Dataset Information

TasiRNA-ARF pathway moderates floral architecture in Arabidopsis plants subjected to drought stress.

ABSTRACT: In plants, miRNAs and siRNAs, such as transacting siRNAs (ta-siRNAs), affect their targets through distinct regulatory mechanisms. In this study, the expression profiles of small RNAs (smRNAs) in Arabidopsis plants subjected to drought, cold, and high-salinity stress were analyzed using 454 DNA sequencing technology. Expression of three groups of ta-siRNAs (TAS1, TAS2, and TAS3) and their precursors was downregulated in Arabidopsis plants subjected to drought and high-salinity stress. Analysis of ta-siRNA synthesis mutants and mutated ARF3-overexpressing plants that escape the tasiRNA-ARF target indicated that self-pollination was hampered by short stamens in plants under drought and high-salinity stress. Microarray analysis of flower buds of rdr6 and wild-type plants under drought stress and nonstressed conditions revealed that expression of floral development- and auxin response-related genes was affected by drought stress and by the RDR6 mutation. The overall results of the present study indicated that tasiRNA-ARF is involved in maintaining the normal morphogenesis of flowers in plants under stress conditions through fine-tuning expression changes of floral development-related and auxin response-related genes.

SUBMITTER: Matsui A

PROVIDER: S-EPMC4160631 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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tasiRNA-ARF pathway moderates floral architecture in Arabidopsis plants subjected to drought stress.

Matsui Akihiro A Mizunashi Kayoko K Tanaka Maho M Kaminuma Eli E Nguyen Anh Hai AH Nakajima Maiko M Kim Jong-Myong JM Nguyen Dong Van DV Toyoda Tetsuro T Seki Motoaki M

BioMed research international 20140826

In plants, miRNAs and siRNAs, such as transacting siRNAs (ta-siRNAs), affect their targets through distinct regulatory mechanisms. In this study, the expression profiles of small RNAs (smRNAs) in Arabidopsis plants subjected to drought, cold, and high-salinity stress were analyzed using 454 DNA sequencing technology. Expression of three groups of ta-siRNAs (TAS1, TAS2, and TAS3) and their precursors was downregulated in Arabidopsis plants subjected to drought and high-salinity stress. Analysis o ...[more]

PMID: 25243128

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Project description:BACKGROUND: Drought is a major constraint that leads to extensive losses to agricultural yield worldwide. The potential yield is largely determined during inflorescence development. However, to date, most investigations on plant response to drought have focused on vegetative development. This study describes the morphological changes of reproductive development and the comparison of transcriptomes under various drought conditions. RESULTS: The plants grown were studied under two drought conditions: minimum for successful reproduction (45-50% soil water content, moderate drought, MD) and for survival (30-35%, severe drought, SD). MD plants can produce similar number of siliques on the main stem and similar number of seeds per silique comparing with well-water plants. The situation of SD plants was much worse than MD plants. The transcriptomes of inflorescences were further investigated at molecular level using microarrays. Our results showed more than four thousands genes with differential expression under severe drought and less than two thousand changed under moderate drought condition (with 2-fold change and q-value < 0.01). We found a group of genes with increased expression as the drought became more severe, suggesting putative adaptation to the dehydration. Interestingly, we also identified genes with alteration only under the moderate but not the severe drought condition, indicating the existence of distinct sets of genes responsive to different levels of water availability. Further cis-element analyses of the putative regulatory sequences provided more information about the underlying mechanisms for reproductive responses to drought, suggesting possible novel candidate genes that protect those developing flowers under drought stress. CONCLUSIONS: Different pathways may be activated in response to moderate and severe drought in reproductive tissues, potentially helping plant to maximize its yield and balance the resource consumption between vegetative and reproductive development under dehydration stresses.

Project description:In eukaryotes, GTP-bound ARF GTPases promote intracellular membrane traffic by mediating the recruitment of coat proteins, which in turn sort cargo proteins into the forming membrane vesicles. Mammals employ several classes of ARF GTPases which are activated by different ARF guanine-nucleotide exchange factors (ARF-GEFs). In contrast, flowering plants only encode evolutionarily conserved ARF1 GTPases (class I) but not the other classes II and III known from mammals, as suggested by phylogenetic analysis of ARF family members across the five major clades of eukaryotes. Instead, flowering plants express plant-specific putative ARF GTPases such as ARFA and ARFB, in addition to evolutionarily conserved ARF-LIKE (ARL) proteins. Here we show that all eight ARF-GEFs of Arabidopsis interact with the same ARF1 GTPase, whereas only a subset of post-Golgi ARF-GEFs also interacts with ARFA, as assayed by immunoprecipitation. Both ARF1 and ARFA were detected at the Golgi stacks and the trans-Golgi network (TGN) by both live-imaging with the confocal microscope and nano-gold labeling followed by EM analysis. ARFB representing another plant-specific putative ARF GTPase was detected at both the plasma membrane and the TGN. The activation-impaired form (T31N) of ARF1, but neither ARFA nor ARFB, interfered with development, although ARFA-T31N interfered, like ARF1-T31N, with the GDP-GTP exchange. Mutant plants lacking both ARFA and ARFB transcripts were viable, suggesting that ARF1 is sufficient for all essential trafficking pathways under laboratory conditions. Detailed imaging of molecular markers revealed that ARF1 mediated all known trafficking pathways whereas ARFA was not essential to any major pathway. In contrast, the hydrolysis-impaired form (Q71L) of both ARF1 and ARFA, but not ARFB, had deleterious effects on development and various trafficking pathways. However, the deleterious effects of ARFA-Q71L were abolished by ARFA-T31N inhibiting cognate ARF-GEFs, both in cis (ARFA-T31N,Q71L) and in trans (ARFA-T31N + ARFA-Q71L), suggesting indirect effects of ARFA-Q71L on ARF1-mediated trafficking. The deleterious effects of ARFA-Q71L were also suppressed by strong over-expression of ARF1, which was consistent with a subset of BIG1-4 ARF-GEFs interacting with both ARF1 and ARFA. Indeed, the SEC7 domain of BIG5 activated both ARF1 and ARFA whereas the SEC7 domain of BIG3 only activated ARF1. Furthermore, ARFA-T31N impaired root growth if ARF1-specific BIG3 was knocked out and only ARF1- and ARFA-activating BIG4 was functional. Activated ARF1 recruits different coat proteins to different endomembrane compartments, depending on its activation by different ARF-GEFs. Unlike ARF GTPases, ARF-GEFs not only localize at distinct compartments but also regulate specific trafficking pathways, suggesting that ARF-GEFs might play specific roles in traffic regulation beyond the activation of ARF1 by GDP-GTP exchange.

Dataset Information

TasiRNA-ARF pathway moderates floral architecture in Arabidopsis plants subjected to drought stress.

Publications

tasiRNA-ARF pathway moderates floral architecture in Arabidopsis plants subjected to drought stress.

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