BELL1-like homeobox genes regulate inflorescence architecture and meristem maintenance in rice
BELL1-like homeobox genes regulate inflorescence architecture and meristem maintenance in rice
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DOI：
10.1111/tpj.14230
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发表时间：
2019-05-01
期刊：
影响因子：
7.2
通讯作者：
Hirano, Hiro-Yuki
中科院分区：
文献类型：
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作者：
Ikeda, Takuyuki;Tanaka, Wakana;Hirano, Hiro-Yuki
被子植物的花序结构是多样的，主要由枝和花的排列决定，称为叶序。在水稻（Oryza sativa）中，主花序轴，称为花序轴，在螺旋叶序中产生初级分枝，并且在这些分枝上形成花（小穗）。在这里，我们研究了一个经典的突变体，命名为轮生轴（ri），它产生的分支在一个部分轮生叶序。基因分离表明RI编码一个类似于拟南芥PENNYWISE/BELLRINGER/REPLUMLESS的BELL 1型同源域转录因子，并且在花序和分支分生组织内的特定区域表达，在那里它们的后代分生组织将很快启动。RI的近缘种RI-LIKE 1（RIL 1）的一个ri纯合子和一个突变等位基因（RIL 1/+植株）的遗传组合增强了ri花序表型，包括分支叶序和轴节间模式的异常。在花序发育的早期，ri和ri ril 1/+植株的初生分支分生组织（pBM）发生的时间和排列受到干扰。这些结果表明，RI和RIL 1参与调节叶序格局的pBM形成正常的花序。此外，RI和RIL 1似乎都参与分生组织的维护，因为ri ril 1双突变体未能建立或维持芽顶端分生组织在胚胎发生过程中。显著性声明我们发现，两个BELL 1样基因，RI和RIL 1，发挥了至关重要的作用，制定花序结构，通过调节的时间和安排的初级分支分生组织的起始。此外，我们认为这些基因也参与分生组织的维持。
Inflorescence architecture is diverse in angiosperms, and is mainly determined by the arrangement of the branches and flowers, known as phyllotaxy. In rice (Oryza sativa), the main inflorescence axis, called the rachis, generates primary branches in a spiral phyllotaxy, and flowers (spikelets) are formed on these branches. Here, we have studied a classical mutant, named verticillate rachis (ri), which produces branches in a partially whorled phyllotaxy. Gene isolation revealed that RI encodes a BELL1-type homeodomain transcription factor, similar to Arabidopsis PENNYWISE/BELLRINGER/REPLUMLESS, and is expressed in the specific regions within the inflorescence and branch meristems where their descendant meristems would soon initiate. Genetic combination of an ri homozygote and a mutant allele of RI-LIKE1 (RIL1) (designated ri ril1/+ plant), a close paralog of RI, enhanced the ri inflorescence phenotype, including the abnormalities in branch phyllotaxy and rachis internode patterning. During early inflorescence development, the timing and arrangement of primary branch meristem (pBM) initiation were disturbed in both ri and ri ril1/+ plants. These findings suggest that RI and RIL1 were involved in regulating the phyllotactic pattern of the pBMs to form normal inflorescences. In addition, both RI and RIL1 seem to be involved in meristem maintenance, because the ri ril1 double-mutant failed to establish or maintain the shoot apical meristem during embryogenesis.Significance Statement We revealed that two BELL1-like genes, RI and RIL1, play a crucial role in elaborating inflorescence architecture by regulating the timing and arrangement of primary branch meristem initiation. In addition, we suggest that these genes are also involved in meristem maintenance.