Improving Blast Resistance Of Dual-purpose Genic Sterile Line In Rice Using Molecular Marker-assisted Selection

Rice, which is a staple food crops with the largest planted area in China, played an irreplaceable role by other crops in ensuring food security issues. Rice blast, which is caused by ascomycetes Magnaporthe grisea (Hebert) Barr, is one of the most devastating rice disease continued occurred all over the world. To breed rice varieties with resistance to rice blast, is the most effective, economical and environment-friendly strategy to control this disease.Recently, eight genes, which include Pi9, Pi25, Pigm, Pi47, Pi48, Pi49, Pi2-1and Pi51(t), have been identified as the dominant and main effect rice blast gene with broad-spectrum resistance. Furthermore, all these rice blast gene have been fine mapped or cloned. In this study,75-1-127(donor of Pi9), GuMei2(GM2, donor of Pi25), GuMei4(GM4, donor of Pigm), Tianjinyeshengdao (TY, donor of Pi2-1and Pi51(t)), Xiangzi3150(XZ, donor of Pi47and Pi48) and Mowanggu(MWG, donor of Pi49) were used as the donor parents of the resistance gene. Six elite photo-thermo sensitive genic male sterile line including099S, C815S,191S,9771S,236S and Guangzhan63S(GZS), were used as receptor parents. The resistant gene provided by six rice varieties with broad-spectrum resistance, were introduced into the six photo-thermo sensitive genic male sterile lines, respectively, by using backcross and molecular marker-assisted selection technology. The agronomic traits of BC3F1were investigated, and the resistance of the corresponding BC3F2were evaluated by inoculating with two blast isolates, namely110-2and CHL506, which collected from Hunan and Fujian Province respectively. The main results are as follows:1. Six SSR markers including RM7311, RM7178, RM3330, RM224, RM27990and LY2, which showed obvious and stable polymorphism between any crosses of donor and receptor parents, were screened and used to analysis the target genes, respectively.2. BC3F2plants, which harbor at least one resistant gene based the genetic background of one of the six receptor sterile lines, respectively, were havested, by using backcross method combining with marker assited selected technology. For each of the six photo-thermo sensitive genic male sterile line, BC3F2plants contain any one or two gene of Pi9, Pi25, Pigm, Pi49, Pi47, Pi48, Pi2-1and Pi51, were bred.3. The major agronomic traits, which include days to heading, plant height, panicle length, number of panicles per plant, flag leaf length, flag leaf width and number of grains per panicle, of the improved BC3F1were investigated. The results showed that there were no significant differences between the receptor parent and BC3F1genenations for most of agronomic traits, except that part of the BC3F1plant with much grains per panicle than that of the correspording receptor parents.4. Two blast isolates,110-2and CHL506, collected from Hunan and Fujian Province, were used to inoculate the improved lines of BC3F2genenations. The results showed that the resistance gene have been introduced into the recepter parents, thus validated the molecular marker-assisted selection blast resistance gene is effective in this study.