Genetic Analysis And Molecular Marker On Chilling Tolerance Of Soybean In Early Stage

Soybean is an important source of human protein and oil, at the same time it is rigid susceptible to temperature and light. Low temperature susceptibility of soybean in early growth stage not only limits soybean's planting in high latitude area but also restricts common bean's spring sowing in South. In this study, the chilling-tolerated ability of soybean cultivars which coming from different ecological areas has been screened; and also the screening method has been perfected. According to the results of screening, a cross has been designed and the mixed one major gene plus polygenes inheritance model is used to analyse its genetic type; the segregating generation of the cross is used to mark the chilling tolerance gene. The results as following:1. The screening test and the screening method perfection of soybean chilling tolerance during early growth stageWe have screened the early stage's chilling tolerance of soybean. Among 102 cultivars coming from different ecological area, 13 show most tolerance and 49 show more tolerance. There are great differences on soybean chilling tolerance during early stage in cultivars. And there are differences in areas: the cultivars sowing in spring in north have better chilling tolerance than the cultivars sowing in summer, autumn or in the four seasons in south.According the analysis of cultivars chilling tolerance under different temperatures, there are lots of differences in cultivars and great correlation in results between experiment and plot with the time of cotyledon parallel at 10℃ as criterion. So we thought the time of cotyledon parallel at 10℃ could be used as the method in soybean chilling tolerance in early stage testing.2. Genetic analysis on the chilling tolerance of soybeanAccording to the screening experiment, the cross Zhou 9311-3 (chilling susceptive) × Xu9125(chilling tolerant) is designed and their descendants F1, F2 and F2:3 is obtained.Homogenity test of reciprocal crosses of Zhou 9311-3×Xu 9125 in F2 population indicates that there is no maternity inherence.Five populations from the cross of Zhou 9311-3and Xu 9125, P1.F1.P2. F2 and F2:3,were used to detect the inheritance of resistance to low temperature. The result indicated that the "one major gene plus polygene" mixed inheritance model suits the chilling tolerance and the major gene was overdominance.3. Molecular marker of soybean chilling tolerance during early stage600 SSR primer pairs chosen in random has used to detect the polymorphism between Zhou 9311-3 and Xu 9125, 219 SSR showed polymorphic DNA bands in parents and 11 showed polymorphic DNA bands between tolerant pool (TP) and susceptive pool (SP). Two markers (satt562, satt157), lain on two LGs (I, D1b), are found to link with these traits. The individual effect of each QTL was reported as R2 value. The effect was about 13.39% and 3.4%.