Gene mapping and candidate gene analysis of multi‐grains 1 (Mg1) in rice
2020
Zhang, Ting | Yau, Ching | Zeng, Xiaoqin | Yu, Guoling | Zhang, Yi | Li, Yidan | Ye, Li | Yao, Wanyue | Tu, Yujie | Ling, Yinghua | Yao, Hesheng | He, Guanghua | Li, Yunfeng
As the basic unit of rice (Oryza sativa L.) inflorescence, the spikelet has a profound influence on grain size, weight, and yield. However, the molecular mechanism that underlies the development of spikelets has never been fully elucidated. In this study, we characterized a rice spikelet mutant, multi‐grains 1 (mg1), which was derived from treatment of ‘Xinong 1B’ with ethyl methanesulfonate. In the mg1 mutant, the spikelet developed two florets with an extra lemma‐like organ and an increased number of inner floral organs. Notably, the spikelet could produce multi‐grains. These phenotypes reflect the considerable potential of using mg1 as a means of increasing rice yield. Genetic analysis revealed that the mg1 phenotype is controlled by a single recessive gene. The MG1 gene was mapped to the interval between simple sequence repeat (SSR) markers RM20754 and RM494 on chromosome 6 within a physical region of 121.57 kb. Sequencing analysis identified a single‐nucleotide substitution from G to A within Os06g0717200 (which corresponds to FLORAL ORGAN NUMBER 1 [FON1]), causing an amino acid mutation of Gly‐869 to Asp‐869 in the mg1 mutant. This finding suggests that MG1 may be a novel allele of FON1. MG1 is involved in the development of spikelet determinacy and floral organs by regulating the expression of genes associated with these characteristics. The present results detail a novel function of MG1, which may facilitate the breeding of rice cultivars with increased numbers of grains per panicle.
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