Analysis Of Quantitative Trait Locus For Stem Borer Resistance In Rice

On the base of difference in rice resistance level to the stripped stem borer (SSB) Chilo suppressalis (Walker) among 12 sets of rice genetic mapping systems, Doubled haploid (DH) IR62266-42-6-2 and CT9993-5-10-1-M is selected as rice material to investigate the traits of the dead sheath, dead heart and white head which the stem borer caused and also the rice morphologic and physical traits such as plant height, tiller numbers, leaf color, leaf angle, the density of silicon cells, then the major quantitative trait locus (QTLs) and epistatic QTLs are analyzed and also located using a genetic software to afford useful understanding to the genetic information of how the rice resists the stem borer. The results is underline:1. Comparison of the rice resistance level to stem borer in the parents of 12 sets of rice genetic mapping populationsIn two periods of rice growth, viz maximum tilling and reproductive stages, to measure the survival of SSB by infestation of the larvae to the rice plants, to compare the difference of resistant SSB level of the parents. The result showed: ffi.62266-42-6-2 and CT9993-5-10-1-M were significantly different in the resistant level for SSB, and this proved them to be potential as experimental material for identification of genes (QTLs) controlling stem borer resistant. There were some other rice genetic mapping groups, including COS 9 and IAC165, Zhenshan 97A and Minghui 63, Jingxi 17 andZhayeqing 8, Lemont and Teqing, IR64 and Azucena,IR20 and 63-83, Bala and Azucena, and so on, while the pair of Asominori and IR24 don't have such potential.2. Correlation analysis between partial rice morphological and physical traits and injury traits caused by the rice stem borersThe result showed plant height (PH) of rice in different periods have significant positive correlation to those of previous periods, and the correlation of tiller number (TL) are similar to PH. But there isn't significant positive correlation between PH and TL; Rice tiller number in various periods have significant negative correlation with the leaf color (LC) hi rice maximum tillering and reproductive stages. Tiller angle (TA) at rice maximum tillering and heading stages and the heading date (HD) have significant PH in each sampling period, and have significant negative correlation with TL in some periods of rice growth. The rice stem thickness (ST) and rice stem inner distance (ID) and rice vascular bundle distance (VD) have significant positive correlation with PH in some periods of rice, and have significant negative correlation with TL, so does the rice vascular bundle width (VW). VD and VW has significant negative correlation with HD respectively.The square root transformed percentage of dead sheath (QPDS) and square root transformed percentage of dead heart (QPDH) and square root transformed percentage of white head (QPWH) have significant positive correlation with square root transformed percentage of total damage by stem borer (QPD). There are significant correlation among QPDS, QPDH and QPWH. The degree of QPDS0616 has direct relations with the QPDH0630 and QPWH0714. There is significant positive correlation between QPDH0616 and QPDH0630. QPDH0728 and QPWH0814 have the same result, too. All above-mentioned show that both dead sheath (DS) and dead heart (DH) in early period are inherently related with the dead heart (DH) in later period. ThePH, TL, LC, TA, HD, ST, ID, VD of rice has significant correlation to the stem borer resistance trait in rice such as QPDS, QPDH and QPWH respectively. PH in same periods have significant positive correlation with QPDS, QPDH and QPWH, butTL in same periods has significant negative correlation with QPDS, QPDH and QPWH. Leaf color reading (LC2) and tiller angle (TA2) at reproductive stage have significant positive correlation with rice damage traits. HD has significant negative correlation with QPDS and QPWH. However, ST> ID and VD have significant positive correlation with rice damage trait at some periods.3. QTL analysis of stem borer injur...