水、旱稻根基粗和抗旱系数QTL的标记辅助选择及验证(英文)

Marker-Assisted Selection and Its Verification for QTLs of Basal Root Thickness and Index of Drought Resistance in Lowland Rice and Upland Rice

利用水、早稻杂交、回交所产生的4个分离群体对RIL群体定位到的抗旱相关的根基粗、抗旱系数2个QTL进行了选择验证。结果表明，根基粗、抗旱系数QTL的两侧标记在不同群体、不同的遗传背景中遗传稳定。在旱田种植条件下，YIBC1、JIBC1和JIF2 3个分离群体携带有根基粗QTL brt4．1两侧标记有利等位基因的个体与未携带brt4．1两侧标记有利等位基因的个体均值差为0．05～0．06mm，均达到显著或极显著水平，MAS效应为5．05％～6．12％；利用抗旱系数QTL idr6．1两侧标记进行选择时，入选个体的单株产量均值差为5．04～8．18g，均达到显著或极显著水平，MAS效应为34．89％～58．88％。用根基粗、抗旱系数2个QTL的两侧标记同时进行选择时，入选个体的根基粗、单株产量均值差分别为0．06～0．08mm、4．88～11．15g，同样达到显著或极显著水平，MAS效应分别高达6．06％～8．16％和39．91％～70．48％。旱田3个分离群体基于双标记、单标记选择结果表明，发生在brt4．1、idr6．1标记区间的单交换值分别为4．32％、10．27％，利用brt4．1、idr6．1单侧标记进行选择也获得了较好的选果。在水田种植条件下，YIBC1群体携带有根基粗、抗旱系数QTL两侧标记有利等位基因的个体与没有携带QTL有利等位基因的个体均值差异均不显著，表明brt4．1和idr6．1为旱田特异表达。4个分离群体的选择结果验证了QTL定位的真实性、可靠性。另外，还对QTL及其两侧标记的选择效应及水旱稻抗旱育种策略进行了探讨。

Accurate mapping of the target traits is prerequisite for effectiveness of marker-assisted selection （MAS）, Two previously identified quantitative trait loci （QTLs） conferring thicker basal root thickness （BRT） and higher index of drought resistance （IDR）, located on chromosomes 4 and 6, designated brt4.1 and idr6.1 respectively, were chosen as target QTLs to study the MAS effects for traits related to rice drought resistance. Four segregating populations derived from crosses between a drought resistance upland rice cultivar and two lowland rice cultivars with high yield potential and better grain quality were used in this study. The results showed that the flanking markers of brt4.1 and idr6.1 were genetically stable in different populations, with different genetic backgrounds. In the populations of YIBC1 , JIBC1 and JIF2 under upland condition, the differences between the means of the basal root thickness （BRT） of individuals carrying and not carrying favorable alleles of brt4.1 flanking markers were 0.05-0.06 mm, which was significant at 5% or 1% probability levels. The MAS effects were 5.05%-6.12%. When selection with flanking markers of idr6.1, the differences between the means of the upland grain yield per plant （YP） were 5.04-8.18 g, significant at 5% or 1% probability levels. The MAS effects were 34.89%-58.88%. For the flanking markers of both of these QTLs were selected simultaneously, the corresponding differences were 0.06-0.08 mm and 4.88-11.15 g, and the MAS effects were 6.06%-8.16% and 39.91%-70.48% respectively. The results also revealed that selection with flanking markers of brt4.1 or idr6.1 or both of them could not obtain the expected drought resistance in population YIBC1 under lowland conditions, The MAS effects based on selection for one or both of the flanking markers of the target QTLs were also studied. A working procedure for rice drought resistance breeding was suggested.