小麦细胞分裂间期外源染色质的检测

Detection of Alien Chromatins Introgressed into Wheat in Mitotic Interphase

以野生种基因组DNA为探针，用荧光原位杂交研究了间期细胞核里黑麦、中间偃麦草、燕麦和簇毛麦染色体在普通小麦背景下的行为。易位的黑麦1RS染色体臂在间期表现为不连续的线状杂交信号贯穿细胞核，代换和附加的1R染色体在间期却呈现点状杂交信号，通过易位进人小麦的中间偃麦草和燕麦染色体片段也是点状。普通小麦与硬粒小麦－簇毛麦双二倍体杂种F1幼胚愈伤组织细胞中，7个簇毛麦染色体在不同间期核里表现为由点状到线状接近连续的趋势，簇毛麦染色质与小麦染色质不相融合。对于附加、代换和易位等方式进入小麦里的少数染色体或染色体片段可以在问期中准确地计数，但是对于较多的外源染色体，由于有些杂交信号有可能被小麦染色质遮盖，所以仅仅分析间期细胞可能是不准确的。黑麦和簇毛麦随体染色体1R和1V不与核仁相连，它们在小麦背景下对核仁形成的作用可能被抑制了。

Fluorescent in situ hybridization of biotin labelled total genomic DNA from alien species as probes was applied to illustrate chromatin behaviors of Secale cereale L,Thinopyrum intermedium Host., Avana fatua L, and Dasypyrum villosum (L.) Candagy introgressed into wheat (Triticum aestivum L.) in interphase cells. A pair of 1RS chromosome arms in IBL/ IRS translocations were visible as discrete domains traversing through the interphase nucleolus. The substitution and addition 1R chromosomes as well as the translocared chromosome segments of Th. intermedium and A. Avena appeared as bright spots in interphase. In callli derived from immature embryos of a hybrid betWeen T durum-D. villosum amphidiploid and T aestivum, seven D.villosum originated chromatins presented nearly consecutive trend from spots to domains. Chromatins from both parents did not tend to mix with each other at interphase of the hybrid calli. It is feasible to count the number of alien chromosomes and chromosome segments in the case of addition, substitution and/or traslocation at interphase. As far as more alien chromosomes are considered, it seems not reliable to analyze the interphase nucleolus alone because some of the signals might be overlapped by chromatins of wheat. Neither S cereale satellited chromosome 1R nor D. villosum tV chromosome involving within the envelop of interphase nucleolus were associated with nucleon, suggesting that their functions in the formation of nucleoli are inhibited in the wheat background.