Identification and confirmation of three neutral alleles conferring wide compatibility in inter...
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L.) using near-isogenic lines G. W. Wang (1), Y. Q. He (1), C. G. Xu (1) and Qifa Zhang (1) (1) National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan, 430070, China Received: 17 February 2005 Accepted: 22 April 2005 Published online: 1 June 2005 Issue: Volume 111, Number 4 Date: August 2005 Pages: 702 - 710 Communicated by C. Mllers Abstract Wide-compatibility varieties (WCVs) are a special class of rice germplasm that is able to produce fertile hybrids when crossed to both indica and japonica subspecies. Previous studies determined 'Dular' and 02428 as two WCVs and identified a number of QTLs as having large effects on fertility of inter-subspecific hybrids. In this study, we developed five near-isogenic lines (NILs) for three of the QTLs, f5, f6 and S5, by backcrossing and marker-assisted selection, using 'Dular' and 02428 as the donors and 'Zhenshan 97' as the recipient. Three of the NILs each carried one introgressed allele, and two NILs each carried two introgressed alleles in combinations. The NILs were testcrossed to an indica tester 'Nanjing 11' and a japonica tester 'Balilla'. The results showed that the f5 allele from 'Dular' (f5-Du) is a neutral allele conferring wide compatibility, with a large effect on both pollen and spikelet fertility, and the f6 allele from 'Dular' (f6-Du) is a neutral allele for spikelet fertility with smaller effect. The S5 allele from 02428 (S5-08) was confirmed to be a neutral allele for spikelet fertility. It is likely that f6 and S5 are the same locus as deduced by their genomic locations and effects. The results also showed that even in combination, two neutral alleles of different loci were not able to produce normal fertility hybrids in typical indicajaponica crosses. The implications of the findings in rice breeding programs are discussed. -------------------------------------------------------------------------------- Qifa Zhang Email: Phone: +86-27-87282429 Fax: 86-27-87287092