Molecular population genetics of wild ancestral species of wheat

用一组4-切酶对Sitopsis组的5种二倍体山羊草和2种野生四倍体小麦T.dicoccoides和T.araraticum的两个5-6kb的叶绿体DNA区域进行了限制性内切酶图谱的变异研究。共获得250多个限制性内切酶切点，其中只有7个切点在斯卑尔托伊蚊中是多态的。在所有其他二倍体和四倍体物种中均未检测到限制性内切酶切点的多态性。此外，还检测到6个插入/缺失多态，但它们是独特的或物种特有的。估计的核苷酸多样性(pi：Nei和Li，1979年)为0.0006，而所有其他调查物种为0.0000。在Ae.speltoides中，Tajima‘s D(1989)没有显著差异，表明没有明显偏离DNA多态的中立性。在斯卑尔托伊蚊多态酶切位点之间的10个可能的组合中，有3个组合检测到显著的非随机关联。各质型间的系统发育关系表明，二粒盾叶蜂和阿拉蒂盾叶蜂的系统发育关系较好。1个Ae.speltoides加入的质粒型与主要类型的araraticum(包括T.timopheevi)相同。在Sitopsis种中发现的三种质型与T.dicoccoides、T.hard um和T.aestivum非常相似，但不完全相同。利用随机核DNA克隆技术研究了山羊草组5种山羊草属植物的限制性片段长度多态性。斯卑尔托伊蚊的多态程度与其他4个种的种间差异程度相当。该RFLP分析得到的系统发育关系与经典的基于叶绿体DNA形态分类和RFLP分析的系统发育关系一致。

Restriction map variation in two 5-6 kb chloroplast DNA regions of five diploid Aegilops species in the section Sitopsis and two wild tetraploid wheats, T.dicoccoides and T.araraticum was investigated with a battery of 4-cutter restriction enzymes. More than 250 restriction sites were scored, of which only seven sites were polymorphic in Ae.speltoides. No restriction site polymorphisms were detected in all the other diploid and tetraploid species. In addition, six insertion/deletion polymorphisms were detected, but they were unique or species-specific. Estimated nucleotide diversity (pi : Nei and Li, 1979) was 0.0006 for Ae.speltoides, and 0.0000 for all the other investigated species. In Ae.speltoides, none of Tajima's D (1989) were significant, indicating no clear deviation from the neutrality of DNA polymorphisms. Significant non-random association was detected for three combinations out of ten possible pairs between polymorphic restriction sites in Ae.speltoides. Phylogenetic relationship among all the plastotypes (Plastid genotype) suggested the diphyletic origin of T.dicoccoides and T.araraticum. A plastotype of one Ae.speltoides accession was identical to the major type of T.araraticum (T.timopheevi inclusively) . Three of the plastotypes found in the Sitopsis species are very similar, but not identical, to that of T.dicoccoides, T.durum and T.aestivum. Restriction fragment length polymorphisms in the five Aegilops species of Sitopsis section were investigated by using random nuclear DNA clones. Level of polymorphism in Ae.speltoides is as high as that of interspecific divergence between the other four species. Phylogenetic relationship obtained by this RFLP analysis agrees with with those of classical taxonomy based on morphology and RFLP analysis on chloroplast DNA.