Abstract
BackgroundOryza glumaepatula represents an important resource of genetic diversity that can be used to improve rice production. However, hybrid sterility severely restricts gene flow between Oryza species, and hinders the utilization of distant heterosis in hybrid rice breeding.ResultsIn order to fully exploit the beneficial genes of O. glumaepatula and facilitate the conservation of these gene resources, a set of chromosome single-segment substitution lines (SSSLs) was developed using an indica variety HJX74 as the recurrent parent and an accession of O. glumaepatula as the donor parent. During the process of SSSLs development, S23, a locus conferring hybrid male sterility between O. sativa and O. glumaepatula, was identified and fine mapped to 11.54 kb and 7.08 kb genomic region in O. sativa and O. glumaepatula, respectively, encoding three and two candidate ORFs, respectively. qRT-PCR and sequence analysis excluded one common ORF as the candidate gene. In addition, hybrid male sterility caused by S23 was environment-sensitive, and could be observed only in natural short-day (NSD).ConclusionIdentification and candidate genes analysis of S23 in this study provides a valuable example to study the crosstalk between interspecific F1 hybrid male sterility and environment-conditioned male sterility in rice, facilitates reserving and utilizing favorable genes or alleles of wild Oryza species, and allows for a more efficient exploitation of distant heterosis in hybrid rice breeding.
Highlights
Oryza glumaepatula represents an important resource of genetic diversity that can be used to improve rice production
We identified a locus S23 conferring environment-sensitive hybrid male sterility between O. sativa and O. glumaepatula, another wild Oryza species belonging to AA genome group, during the process of the development of segment substitution lines (SSSLs) using an accession of O. glumaepatula as the donor parent
Candidate gene analysis of S23 To define candidate genes for S23, we examined the expression of the three target genes as well as ORF2 in which major sequence differences were found between the two parent genotypes in natural short-day (NSD)
Summary
Oryza glumaepatula represents an important resource of genetic diversity that can be used to improve rice production. Hybrid sterility severely restricts gene flow between Oryza species, and hinders the utilization of distant heterosis in hybrid rice breeding. The limited genetic diversity of cultivated rice renders them more vulnerable to environment and jeopardizes the potential for sustained genetic improvement over the long term (Tanksley and McCouch 1997). The wild species of the genus Oryza serve as a virtually untapped reservoir of genetic diversity that can be used to improve rice production (Brar and Khush 1997). Hybrid sterility, a postzygotic reproductive barrier, is quite common in the hybrid plants which fail to produce fertile pollen or embryo sacs during reproductive development, restricting gene flow between Oryza species, maintaining species identity during speciation and hindering the utilization
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