水稻苗期耐淹相关性状QTL分析

QTL Analysis of Traits Concerned Submergence Tolerance at Seedling Stage in Rice (Oryza sativa L.)

以相同淹水条件下存活率差异较大的籼稻TN1与粳稻春江06（CJ06）为亲本构建的DH群体为试材，考察了DH群体及其双亲与苗期耐淹相关的5个性状，各性状均表现为连续分布，且都存在一定数量的双向超亲遗传类型，受多基因控制。使用分子连锁图谱进行QTL分析，共检测到16个与苗期耐淹有关的QTL，包括4个中胚轴长度QTL、3个株高QTL、3个存活率QTL、3个干重相对受害率QTL和3个叶绿素受损指数QTL，分别位于第1、2、3、4、6、8、9和12染色体。所有QTL的LOD值介于2．26～4．64；存活率qL-4、qL-8和qL-9的LOD值分别为3．10、3．02和3．78，对表型变异的贡献率分别为17．2％、14．3％和41．1％。在第一染色体上的RM3412～RM6716区间同时检测到控制株高和干重相对受害率的QTL，说明株高与干重相对受害率在水稻苗期淹水条件下存在密切的遗传关系。揭示水稻的耐淹特性是一个多基因控制的复杂性状。

Flash flooding is one of the most severe natural disasters in the world. Submergence of rice seedling is a common problem for rice farmers. It severely reduces grain yield and increases the unpredictability of cropping. In generally, submergence tolerance is defined as the ability of a rice plant to surviving and continue growing after being completely submerged in water for several days. Rice plants are less tolerant of submergence at the early growth stages. Submergence tolerance is controlled by multi-genes with major effects, and minor modifiers. Therefore, it is important to find molecular markers associated with submergence tolerant, and be used in rice breeding by marker-assisted selection（MAS）. QTLs for 5 traits related to submergence tolerance, including length of mesocotyl （LM）, plant height （PH）, livability （L）, damage index of chlorophyll （DIOC） and relative damage percent of dry weight（RDP）, were investigated using a population of DH lines derived from a cross between TN1 and CJ06, which have different tolerances to submergence. Transgressive segregations for the 5 traits were observed in the population, and their frequencies were approximately normal distributions. Generally, 16 QTLs for submergence tolerance at seedling stage in rice were detected on chromosomes 1, 2, 3, 4, 6, 8, 9, 11 and 12, including 4 QTLs for LOE, 3 QTLs for PH, 3 QTLs for L, 3 QTLs for DIOC and 3 QTLs for RDP, respectively. LODs of the QTLs related to submergence tolerance at seedling stage in rice varied from 2.26 to 4.64. Three QTLs （qL-4, qL-8 and qL-9） for livability were detected on chromosomes 4, 8 and 9,their LOD values were 3.10, 3.02 and 3.78, and their contributions were 17.2 %, 14.3 % and 41.1%, respectively. The regions of RM3412- RM6716 was detected simultaneously for affecting plant height and relative damage percent of dry weight. It is indicated that there is close genetic correlation between plant height and relative damage percent of dry weight under submergence tolerance at seedling stage in rice, suggesting that the trait of submergence is controlled by many genes in rice. These finding establish the foundations of marker-assisted selection and gene cloning of submergence tolerance of rice.