东乡野生稻耐冷渐渗系的细胞学观察及SSR分析

以前期鉴定筛选的2个东乡野生稻强耐冷渐渗系(IL5243和IL5335)为试材,研究其减数分裂时期的染色体行为特征及外源基因的渗入分子证据。结果表明:(1)IL5243和IL5335中正常减数分裂的花粉母细胞分别达89.93%和90.22%,最终形成正常的成熟花粉粒,花粉离体萌发率分别为(83.03±2.82)%和(81.96±1.73)%,与受体亲本无显著性差异。(2)在减数分裂I中,2个耐冷渐渗系均观察到低频率异常染色体行为,如单价体、"8"字型二价体、多价体,以及后期I有少数花粉母细胞(3.95%～5.15%)存在落后染色体等,表明其染色体组之间发生了交换和重组;在粗线期,2个强耐冷渐渗系均观察到较高频率(IL5243和IL5335分别为27.0%和38.9%)的双核仁,而其双亲都是单核仁。(3)SSR标记和Structure分析进一步证实了栽培稻和野生稻染色体组间发生了交换重组,东乡野生稻部分DNA片段已渗入到强耐冷渐渗系中,这为水稻耐冷基因的挖掘与利用奠定了重要基础。

Cytological and SSR Analysis on Cold tolerant Gene Introgression Lines from Dongxiang Wild Rice

Two previously identified strong cold-tolerant introgression lines of IL5243 and IL5335 from Dongxiang wild rice(Oryza rufipogon Griff.) were used to investigate the meiosis behavior,chromosome recombination and the molecular evidence of alien genes introgression.The results showed that the rate of pollen mother cells(PMC) with normal meiotic behavior in the IL5243 and IL5335 was to 89.93% and 90.22%,respectively.And they finally formed the normal mature pollen;The rates of pollen germination in vitro were(83.03±2.82)% and(81.96±1.73)%,respectively.There were no significant differences between the cold-tolerant introgression lines and their parents.However,at meiosis I,the low frequency of abnormal chromosome behavior was observed in IL5243 and IL5335,such as univalent,8-shape bivalent,multivalent and some PMCs(3.95%-5.15%) exist lagging chromosomes at anaphase I and so on,which suggested that there were genetic exchange and recombination between cultivated rice and common wild rice.In addition,the high frequency of double nucleoli was observed at pachytene in the two cold tolerance introgression lines(IL5335 and IL5243 were 38.9% and 27.0%,respectively),while their parents only had one nucleolus.Through SSR markers and structure analysis,we further confirmed that introgression of some Dongxiang wild rice DNA fragments in the strong cold resistance introgression lines through chromosome exchange and recombination between the cultivated rice and the wild rice.These results laid a foundation for further excavating and using this rice cold-tolerant gene in the future.