Abstract
BackgroundRice (Oryza sativa) panicle architecture is the major determinant of the ideal plant architecture that directly influence yield potential. Many genes influencing development of primary branches, secondary branches, spikelet and pedicel would also influence panicle architecture, which is thus a complex trait regulated by genes from various aspects. miR156, an extensively studied miRNA, has recently emerged as promising target for crop improvement because of its role in plant architecture regulation, such as the number of tillers, plant height and the panicle architecture. Increasing evidence suggests that miR156 might play an important role in panicle architecture regulation.Main bodyTo study the detailed function of miR156 in rice panicle architecture regulation, we examined the genetic interaction or transcriptional regulation of miR156/OsSPL to other panicle regulating genes. Our results revealed that expression of many panicle related genes were influenced by miR156. Through biochemical analysis, we further proved that miR156 directly regulated the axillary meristem regulating gene, LAX1, at the transcription level. And the intimate relations between miR156 and LAX1, and miR156 and LAX2 were also uncovered by genetic analysis. On the other hand, a tight genetic linkage between miR156 and RCN2, the panicle branch promoting gene, was also detected, which suggested a buffering mechanism for the miR156 mediated panicle architecture regulation. Furthermore, genetic analysis also demonstrated that miR156 functioned in the same pathway with OsRA2 to regulate pedicel length.Short conclusionAltogether, miR156 integrates several genetic pathways mediated by genes such as LAX1, LAX2, RCN2 and OsRA2, and comprehensively regulates panicle development in rice. Based on these analysis, we concluded that miR156 acts as an important regulator for panicle architecture through influencing various aspects of panicle development.
Highlights
Sequestering miR156 resulted in sparse panicle with less secondary branches (SB) and longer pedicel In our previous study, it was proved that miR156f regulated plant height and tiller number in rice through the auxin signaling pathway (Dai et al 2018)
We proved that miR156 regulated panicle development, with the cs mutant plants in which miR156f was over expressed showing small panicle, and MIM156fOE plants in which miR156 was downregulated showing increased panicle length and decreased number of SBs, and expression of many genes functioned in panicle regulation was influenced by miR156
We provided genetic evidences to elucidate the relationships between miR156/SQUAMOSA PROMOTER BINDING PROTEIN-like (SPL) module and some panicle development related genes, such as LAX PANICLE 1 (LAX1), LAX PANICLE 2 (LAX2), RCN2 and OsRA2
Summary
As one of the most important cereal crops, rice (Oryza sativa) provides food for more than half of the world population. Two of the four rice RCN genes regulated the transition from shoot apical meristem (SAM) to inflorescence meristem (IM), when overexpressed, the plants showed greatly increased PBs and SBs in the panicle (Nakagawa et al 2002). We proved that miR156 regulated panicle development, with the cs mutant plants in which miR156f was over expressed showing small panicle, and MIM156fOE plants in which miR156 was downregulated showing increased panicle length and decreased number of SBs, and expression of many genes functioned in panicle regulation was influenced by miR156. We revealed the possible relation between miR156 and LAX1, LAX2, RCN2 and OsRA2 Through these analysis, we investigated the possible pathways through which miR156 regulated axillary development, the number of branches, and pedicel development in the panicle
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