回交高代选择导入系的纹枯病抗性与抗旱性的遗传重叠研究

利用来自抗旱性较好的供体亲本（BG300和BG304）、具有两种遗传背景（IR64和特青）的水稻高代回交（BC2）抗旱选择导入系，通过人工接种的方法鉴定纹枯病抗性，考察纹枯病抗性与抗旱性之间可能存在的遗传重叠。通过与受体亲本的纹枯病抗性表现比较发现，具有特青背景的抗旱选择导入系倾向于纹枯病抗性的降低，而IR64背景的抗旱选择导入系则倾向于纹枯病抗性的增强。基于基因型与表型的方差分析共鉴定到6个与纹枯病抗性相关的位点，其中QSbr6在不同供体和背景的两个群体中分别检测到，而QSbr10则在同一供体的两个遗传背景下均检测到；有3个位点（QSbr6、QSbr8和QSbr10）与同一群体中检测到的抗旱性位点位置相近，很可能是两种抗性重叠的遗传基础。尽管方差分析的方法在选择导入系的非选择目标性状相关位点的鉴定中存在相当程度的偏低估计，本研究所检测到的纹枯病抗性位点，特别是那些与抗旱性重叠位点的分子标记以及相关的抗性株系仍将为进一步的水稻纹枯病抗性和抗旱性的多抗性育种和深入的遗传重叠研究提供有用的信息和材料。

Preliminary Identification of Genetic Overlaps between Sheath Blight Resistance and Drought Tolerance in the Introgression Lines from Directional Selection

With the combination of advanced backcrossing and artificial directional selection for yield under drought stresses at rain-fed lowland and upland,sixty-five BC2 introgression lines(ILs)with two relatively uniformed genetic backgrounds(IR64 and Teqing)and two donors with relatively good drought tolerances(BG300 and BG304)were developed and assayed with SSR makers.Using this set of materials,SBR was identified by artificial inoculations of R.solani from fields at Philippines belonging to the AG-1 group.Lengths of all lesions(TLL)from 5 randomly selected tillers per hill were measured.Analysis of genetic overlap between SBR and DT was carried out at two levels.The first is the phenotypic analysis for SBR of the DT ILs from directional selection,in which the recurrent parents(RP)were used as the control and the ILs behaved better in yield were selected under the stress when the RP were almost killed and had not seed.The Teqing DT ILs tended to be decreased in SBR due to the selective introgression comparing with their RP,which showed medium resistance(MR)in our test;while the IR64 DT ILs tended to be increased in SBR comparing with IR64,which represented medium susceptibility(MS)in the same test.This kind of purge caused by directional selection indicated the possible correlation of DT with SBR in this set of ILs at the phenotypic level.The sencond is the genomic region overlaps detected by ANOVA and excessive introgression.Besides the underestimates by ANOVA of SBR loci,a total of six loci were found to be associated with SBR in DT ILs and five of them matched the 7 of the 26 loci reported previously by other researchers.Among the 6 loci,QSbr10 was detected for the same donor alleles in both backgrounds,while QSbr6 was detected for different donor alleles in different backgrounds;three loci(QSbr6,QSbr8,and QSbr10)overlaped the DT loci detected with the same ILs in our previous study.