Development and evaluation of improved lines based on an elite rice variety 9311 for overcoming hybrid sterility in rice
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Development and evaluation of improved lines based on an elite rice variety 9311 for overcoming hybrid sterility in rice Xiaojuan Ma & Xin Wei & Guanjun Gao & Haichao Jiang
Received: 18 June 2020 / Accepted: 30 September 2020 # Springer Nature B.V. 2020
Abstract Hybrid sterility is a major obstacle to the development of superior inter-subspecific hybrids between indica and japonica subspecies of Asiancultivated rice. To overcome hybrid sterility, we introduced four japonica alleles (S-j) at Sa, Sc, f5, and S32 loci from Nipponbare into 9311 through marker-assisted backcross breeding, and four improved lines were obtained. Three wide-compatibility lines 9311(S5-n), 9311(f5-n), and 9311(S5-n+f5-n) previously constructed were used as control and parental line of hybridization. By crossing with 9311(S5-n+f5-n), two pyramiding lines 9311(Sa+S5-n+f5-n) and 9311(S32+Sa+S5-n+f5n) were obtained. To evaluate the gene effect of pollen fertility and spikelet fertility, the near-isogenic lines (NILs) harboring S5-n, f5-n, Sa, Sc, f5, or S32 and three pyramiding lines with S5-n+f5-n, Sa+S5-n+f5-n, or S32+Sa+S5-n+f5-n were testcrossed to six japonica varieties. The results showed that single-gene f5, f5-n, S32, and S5-n could significantly improve spikelet fertility in majority of indica-japonica hybrids. Single-gene Sa and Sc could significantly improve spikelet fertility in part of indica-japonica hybrids. Moreover, the pyramiding lines exhibited significantly higher spikelet fertility than
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11032-020-01180-2) contains supplementary material, which is available to authorized users. X. Ma : X. Wei : G. Gao : H. Jiang (*) National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China e-mail: [email protected]
the control in indica-japonica hybrids. A significant increase in spikelet fertility (31.4–55%) was observed in three- or four-gene pyramiding lines. Our results provide an effective approach to exploiting heterosis between indica and japonica subspecies, which had a profound implication in rice breeding. Keywords Rice . Hybrid sterility . Heterosis . Improved lines . Fertility
Introduction Rice (Oryza sativa L.) is one of mankind’s major staple food for more than half of the world’s population (Khush 2005; Zhang et al. 2011). World rice yield increased at a rate of 2.3 to 2.5% per year during the 1970s and 1980s. However, the yield growth rate for rice has been declining during the last decades, in contrast to the continuous increase in populations in major rice-consuming countries (Jeon et al. 2011). Therefore, it is of immense importance to develop rice cultivars possessing high yield and yield stability to feed a growing world population (Fan et al. 2011). Asian-cultivated rice comprises two main subspecies, indica and japonica. The inter-subspecific hybrid between distinct indica and japonica rice, namely indica-japonic
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