitivity was also obtained with C. michiganensis primer set. The methodology proposed here can be used to optimize the reaction efficiency and to harmonize the diagnostic protocols which have prodigious applications in routine diagnostics, biosecurity and microbial forensics.

1730: Barley ROP-INTERACTIVE PARTNER-a organizes into RAC1- and MICROTUBULE-ASSOCIATED ROP-GTPASE ACTIVATING PROTEIN 1-dependent membrane domains
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Posted to bioRxiv 09 Jul 2019

Barley ROP-INTERACTIVE PARTNER-a organizes into RAC1- and MICROTUBULE-ASSOCIATED ROP-GTPASE ACTIVATING PROTEIN 1-dependent membrane domains
233 downloads plant biology

Caroline Hoefle, Christopher McCollum, Ralph Hückelhoven

Small ROP (also called RAC) GTPases are key factors in polar cell development and in interaction with the environment. ROP-Interactive Partner (RIP) proteins are predicted scaffold or ROP-effector proteins, which function downstream of activated GTP-loaded ROP proteins in establishing membrane heterogeneity and cellular organization. Grass ROP proteins function in cell polarity, resistance and susceptibility to fungal pathogens but grass RIP proteins are little understood. We found that the barley (Hordeum vulgare L.) RIPa protein can interact with barley ROPs in yeast. Fluorescent-tagged RIPa, when co-expressed with the constitutively activated ROP protein CA RAC1, accumulates at the cell periphery or plasma membrane. Additionally, RIPa, locates into membrane domains, which are laterally restricted by microtubules, when co-expressed with RAC1 and MICROTUBULE-ASSOCIATED ROP-GTPASE ACTIVATING PROTEIN 1. Both structural integrity of MICROTUBULE-ASSOCIATED ROP-GTPASE ACTIVATING PROTEIN 1 and microtubule stability are key to maintenance of RIPa-labeled membrane domains. In this context, RIPa also accumulates at the interface of barley and invading hyphae of the powdery mildew fungus Blumeria graminis f.sp. hordei. Data suggest that barley RIPa interacts with barley ROPs and specifies RAC1 activity-associated membrane domains with potential signaling capacity. Lateral diffusion of this RAC1 signaling capacity is restricted the resulting membrane heterogeneity requires intact microtubules and MICROTUBULE-ASSOCIATED ROP-GTPASE ACTIVATING PROTEIN 1. Focal accumulation of RIPa at sites of fungal attack may indicate locally restricted ROP activity at sites of fungal invasion.

1731: MuSCA: a multi-scale model to explore carbon allocation in plants
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Posted to bioRxiv 16 Jul 2018

MuSCA: a multi-scale model to explore carbon allocation in plants
233 downloads plant biology

F. Reyes, B. Pallas, C. Pradal, F. Vaggi, D. Zanotelli, M. Tagliavini, D. Gianelle, E. Costes

Background and aims: Carbon allocation in plants is usually represented at a specific spatial scale, peculiar to each model. This makes the results obtained by different models, and the impact of their scale of representation, difficult to compare. In this work we developed a Multi Scale Carbon Allocation model (MuSCA) that can be applied at different, user-defined, topological scales of a plant, and used to assess the impact of each spatial scale on simulated results and computation time. Methods: Model multi-scale consistency and behavior were tested by applications on three realistic apple tree structures. Carbon allocation was computed at five spatial scales, spanning from the metamer (the finest scale, used as a reference) up to 1st order branches, and for different values of a sap friction coefficient. Fruit dry mass increments were compared across spatial scales and with field data. Key Results: The model showed physiological coherence in representing competition for carbon assimilates. Results from intermediate values of the friction parameter best fitted the field data. For these, fruit growth simulated at the metamer scale (considered as a reference) differed from about 1% at growth unit scale up to 35% at first order branch scale. Generally, the coarser the spatial scale the more fruit growth diverged from the reference and the lower the obtained within-tree fruit growth variability. Coherence in the carbon allocated across scales was also differently impacted, depending on the tree structure considered. Decreasing the topological resolution reduced computation time up to four orders of magnitude. Conclusions: MuSCA revealed that the topological scale has a major influence on the simulation of carbon allocation, suggesting that this factor should be carefully evaluated when using different carbon allocation models or comparing their results. Trades-off between computation time and prediction accuracy can be evaluated by changing topological scales.

1732: CHLOROPLAST UNUSUAL POSITIONING 1 is a new type of actin nucleation factor in plants
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Posted to bioRxiv 15 Jan 2020

CHLOROPLAST UNUSUAL POSITIONING 1 is a new type of actin nucleation factor in plants
233 downloads plant biology

Sam-Geun Kong, Atsushi Shimada, Saku T. Kijima, Keiko Hirose, Kaoru Katoh, Jeongsu Ahn, Takeshi Higa, Akira Takano, Yuki Nakamura, Noriyuki Suetsugu, Daisuke Kohda, Taro Q. P. Uyeda, Masamitsu Wada

Plants have evolved unique responses to fluctuating light conditions in their environment. One such response, chloroplast photorelocation movement, optimizes photosynthesis under weak light and prevents photodamage under strong light. CHLOROPLAST UNUSUAL POSITIONING 1 (CHUP1) plays a pivotal role in the light-responsive chloroplast movements, which are driven by dynamic reorganization of chloroplast actin (cp-actin) filaments. In this study, we demonstrated that fluorescently tagged CHUP1 colocalized and was coordinately reorganized with cp-actin filaments during chloroplast movement in Arabidopsis thaliana. The resulting asymmetric distribution of CHUP1 was reversibly regulated by the blue light receptor phototropin. X-ray crystallography indicated that the CHUP1 C-terminal domain shares structural similarity with the formin homology 2 (FH2) domain, although there is no sequence similarity between the two domains. The CHUP1 C-terminal domain stimulated actin polymerization in the presence of profilin. We conclude that CHUP1 is a novel, plant-specific actin nucleator that functions in cp-actin-based chloroplast movement.

1733: The ALBA RNA-binding proteins function redundantly to promote growth and flowering in Arabidopsis.
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Posted to bioRxiv 05 Sep 2019

The ALBA RNA-binding proteins function redundantly to promote growth and flowering in Arabidopsis.
233 downloads plant biology

Naiqi Wang, Meachery Jalajakumari, Thomas Miller, Mohsen Asadi, Anthony A Millar

RNA-binding proteins (RBPs) are critical regulators of gene expression, but have been poorly studied relative to other classes of gene regulators. Recently, mRNA-interactome capture identified many Arabidopsis RBPs of unknown function, including a family of ALBA domain containing proteins. Arabidopsis has three short-form ALBA homologues (ALBA1-3) and three long-form ALBA homologues (ALBA4-6), both of which are conserved throughout the plant kingdom. Despite this ancient origin, ALBA-GUS translational fusions of ALBA1, ALBA2, ALBA4, and ALBA5 had indistinguishable expression patterns, all being preferentially expressed in young, rapidly dividing tissues. Likewise, all four ALBA proteins had indistinguishable ALBA-GFP subcellular localizations in roots, all being preferentially located to the cytoplasm, consistent with being mRNA-binding. Genetic analysis demonstrated redundancy within the long-form ALBA family members; in contrast to single alba mutants that all appeared wild-type, a triple alba456 mutant had slower rosette growth and a strong delay in flowering-time. RNA-sequencing found most differentially expressed genes in alba456 were related to metabolism, not development. Additionally, changes to the alba456 transcriptome were subtle, suggesting ALBA4-6 participates in a process that does not strongly affect transcriptome composition. Together, our findings demonstrate that ALBA protein function is highly redundant, and is essential for proper growth and flowering in Arabidopsis.

1734: Sensing Plant Physiology and Environmental Stress by Automatically Tracking Fj and Fi Features in PSII Chlorophyll Fluorescence Induction
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Posted to bioRxiv 05 Jul 2018

Sensing Plant Physiology and Environmental Stress by Automatically Tracking Fj and Fi Features in PSII Chlorophyll Fluorescence Induction
233 downloads plant biology

Qian Xia, Jinglu Tan, Shengyang Cheng, Yongnian Jiang, Ya Guo

Following a step excitation, chlorophyll fluorescence (ChlF) from photosystem II of a dark-adapted plant leaf exhibits the well-known OJIP pattern. The OJIP induction has been widely applied in plant science, agriculture engineering, and environmental engineering. While the J and I phases are related to transitions of photochemical reaction redox states, characteristic fluorescence intensities for the two phases (Fj and Fi) are often treated as fixed time points in routine measurement and thus do not account for variations in plant and experimental conditions, which (1) neglects the time differences, potentially useful information for characterizing plant status and environmental factors, and (2) leads to errors in measured Fj and Fi values. In this work, a method for consistent measurement of Fj and Fi was developed through polynomial fitting and curvature analysis. The method measures the curvatures in the OJIP curve and automatically tracks the characteristic transition points under variable sample and experimental conditions. Experiments were carried out to demonstrate the concept and classification capabilities of the developed method. This research established a new framework to analyze ChlF and enhanced the applications of ChlF.

1735: Allometric scaling impacts plasticity in biomass allocation, morphology and anatomical traits due to above and belowground resource limitation in cultivated sunflower (Helianthus annuus L.)
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Posted to bioRxiv 21 Dec 2018

Allometric scaling impacts plasticity in biomass allocation, morphology and anatomical traits due to above and belowground resource limitation in cultivated sunflower (Helianthus annuus L.)
232 downloads plant biology

Yan Wang, Lisa A. Donovan, Andries A. Temme

The extent of plant trait adjustment in response to a changed environment is generally considered as the plant’s phenotypic plasticity ([Nicotra et al ., 2010][1]; [Valladares et al ., 2007][2]). According to theory (Gedroc et al ., 1996; Shippley & Mezianne 2002; [Poorter et al ., 2012][3]; [

1736: Spatial photosynthesis modelling sets guidelines to constructing a viable single-cell cytoplasm-to-stroma C4 cycle
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Posted to bioRxiv 02 Mar 2018

Spatial photosynthesis modelling sets guidelines to constructing a viable single-cell cytoplasm-to-stroma C4 cycle
232 downloads plant biology

Ivan Jurić, Julian M. Hibberd, Mike Blatt, Nigel J Burroughs

It has been proposed that introducing C4 photosynthesis into C3 crops would increase yield. The simplest scheme involves concentrating carbon originating from the cytosol in the chloroplast stroma of mesophyll cells without altering leaf or cell anatomy. Photosynthetic efficiency would then strongly depend on the chloroplast envelope permeability to CO2. We examine the performance of this C4 cycle with a spatial model of carbon assimilation in C3 mesophyll cell geometry, conducting a thorough exploration of parameter space relevant to C4 photosynthesis. For envelope permeabilities below 300 μm/s C4 photosynthesis has a higher quantum efficiency than C3. However, even when envelope permeability is above this threshold, the C4 pathway can provide a substantial boost to carbon assimilation with only a moderate decrease in efficiency. Depending on the available light-harvesting capacity of plastids, C4 photosynthesis could boost carbon assimilation anywhere from 20% to 100%. Gains are even more prominent under CO2 deprivation, and can be achieved in conjunction with lower investment in plastids if chloroplast surface coverage is also altered. A C4 pathway operating within individual mesophyll cells of C3 plants could hence lead to higher growth rates and better drought resistance in dry, high-sunlight climates.

1737: Litterbox - A gnotobiotic zeolite-clay system to investigate Arabidopsis-microbe interactions
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Posted to bioRxiv 28 Jan 2020

Litterbox - A gnotobiotic zeolite-clay system to investigate Arabidopsis-microbe interactions
232 downloads plant biology

Moritz Miebach, Rudolf O. Schlechter, John Clemens, Paula E. Jameson, Daniela M. Remus

Plants are colonised by millions of microorganisms representing thousands of species with varying effects on plant growth and health. The microbial communities found on plants are compositionally consistent and their overall positive effect on the plant is well known. However, the effects of individual microbiota members on plant hosts and vice versa, as well as the underlying mechanisms remain largely unknown. Here, we describe "Litterbox", a highly controlled system to investigate plant-microbe interactions. Plants were grown gnotobiotically on zeolite-clay, an excellent soil replacement that retains enough moisture to avoid subsequent watering. Plants grown on zeolite phenotypically resemble plants grown under environmental conditions. Further, bacterial densities on leaves in the Litterbox system resembled those in temperate environments. A PDMS sheet was used to cover the zeolite, thereby significantly lowering the bacterial load in the zeolite and rhizosphere. This reduced the likelihood of potential systemic responses in leaves induced by microbial rhizosphere colonisation. We present results of example experiments studying the transcriptional responses of leaves to defined microbiota members and the spatial distribution of bacteria on leaves. We anticipate that this versatile and affordable plant growth system will promote microbiota research and help in elucidating plant-microbe interactions and their underlying mechanisms.

1738: High resolution mapping of a Hordeum bulbosum-derived powdery mildew resistance locus in barley using distinct homologous introgression lines
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Posted to bioRxiv 06 Dec 2019

High resolution mapping of a Hordeum bulbosum-derived powdery mildew resistance locus in barley using distinct homologous introgression lines
231 downloads plant biology

Parastoo Hoseinzadeh, Brigitte Ruge-Wehling, Patrick Schweizer, Nils Stein, Hélène Pidon

Powdery mildew caused by Blumeria graminis f.sp. hordei ( Bgh ) is one of the main foliar diseases in barley ( Hordeum vulgare L.; Hv ). Naturally occurring resistance genes used in barley breeding are a cost effective and environmentally sustainable strategy to minimize the impact of pathogens, however, the primary gene pool of H. vulgare contains limited diversity owing to recent domestication bottlenecks. To ensure durable resistance against this pathogen, more genes are required that could be unraveled by investigation of secondary barley gene-pool. A large set of Hordeum bulbosum ( Hb ) introgression lines (ILs) harboring a diverse set of desirable resistance traits have been developed and are being routinely used as source of novel diversity in gene mapping studies. Nevertheless, this strategy is often compromised by a lack of recombination between the introgressed fragment and the orthologous chromosome of the barley genome. In this study, we fine-mapped a Hb gene conferring resistance to barley powdery mildew. The initial genotyping of two Hb ILs mapping populations with differently sized 2HS introgressions revealed severely reduced interspecific recombination in the region of the introgressed segment, preventing precise localization of the gene. To overcome this difficulty, we developed an alternative strategy, exploiting intraspecific recombination by crossing two Hv / Hb ILs with collinear Hb introgressions, one of which carries a powdery mildew resistance gene, while the other doesn't. The intraspecific recombination rate in the Hb -introgressed fragment of 2HS was approximately 20 times higher than it was in the initial simple ILs mapping populations. Using high-throughput genotyping-by-sequencing (GBS), we allocated the resistance gene to a 1.4 Mb interval, based on an estimate using the Hv genome as reference, in populations of only 103 and 146 individuals respectively, similar to what is expected at this locus in barley. The most likely candidate resistance gene within this interval encodes a legume-type lectin-receptor-like protein (LecRLP). Like other LecRLPs that have been implicated in resistance, this gene could be a good candidate for Hb resistance. The reported strategy can be applied as a general strategic approach for identifying genes underlying traits of interest in crop wild relatives.

1739: Designing of a mini-core that effectively represents 3004 diverse accessions of rice
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Posted to bioRxiv 09 Sep 2019

Designing of a mini-core that effectively represents 3004 diverse accessions of rice
231 downloads plant biology

Angad Kumar, Shivendra Kumar, Manoj Prasad, Jitendra K Thakur

Genetic diversity provides foundation for plant breeding and genetic research. As part of the 3K Rice Genome Project, over 3000 rice genomes were recently sequenced. We added four Indian rice accessions to it and made original panel of 3004 accessions. However, large set of germplasms are difficult to preserve and evaluate. Construction of core and mini-core collections is an efficient method for managing genetic resources. This study aims to designing of mini-core comprised of 520 accessions representing original panel. The designed mini-core captured most of the SNPs and represented all phenotypes and geographical regions. The mini-core was validated using different statistical analyses and had representation from all major groups including japonica, indica, aus/boro and aromatic/basmati. GWAS analyses with mini-core panel efficiently reproduced the marker-traits association identified among original 3004 panel. Expression analysis of trait-associated genes highlights the relevance of such mini-core panel. Haplotype analysis could also validate our mini-core panel. Apart from mini-core, we identified few regional and varietal specific marker-trait associations which were not evident in original panel. In this era of large-scale sequencing projects, such a strategy of designing mini-core will be very useful.

1740: ROP INTERACTIVE PARTNER b interacts with the ROP GTPase RACB and supports fungal penetration into barley epidermal cells
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Posted to bioRxiv 29 Aug 2019

ROP INTERACTIVE PARTNER b interacts with the ROP GTPase RACB and supports fungal penetration into barley epidermal cells
231 downloads plant biology

Christopher McCollum, Stefan Engelhardt, Ralph Hückelhoven

RHO of Plants (ROP) G-proteins are key components of cell polarization processes in plant development. The barley (Hordeum vulgare) ROP protein RACB, is a susceptibility factor in the interaction of barley with the barley powdery mildew fungus Blumeria graminis f.sp. hordei (Bgh). RACB also drives polar cell development, and this function might be coopted during formation of fungal haustoria in epidermal cells of barley. In order to understand RACB signaling during the interaction of barley with Bgh, we searched for potential downstream interactors of RACB. Here, we show that ROP INTERACTIVE PARTNER b (RIPb) directly interacts with RACB in yeast and in planta. Over-expression of RIPb supports susceptibility of barley to Bgh. RIPb further interacts with itself at microtubules. However, the interaction with activated RACB takes place at the plasma membrane. Both, RIPb and RACB are recruited to the site of fungal attack around the neck of developing haustoria suggesting locally enhanced ROP activity. We further assigned different functions to different domains of the RIPb protein. The N-terminal coiled-coil CC1 domain is required for microtubule localization, while the C-terminal coiled-coil CC2 domain is sufficient to interact with RACB and to fulfill a function in susceptibility at the plasma membrane. Hence, RIPb appears to locate at microtubules and is then recruited by activated RACB for a function at the plasma membrane during formation of the haustorial complex.

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