Using bulked extremes and recessive class to map genes for photoperiod-sensitive genic male sterility in rice.

Abstract

Photoperiod-sensitive genie male sterile (PS-GMS) rice has a number of desirable characteristics for hybrid rice production. In this study we made use of a published rice genetic linkage map to determine the locations ofPSGMS genes and we have characterized the effects of these genes on sterility by using molecular markers. A two-step approach was designed for maing the genes: (i) Identifying possible PSGMS gene-containig chromosome regions with bulked DNA from extreme fertile and extreme sterile plants of a very large F2 population and (i) determining the map locations of the genes in extreme sterile individuals. We show that this mapping method is much more cost effective and statistay efficient than using a random sample of an F2 population. We idented two chromosomal regions each containing a PSGMS locus, one designatedpmsl on chromosome 7 and one desinatedpms2 on chromosome 3. The existence of these two loci was confirmed by a large sample assay and with data on ratooning progenies of the F2 plants. A marker-based analysis shows that the effect of pms) is 2-3 times larger than that of pms2 and that dominance is almost complete at both loci. Implications in the breeding of PSGMS rice lines are discussed.A photoperiod-sensitive genic male sterile (PSGMS) rice was found in 1973 as a spontaneous mutant in ajaponica (Oryza sativa ssp. japonica) rice cultivar (Nongken 58) grown in Hubei Province, China (1). Large numbers of studies conducted in the last decade have established that this novel mutant (referred to as Nongken 58S) possesses a number of desirable characteristics that might be useful in hybrid rice (2): pollen fertility of Nongken 58S is regulated by photoperiod length (3); it is completely sterile when grown under long-day conditions, whereas pollen sterility varies when it is grown under short-day conditions; and the critical stage comes between secondary branch differentiation and microsporogenesis during panicle development (4). Thus, PS-GMS rice can be used to propagate itself under short-day conditions and also to produce hybrid seeds by interplanting it with normal fertile lines under long-day conditions. PSGMS rice may therefore provide opportunity to replace the widely used "three-line" (male sterile, maintainer,, and restorer) system with a "two-line" system that promises to greatly reduce costs in labor, time, and resources in hybrid rice production. PSGMS rice has a broad spectrum ofrestoration; almost all normal rice strains restore the fertility of the F1 hybrid. Deliberately bred restorer lines are consequently not required. Fertility is controlled by a relatively simple genetic system, usually one or two major Mendelian loci (1, 5). Thus it should be relatively easy to develop new PSGMS lines by transferring the PSGMS alleles from one genetic background to another, particularly if marker-aided systems of transfer can be developed. A further advantage is that the performance of PSGMS hybrids does not suffer from adverse effects of male sterile cytoplasm such as has commonly been...

Fine mapping and candidate gene prediction of the photoperiod and thermo-sensitive genic male sterile gene pms1(t) in rice

“…This locus was designated as pms3 (Mei et al, 1999a;1999b), and was delimited into a 28.4-kb interval on chromosome 12 (Lu et al, 2005). In contrast, the fertility trait of 32001S, an indica PGMS line also derived from Nongken 58S, displays a two-locus segregation pattern in the progeny resulting from a cross with the indica cultivar Minghui 63 (Zhang et al, 1994), indicating that the fertility trait segregation is dependent on the genetic backgrounds of the materials used in the crosses. The two loci were designated as pms1 and pms2, and were localized on chromosomes 7 and 3, respectively.…”

“…LOC_Os07g12130, 12140, 12160, 12170, and 12240 were used as the candidate genes, and ubiquitin as a control in our experiment PTGMS varieties derived from Nongken 58S was controlled by two recessive genes. The PGMS genes of the line 32001S consist of the two gene loci (pms1 and pms2), of which the pms1 gene was located on chromosome 7 (Zhang et al, 1994;Mei et al, 1999b;Liu et al, 2001;Lu et al, 2005), and another pms3 gene on chromosome 12 (Lu et al, 2005). Localization studies showed that the TGMS genes from different sources may be located in different chromosomes.…”

“…Linkage between molecular markers and the PTGMS gene was determined following bulkedextreme and recessive-class approaches (Zhang et al, 1994). Fertile (BF pool) and sterile (BS pool) DNA bulks were prepared by mixing equal amounts of DNA from 10 highly fertile (>95% fertile pollen) plants and 10 completely sterile (100% sterile pollen) plants, respectively.…”

“…The two loci were designated as pms1 and pms2, and were localized on chromosomes 7 and 3, respectively. The effect of pms1 was found to be two to three times larger than that of pms2 (Zhang et al, 1994). Liu et al (2001) constructed a physical map of the pms1 region and further localized the pms1 locus to an 85-kb region on chromosome 7.…”

Characterization and molecular mapping of RsrR, a resistant gene to maize head smut

“…The SSR marker umc1331 was considered as a potential linkage marker of the RsrR gene. Then the linkage relationship was checked and confirmed by analyzing with 150 susceptible F 2 individuals (Zhang et al 1994). Results indicated that umc1331 was really linked to the resistant gene RsrR (Fig.…”