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The dynamics of soybean leaf and shoot apical meristem transcriptome undergoing floral initiation process.

Wong CE, Singh MB, Bhalla PL - PLoS ONE (2013)

Bottom Line: A total of 2951 shoot apical meristem and 13,609 leaf sequences with significant profile changes during the time course examined were identified.Transcripts associated with protein degradation were also significantly changing in leaf and SAM implicating their involvement in triggering the developmental switch.Further, evidence is emerging that the conversion of shoot apical meristem to inflorescence meristem is linked with the interplay of auxin, cytokinin and GA creating a low cytokinin and high GA environment.

View Article: PubMed Central - PubMed

Affiliation: Plant Molecular Biology and Biotechnology Group, ARC Centre of Excellence for Integrative Legume Research, Melbourne School of Land and Environment, The University of Melbourne, Parkville, Victoria, Australia.

ABSTRACT
Flowering process governs seed set and thus affects agricultural productivity. Soybean, a major legume crop, requires short-day photoperiod conditions for flowering. While leaf-derived signal(s) are essential for the photoperiod-induced floral initiation process at the shoot apical meristem, molecular events associated with early floral transition stages in either leaves or shoot apical meristems are not well understood. To provide novel insights into the molecular basis of floral initiation, RNA-Seq was used to characterize the soybean transcriptome of leaf and micro-dissected shoot apical meristem at different time points after short-day treatment. Shoot apical meristem expressed a higher number of transcripts in comparison to that of leaf highlighting greater diversity and abundance of transcripts expressed in the shoot apical meristem. A total of 2951 shoot apical meristem and 13,609 leaf sequences with significant profile changes during the time course examined were identified. Most changes in mRNA level occurred after 1short-day treatment. Transcripts involved in mediating responses to stimulus including hormones or in various metabolic processes represent the top enriched GO functional category for the SAM and leaf dataset, respectively. Transcripts associated with protein degradation were also significantly changing in leaf and SAM implicating their involvement in triggering the developmental switch. RNA-Seq analysis of shoot apical meristem and leaf from soybean undergoing floral transition reveal major reprogramming events in leaves and the SAM that point toward hormones gibberellins (GA) and cytokinin as key regulators in the production of systemic flowering signal(s) in leaves. These hormones may form part of the systemic signals in addition to the established florigen, FLOWERING LOCUS T (FT). Further, evidence is emerging that the conversion of shoot apical meristem to inflorescence meristem is linked with the interplay of auxin, cytokinin and GA creating a low cytokinin and high GA environment.

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Related in: MedlinePlus

Expression of putative auxin-related genes in soybean.An overview of auxin regulatory mechanism is given on the left with possible feedback regulations indicated by dashed arrows [56] while expression data of differentially expressed transcripts for respective annotated homologs are given in the right panel. In the nucleus, IAA binds to an F box protein called TIR1 and stabilizes the interaction between TIR1 and transcriptional repressors AUX/IAA proteins, targeting them for proteolysis. STY1, SRS5, SRS5, SRS7 and LRP1 are all members of SHI family of transcription factors with STY1 known to stimulate auxin biosynthesis in Arabidopsis [57]. Expression level is as in Figure 3.
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pone-0065319-g006: Expression of putative auxin-related genes in soybean.An overview of auxin regulatory mechanism is given on the left with possible feedback regulations indicated by dashed arrows [56] while expression data of differentially expressed transcripts for respective annotated homologs are given in the right panel. In the nucleus, IAA binds to an F box protein called TIR1 and stabilizes the interaction between TIR1 and transcriptional repressors AUX/IAA proteins, targeting them for proteolysis. STY1, SRS5, SRS5, SRS7 and LRP1 are all members of SHI family of transcription factors with STY1 known to stimulate auxin biosynthesis in Arabidopsis [57]. Expression level is as in Figure 3.

Mentions: IAA is the most abundantly occurring form of auxin and its level is influenced by its biosynthesis, transport and the hydrolysis or formation of IAA conjugates (Figure 6). The pathways for auxin biosynthesis are yet to be fully elucidated but members of the YUCCA family of flavin monooxygenase-like enzymes have recently been reported to catalyze the rate-limiting step for auxin biosynthesis through a tryptophan-dependent pathway [56].


The dynamics of soybean leaf and shoot apical meristem transcriptome undergoing floral initiation process.

Wong CE, Singh MB, Bhalla PL - PLoS ONE (2013)

Expression of putative auxin-related genes in soybean.An overview of auxin regulatory mechanism is given on the left with possible feedback regulations indicated by dashed arrows [56] while expression data of differentially expressed transcripts for respective annotated homologs are given in the right panel. In the nucleus, IAA binds to an F box protein called TIR1 and stabilizes the interaction between TIR1 and transcriptional repressors AUX/IAA proteins, targeting them for proteolysis. STY1, SRS5, SRS5, SRS7 and LRP1 are all members of SHI family of transcription factors with STY1 known to stimulate auxin biosynthesis in Arabidopsis [57]. Expression level is as in Figure 3.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3675103&req=5

pone-0065319-g006: Expression of putative auxin-related genes in soybean.An overview of auxin regulatory mechanism is given on the left with possible feedback regulations indicated by dashed arrows [56] while expression data of differentially expressed transcripts for respective annotated homologs are given in the right panel. In the nucleus, IAA binds to an F box protein called TIR1 and stabilizes the interaction between TIR1 and transcriptional repressors AUX/IAA proteins, targeting them for proteolysis. STY1, SRS5, SRS5, SRS7 and LRP1 are all members of SHI family of transcription factors with STY1 known to stimulate auxin biosynthesis in Arabidopsis [57]. Expression level is as in Figure 3.
Mentions: IAA is the most abundantly occurring form of auxin and its level is influenced by its biosynthesis, transport and the hydrolysis or formation of IAA conjugates (Figure 6). The pathways for auxin biosynthesis are yet to be fully elucidated but members of the YUCCA family of flavin monooxygenase-like enzymes have recently been reported to catalyze the rate-limiting step for auxin biosynthesis through a tryptophan-dependent pathway [56].

Bottom Line: A total of 2951 shoot apical meristem and 13,609 leaf sequences with significant profile changes during the time course examined were identified.Transcripts associated with protein degradation were also significantly changing in leaf and SAM implicating their involvement in triggering the developmental switch.Further, evidence is emerging that the conversion of shoot apical meristem to inflorescence meristem is linked with the interplay of auxin, cytokinin and GA creating a low cytokinin and high GA environment.

View Article: PubMed Central - PubMed

Affiliation: Plant Molecular Biology and Biotechnology Group, ARC Centre of Excellence for Integrative Legume Research, Melbourne School of Land and Environment, The University of Melbourne, Parkville, Victoria, Australia.

ABSTRACT
Flowering process governs seed set and thus affects agricultural productivity. Soybean, a major legume crop, requires short-day photoperiod conditions for flowering. While leaf-derived signal(s) are essential for the photoperiod-induced floral initiation process at the shoot apical meristem, molecular events associated with early floral transition stages in either leaves or shoot apical meristems are not well understood. To provide novel insights into the molecular basis of floral initiation, RNA-Seq was used to characterize the soybean transcriptome of leaf and micro-dissected shoot apical meristem at different time points after short-day treatment. Shoot apical meristem expressed a higher number of transcripts in comparison to that of leaf highlighting greater diversity and abundance of transcripts expressed in the shoot apical meristem. A total of 2951 shoot apical meristem and 13,609 leaf sequences with significant profile changes during the time course examined were identified. Most changes in mRNA level occurred after 1short-day treatment. Transcripts involved in mediating responses to stimulus including hormones or in various metabolic processes represent the top enriched GO functional category for the SAM and leaf dataset, respectively. Transcripts associated with protein degradation were also significantly changing in leaf and SAM implicating their involvement in triggering the developmental switch. RNA-Seq analysis of shoot apical meristem and leaf from soybean undergoing floral transition reveal major reprogramming events in leaves and the SAM that point toward hormones gibberellins (GA) and cytokinin as key regulators in the production of systemic flowering signal(s) in leaves. These hormones may form part of the systemic signals in addition to the established florigen, FLOWERING LOCUS T (FT). Further, evidence is emerging that the conversion of shoot apical meristem to inflorescence meristem is linked with the interplay of auxin, cytokinin and GA creating a low cytokinin and high GA environment.

Show MeSH
Related in: MedlinePlus