【作者】 唐九友；

【导师】 翟虎渠；

【作者基本信息】 南京农业大学 ， 作物遗传育种， 2004， 硕士

【摘要】 水稻种子休眠性是一个重要的农艺性状，培育适度休眠性的优良品种，对水稻生产尤为重要。本研究利用一个重组自交系群体在全基因组范围内对水稻种子休眠性QTL进行了检测，并进一步分析了各QTL对干热破除休眠处理的响应，以期找到效应值高且易于被干热处理解除的休眠性QTL，为利用分子标记辅助选择（marker-assisted selection，MAS）培育适宜休眠性的优良品种提供理论依据。同时本研究对水稻品种N22的种子休眠性进行了QTL分析，考虑到QTL的检测受环境及G×E互作的影响，以N22为亲本之一分别构建了三个分离群体，并基于SSR标记构建的三套连锁图谱进行了QTL比较定位。结果如下： 1、水稻种子休眠性QTL定位及其对干热处理的响应 利用Kinmaze（粳稻）／DV85（籼稻）杂交组合衍生的重组自交F₁₁家系（Recombinant Inbred Lines，RILs）进行了种子休眠性QTL的检测和遗传效应分析。以抽穗后35d的种子发芽率作为休眠性的表型值，分析亲本和81个家系的休眠性表现，采用区间作图法，在全基因组范围内共检测到4个种子休眠性QTL，分别位于第2、5、11染色体上，其中第2染色体存在2个QTL，各QTL的贡献率介于8.37％-17.40％之间。进一步研究了这些休眠性基因位点对干热破除休眠处理的响应，结果表明，来自DV85增强休眠性的QTL位点qDOR-2-1和qDOR-5，以及来自Kinmaze增强休眠性的QTL位点qDOR-11，易被干热处理破除休眠，这3个QTL效应较强，可在种子休眠性状的遗传改良中加以利用；而位于第2染色体上标记XNpb227-XNpb132之间的QTL位点qDOR-2-2却不易被干热处理破除休眠，该位点增强休眠性的基因来自DV85。 2、利用水稻品种N22组建的三个分离群体定位种子休眠性QTL 籼型水稻品种N22具有极强的种子休眠性，遗传学分析表明该品种的休眠性由1或2个主效基因控制，同时受到一些修饰基因的调节，但有关这些基因的染色体定位未见报道。本研究利用SSR标记，基于两个BC₁F₁群体：南粳35／N22／／南粳35、USSR5／N22／／USSR5，和一个F₂群体：USSR5／N22构建了三套遗传图谱，进而对水稻种子休眠性进行了QTL定位分析。结果在1、3、5、7及11染色体上共检测到5个学位论文水稻种子休眠性数量性状基因座的定位与分析主效休眠性QTL，分别命名为qs为乞一了、qsdNj一3、q.，力2一J、q&办2一7、qs力i一I了。除qs动Vj一了外，其他四个来自N22的QTL位点增强种子休眠性。qsdn一I在三个群体中同时检测到，且效应值相对较高，表达较为稳定，可望用于杭穗发芽品种的标记辅助选择（marker一assisted Seleetion，MAs）分子育种中。位点叮s动1一万和叮吕办2一11分别在不同的两个群体检测到，且其效应因环境及遗传组成的改变而差异显著;而qsdNj一了和qsd)，一7仅在一个群体中检测到，这两个位点的表达具有组合特异性。同时基于F:群体定位的结果对QTL的显性效应进行了估计，表明N22种子休眠性基因为不完全显性。关键词水稻;种子休眠性;数量性状基因座;干热处理;基因定位更多还原

【Abstract】 Seed dormancy in rice is an important agronomic trait as it relates to pre-harvest sprouting. Therefore, breeding for an intermediate level of dormancy in rice is highly desirable. In the present study, QTL for seed dormancy in rice was detected spanning the whole rice genome using a RI population. And response of each locus to a dormancy-breaking treatment with dry heat was further detected with the aim to identify such QTL that expressed with adequate effect to prevent sprouting in the field and that could be broken easily/quickly after harvest. We have also identified QTL for the strongest seed dormancy in rice cultivar N22. Consider the fact that the ability to detect genetic loci accounting for phenotypic variation of seed dormancy trait is compromised by the effects of environment and genotype environment interactions, we took a comparative QTL mapping using three temporary populations . The results were as follow:1. Analysis of QTL for seed dormancy and their response to dry heat treatment in rice.QTL controlling seed dormancy in rice was identified using recombinant inbred lines (RILs) population derived from the cross between a japonica variety Kinmaze and an indica variety DV85. Seeds of two parental cultivars and each RIL were harvested in 35d after heading. The germination percentage of these seeds at 30 C for 7 days were measured as the degree of seed dormancy. QTL analysis was performed using Windows QTL Cartographer 1.13a based on composite interval mapping. A total of four QTL for seed dormancy were detected on chromosome 2 (two regions), 5 and 11, respectively. Phenotypic variation explained by each QTL ranged from 8.37% to 17.40%. Responses of such loci to a dormancy-breaking treatment with dry heat were further detected. The results showed that two alleles of qDOR-2-1 and qDOR-5 from DV85 as well as the allele of qDOR-11 from Kinmaze increased the seed dormancy, which seemed to be easily broken by dry heat treatment. Such loci of seed dormancy may be applied to rice genetic improvement. The allele of qDOR-2-2 from DV85 increased the seed dormancy, which could not be broken easily by dry heat treatment.2. Comparative mapping of QTL for seed dormancy in rice cultivar: N22 among three populations.Among the rice cultivars, N22, an indica-type traditional cultivar, displayed the strongest seed dormancy. Based on conventional genetic analysis, a mono - and digenic model for seed dormancy in N22 were proposed respectively. But the chromosome locations of those genes have not been determined. For this analysis, three SSR (simple sequence repeats) linkage maps based on two BC1-type populations: Nanjing 35 (ajaponica breeding line with nondormant) /N22//NanJing 35 and USSR5 (nondormant japonica cultivar) /N22/USSR5, and a F2 population of a hybrid USSR5/N22, were constructed to detect the loci controlling seed dormancy. Five QTL for seed dormancy, qSdn-1, qSdNj-3, qSdn-5, qSdn-7 and qSdn-11, were identified on chromosome 1, 3, 5, 7 and 11, respectively. The N22 alleles increased seed dormancy, expect for qSdNj-3 on chromosome 3. The QTL qSdn-1 was detected with all the three populations, which indicated the stability of this QTL and its potential usefulness for improving rice pre-harvest sprouting tolerance using marker-assisted selection (MAS). Two QTL qSdn-5 and qSdn-11 were identified with differential two populations, separately, expression of their effect were varied significantly with the change of genetic and environment factors. And the remained two QTL, qSdNj-3 and qSdn-7, were only detected with one population at the same time. On the basis of the results from the F2 population, we confirmed that gene control seed dormancy in N22 is an incompletely dominant.更多还原