References
The Wild Abortive (WA) type and Hong Lian (HL) type are representative
cytoplasms causing male sterility in China. Both were isolated from the common
wild rice (O. rufipogon) collected in Hainen Island. The fertility restorer for
WA lines is a sporophytic gene system, and that for HL lines is a gametophytic
gene system (Li and Zhu 1986; Zhu 1979, 1984). To understand the trend of
geographical distribution of fertility-restoring genes, two male-sterile lines,
WA-Zhen shan 97A and HL-Hua ai 15A, both being Hsien (Indica) types, were each
test-crossed by more than 600 native rice varieties from different localities
of China, and the F\1\ plants were examined for pollen and seed fertilities.
From these results, the varieties tested were classified into restorer (both
pollen and seed fertilities <70%), non-restorer or maintainer (fertilities
<10%), and weak restorer (10-70%) categories. Restorers for HL were more
frequent than those for WA. For both cytoplasm types, the frequency of
restoring genes was high in the southern provinces and the middle reaches of
the Yangtze River (Table 1. Geographical distribution of fertility-restoring
genes for WA and HL cytoplasms in China).
Among the varieties tested, about 160 were Keng (Japonica) types and the rest were Hsien (Indica) types. Almost all Keng varieties were non-restorers for both cytoplasms (Table 1. Geographical distribution of fertility-restoring genes for WA and HL cytoplasms in China). The rarity of restorers in Yunnan, Jiangsu, Zhejiang, Northeast and Northwest regions could be due to the predominance of keng varieties. The F\1\ sterilities observed are due not only to cytoplasmic male sterility but also the genic F\1\ infertility often found in crosses between distantly related rice cultivars. Yet, if the crosses with Keng varieties are excluded, the data may represent the overall trend of distribution of restoring genes.
Table 1. Geographical distribution of fertility-restoring genes for WA and HL
cytoplasms in China
References
Li, Ze-Bing and Ying-Guo Zhu, 1986. Current status of research in rice male- sterile cytoplasm and fertility restoration. Intern. Symp. on Hybrid Rice, Changsha, 6-10 Oct. 1986.
Zhu, Ying-Guo, 1979. Studies on male sterile lines of rice with different cytoplasms. Acta Agronomica Sinica 5(3): 29-38. (in Chinese)
Zhu, Ying-Guo, 1984. Study on relationship between restoring and maintaining of different types of male sterile lines in rice. Hereditas 6(5):14-16. (in Chinese)