Breeding of the Dormant Thermosensitive Genic Male-Sterile Lines of Early Rice to Overcome Pre-Harvest Sprouting of the Hybrid Seeds
2018
Xiaoyu Chen | Yun Tian | Xiangyang Lu
The pollen development of male-sterile lines should be conducted during the high temperature season to ensure the sterility of male-sterile line pollen and the safety of hybrid seed production in the breeding of thermosensitive genic male-sterile (TGMS) lines of early rice. However, the mature hybrid rice seeds are prone to pre-harvest sprouting (PHS) during hot, rainy days, which leads to the decrease of hybrid rice seed quality or a loss of utilization value. In this study, with an aim to bring a dormancy trait from the dormant genotype to the current low-dormant TGMS lines, a common wild rice &ldquo:Chaling&rdquo: (Oryza rufipogon), which has strong seed dormancy, a large black stigma, and a high exsertion rate, was hybridized with the early rice TGMS line &ldquo:Zhu 1S,&rdquo: which often exhibits PHS. After screening for early maturing and seed dormancy, the early rice &ldquo:Yezao S&rdquo: and &ldquo:Yezhuzao S,&rdquo: with the characteristic of seed dormancy, were selected. The critical temperature of high temperature sterility for these two male-sterile lines was below 23.5 °:C. The stigma of &ldquo:Yezao S&rdquo: was black and its exsertion rate was 79.9%, while &ldquo:Yezhuzao S&rdquo: had a colorless stigma with an exsertion rate of 76.8%. The expression of the genes OsNCEDs in &ldquo:Yezao S&rdquo: and &ldquo:Yezhuzao S&rdquo: were significantly higher than that in &ldquo:Zhu 1S&rdquo: the 15th day after heading, and the abscisic acid (ABA) content was also higher than that of &ldquo:Zhu 1S&rdquo: the 20th day after heading. The results indicated that introducing the dormancy characteristics from wild rice &ldquo:Chaling&rdquo: into the early rice TGMS lines was an effective way to prevent PHS.
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