【作者】 王建龙；

【导师】 袁隆平；

【作者基本信息】 湖南农业大学 ， 作物遗传育种， 2011， 博士

【摘要】 稻瘟病广泛发生在水稻栽培的国家和地区,每年都造成严重损失。迫于寄主的选择压力,稻瘟菌生理小种的致病力往往迅速变异,容易导致主栽品种抗性丧失。因此,新抗病种质资源的发掘、研究和利用是当今水稻抗瘟育种的重要课题,继续选育高产、优质、抗性强、适应性广的突破性新品种仍是今后水稻育种攻关的主要目标。本文对龙S的农艺性状、育性转换规律、异交特性、稻瘟病抗性表现、稻瘟病抗性杂种优势、抗稻瘟病基因的遗传特征及稻瘟病抗性基因定位等方面进行研究,得出主要结果如下：1.龙S具有理想的株叶形态,剑叶长度在35～43cm之间,剑叶张开角度为6.9°,具有长、直、窄等特点。2.龙S属于光温敏核不育系,温度对其育性起主导作用,高温诱导不育,低温诱导可育,不育临界温度为22.5～22.8℃,育性生理临界温度为17.2℃左右,最适宜的繁种温度为19～21.5℃,通过连续两年在长沙地区分期播种试验,其育性稳定,未出现波动。3.龙S异交特性优良,其盛花期主要集中在抽穗后2～6d,花时早,午前花率高,最高达到59.09%,日开花高峰期为09：00～14：00；颖花张开角度为30.64°,张开时间达2.5h；柱头生命力强且持续时间长(5d),柱头外露率高,且双边外露率高于单边外露率,包颈粒率低,异交特性较好,龙S包颈低,只有3.3%,对“九二○”反应较敏感,彻底解除抽穗包颈的用量为15～20/667m2,最适喷施时期为稻穗即将破口期。4.龙S具有广谱抗稻瘟病特性,在鉴定的41份国内外稻瘟菌小种中,龙S的抗性频率达到100%,尤其对于湖南本地的生理小种具有高水平抗性。5.通过对龙S、C815S与8个父本所配组合进行室内及田间的稻瘟病抗性鉴定,与C815S相比,龙S能显著提高杂种F1代稻瘟病抗性水平,所配组合在田间和室内都表现抗病。6.通过群体遗传分析,龙S/CO39的F2群体对稻瘟菌菌株IC-17的抗感单株数分离比符合15：1,说明龙S至少含有2对主效抗瘟基因；龙S/CO39及龙S/NPB的F2群体对稻瘟菌菌株318-2及RB7的抗感株系数分离比均符合3：1,说明龙S对这两个菌株的抗性分别为独立遗传的显性单基因控制。7.利用848对SSR和SNP引物分析龙S与CO39,NPB之间的多态性,结果表明龙S与CO39之间共有多态引物142对,平均多态检出率为16.75%,龙S与NPB之间共检出多态引物287对,多态检出率为33.84%。8.构建龙S与感病亲本NPB杂交F2群体,接种稻瘟菌生理小种318-2进行表型鉴定,采用BSA(Bulk Segregant Analysis)及RCA (Recessive Class Analysis)分析方法将龙S的主效抗瘟基因定位于标记M1与M2之间,距离为1.3cM,这两个标记的物理距离分别位于克隆AP005593同AP005811之间,距离为110kb。通过比较龙S与以前在该位点定位的两个基因Pi5和Pii的抗谱,发现龙S表现出更高更广谱的抗性,结果表明龙S可能具有新的抗瘟等位基因。9.利用龙S与感病亲本CO39杂交构建F2群体,并经单粒传种方法构建F3RIL至F6RIL,构建了一份含112个标记的龙S完整遗传连锁图,并结合田间表型,统计分析发现,龙S的田间抗性由8个QTL控制,分别位于：第5号染色体的标记RM8039与RM18516之间,第6号染色体的标记RM190与RM19410之间,第10号染色体的标记RM5304与RM304之间。综上所述,龙S具有理想的株叶形态,较低的育性敏感期,优良的异交特性,对稻瘟病表现高抗,是一个理想的两系不育系,本研究精细定位了一个未被报道的广谱抗瘟基因Pi-LS(t)及多个微效基因,为这些基因的克隆及分子辅助育种应用奠定了基础。更多还原

【Abstract】 Photoperiod and thermo-sensitive genie male sterile (PTGMs) rice plays an important role in hybrid rice breeding. In this study, we sistimaticly evaluated the agronomy traits, critical sterility temperature point, out-crossing characteristic, the broad-spectrum resistance to rice blast fungus of a two-line male sterile line LongS breeded by Rice Institute of Hunan Agricultural University, and also molecularly mapped one major blast resistance gene Pi-LS(t). The main results are presented as follows.1. The LongS posesses an ideal plant architecture with a length of 35-43 cm and a 6.9°of opening angle for flag leaf.2. LongS is a typical photoperiod and thermo-sensitive genie male sterile line. Temperature is the leading factor for its sterility transistion. The critical sterility temperature point is between 22.5 to 22.8℃, and the physiology sterility temperature is around 17.2℃, the suitable growing temperature for seed increasing is between 19.0 to 21.5℃.3. LongS shows an out-crossing superiority. Its peak flowering period is 2 to 6 days after heading. The flowering rate before noon is about 59.09%. The peak daily-flowering period is at 09:00 to 14:00. The opening angle of flower is about 30.64°, and the flowering time lasts 2.5 hours. Its stigma has a strong vitality insisted for 5 days. The stigma exposed rate is high. The clasping spikelet rate is about 3.3%. LongS is sensitive to GA3 which used for releasing the clasping spikelet, the optimal concentration is 15-20 g/667 m2, and the optimal spraying time is on the point of crevasse.4. The rice blast resistance evaluation showed that LongS is highly resistant to all 41 rice blast isolates collected from China and four foreign countries and is a elite rice blast resistace germplasm.5. The investigation of hybrids resistance using LongS as female line, and another PTGM line C815S as a control, the results indicated that the F1 hybrids originated from the cross between LongS and 8 male parents show a higher rice blast resistance compared to the combinations of C815S.6. The genetic analysis using two F2 population derived from the resistant parent of LongS and the susceptible parent of CO39, NPB showed that the segregation ratio of F2 population derived from cross between LongS with CO39 by inoculation with isolate IC-17 is 15 to 1, suggesting that LongS resistance to race IC-17 are controlled by two resistance genes. The segregation ratios of F2 populations crossed between LongS and CO39 or NPB by inoculation with 318-2 and RB7 respectively is 3 to 1, indicating LongS resistance to race 318-2 or RB7 is controlled by single dominant resistance gene.7. A total of 848 SSR and SNP markers were used to evaluate the genomic polymorphism between LongS and CO39 or NPB for futher rice blast R gene mapping. the results showed that 142 polymorphic markers were identified between LongS and CO39 with a percentage of 16.75% of the tested markers; and 287 were identified from LongS and NPB with a percentage of 33.84% of the tested markers.8. To molecularly map the R gene from LongS, a F2 population crossed by LongS and NPB was used for phenotyping inoculated with a isolate 318-2. and the susceptible plants DNA were genotyped with 287 polymorphic markers through BSA and RCA methods. The linkgae analysis indicated that the R gene was linked to two makers M1 and M2 on chromosome 9 within an interval of 1.3 cM. The gene was temperally designated Pi-LS(t). The resistance spectrum comparasion with two previously mapped R genes Pi5 and Pii on this locus showed that LongS express much more broader resistance spectrum than Pi5 and Pii, suggested that Pi-LS(t) may be a new blast R allelic gene.9. A F6RILs population derived from cross of LongS and CO39 was used for genotyping using 114 SSR and SNP markers, a total of 1522.1 cM genetic linkage map was constructed with 23 linkage groups. To futher identify the blast resistance QTLs, the field blast resistance phenotype was evaluated. Combining the phenotype and genotype data,8 minor QTLs were detected using the composite interval mapping (CIM) method, of which located on chromosome 5 between the marker RM8039 and RM18516; chromosome 6 in the interval of marker RM190 and RM19410 and chromosome 10 between the marker RM5304 and RM304.Take together with above results, our data indicated that LongS is an elite two-line male sterile with a good plant architechture, low critical sterility temperature, out-crossing superiority and broad spectrum blast resistance with a major dominant blast R gene Pi-LS(t). The identified linkage molecular markers of Pi-LS(t) are useful for futher gene cloning and marker-assisted rice blast resistance breeding.更多还原