Plant Diversity ›› 2020, Vol. 42 ›› Issue (05): 370-375.DOI: 10.1016/j.pld.2020.07.003

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A hybrid sterile locus leads to the linkage drag of interspecific hybrid progenies

Mianmian Wanga,b, Jun Yanga,b, Jinpeng Wana,c, Dayun Taod, Jiawu Zhoud, Diqiu Yua,c, Peng Xua,c   

  1. a Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, 650223, Yunnan, China;
    b University of Chinese Academy of Sciences, Beijing, 100049, China;
    c Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, Menglun, Mengla, 666303, Yunnan, China;
    d Yunnan Key Laboratory for Rice Genetic Improvement, Food Crops Research Institute, Yunnan Academy of Agricultural Sciences, Kunming, 650200, Yunnan, China
  • Received:2020-03-26 Revised:2020-07-16 Online:2020-10-25 Published:2020-10-28
  • Contact: Mianmian Wang, Jun Yang, Jinpeng Wan, Dayun Tao, Jiawu Zhou, Diqiu Yu, Peng Xu
  • Supported by:
    The authors thank the Public Technology Service Center, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences for technical support. This work was supported by “One-ThreeFive” Strategic Planning of Chinese Academy of Sciences (2017XTBG-T02) and Strategic Leading Science and Technology Program (XDA24030301 and XDA24040308).

Abstract: Interspecific hybridization plays an important role in rice breeding by broadening access to desirable traits such as disease resistance and improving yields. However, interspecific hybridization is often hindered by hybrid sterility, linkage drag, and distorted segregation. To mine for favorable genes from Oryza glaberrima, we cultivated a series of BC4 introgression lines (ILs) of O. glaberrima in the japonica rice variety background (Dianjingyou 1) in which the IL-2769 (BC4F10) showed longer sterile lemmas, wider grains and spreading panicles compared with its receptor parent, suggesting that linkage drag may have occurred. Based on the BC5F2 population, a hybrid sterility locus, S20, a long sterile lemma locus, G1-g, and a new grain width quantitative trait locus (QTL), qGW7, were mapped in the linkage region about 15 centimorgan (cM) from the end of the short arm of chromosome 7. The hybrid sterility locus S20 from O. glaberrima eliminated male gametes of Oryza sativa, and male gametes carrying the alleles of O. sativa in the heterozygotes were aborted completely. In addition, the homozygotes presented a genotype of O. glaberrima, and homozygous O. sativa were not produced. Surprisingly, the linked traits G1-g and qGW7 showed similar segregation distortion. These results indicate that S20 was responsible for the linkage drag. As a large number of detected hybrid sterility loci are widely distributed on rice chromosomes, we suggest that hybrid sterility loci are the critical factors for the linkage drag in interspecific and subspecific hybridization of rice.

Key words: Interspecific hybridization, Linkage drag, Hybrid sterility, Segregation distortion