Identification and functional characterization of Si4CLL1 controlling the male sterility in the sesame GMS mutant, ms1812

Abstract

Sesame (Sesamum indicum L.), 2n = 2x = 26, is an important oilseed crop with high heterosis potential. In this study, we explored the histological and genetic characters and causal gene of a male sterile sesame mutant, ms1812 (ms3). The microspore abortion of ms1812 that led to male sterility occurred at the tetrad stage of microspore development. No normal pollens formed and were observed in anther chambers of ms1812 at the microspore mature stage. With the aid of high‐efficient association mapping and the sesame var. Yuzhi 11 reference genome, we identified the SNP 10505640 on SiChr.3 segregating with the male sterility and the mutated gene, Si4cll1, controlling the recessive male sterility in sesame. Si4CLL1 encodes a 4‐coumarate‐CoA ligase‐like protein. The 1292^th nucleotide (T₁₂₉₂) of Si4CLL1 mutated into A₁₂₉₂, resulting in the amino acid change from Ile₂₃₉ to Lys₂₃₉. Si4CLL1 mainly expressed in young developing buds. Compared with the wild type, the transcript abundance of Si4cll1 in the developing buds of ms1812 reduced significantly, which might affect the phenylpropanoid biosynthesis pathway and finally, the lignin formation of microspore cell wall. These findings provide key new information to deciphering the molecular mechanism underlying male sterility and hybrid variety breeding assisted by male sterility in sesame.

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