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BELL 1 ‐like homeobox genes regulate inflorescence architecture and meristem maintenance in rice

2019; Wiley; Volume: 98; Issue: 3 Linguagem: Inglês

10.1111/tpj.14230

1365-313X

Takuyuki Ikeda, Wakana Tanaka, Taiyo Toriba, Chie Suzuki, Akiteru Maeno, Katsutoshi Tsuda, Toshihiko Shiroishi, Tetsuya Kurata, Tomoaki Sakamoto, Masayuki Murai, Hiroaki Matsusaka, Toshihiro Kumamaru, Hiroyuki Hirano,

Plant Gene Expression Analysis

Summary 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 BELL 1‐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 ‐ LIKE 1 ( RIL 1 ) (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 RIL 1 were involved in regulating the phyllotactic pattern of the pBM s to form normal inflorescences. In addition, both RI and RIL 1 seem to be involved in meristem maintenance, because the ri ril1 double‐mutant failed to establish or maintain the shoot apical meristem during embryogenesis.