Development of T. aestivum L.eH. californicum Alien Chromosome Lines and Assignment of Homoeologous Groups of Hordeum californicum Chromosomes

Hordeum californicum （2n = 2x = 14, HH） is resistant to several wheat diseases and tolerant to lower nitrogen. In this study, a molecular karyotype of H. californicum chromosomes in the Triticum aestivum L. cv. Chinese Spring （CS）-H. californicum amphidiploid （2n = 6x = 56, AABBDDHH） was established. By genomic in situ hybridization （GISH） and multicolor fluorescent in situ hybridization （FISH） using repetitive DNA clones （pTa71, pTa794 and pSc119.2） as probes, the H. californicum chromosomes could be differentiated from each other and from the wheat chromosomes unequivocally. Based on molecular karyotype and marker analyses, 12 wheat--alien chromosome lines, including four disomic addition lines （DAH1, DAH3, DAH5 and DAH6）, five telosomic addition lines （MtH7L, MtHIS, MtH1L, DtH6S and DtH6L）, one multiple addition line involving H. californicum chromosome H2, one disomic substitution line （DSH4） and one translocation line （TH7S/1BL）, were identified from the progenies derived from the crosses of CS-H. californicum amphidiploid with common wheat varieties. A total of 482 EST （expressed sequence tag） or SSR （simple sequence repeat） markers specific for individual H. californicum chromosomes were identified, and 47, 50, 45, 49, 21, 51 and 40 markers were assigned to chromosomes H1, H2, H3, H4, H5, H6 and H7, respectively. According to the chromosome allocation of these markers, chromosomes H2, H3, H4, H5, and H7 of H. californicum have relationship with wheat homoeologous groups 5, 2, 6, 3, and 1, and hence could be designated as 5Hc, 2He, 6Hc, 3Hc and 1Hc, respectively. The chromosomes H1 and H6 were designated as 7Hc and 4Hc, respectively, by referring to SSR markers located on rye chromosomes.

Characterization of T.aestivum-H.californicum chromosome addition lines DA2H and MA5H

In order to transfer useful genes of Hordeum californicum into common wheat （Triticum aestivum L.）, the T. aestivum c.v. Chinese Spring （CS）-H. californicum amphiploid was crossed to CS, and its backcrossing and self-fertilized progenies were analyzed by morpho- logical observation, cytological, biochemical and molecular marker techniques. Alien addition lines with two H. californicum chromo- somes were identified and their genetic constitution was characterized. STS-PCR analysis using chromosome 2B specific markers indi- cated that chromosome H3 of H. californicum belongs to homoeologous group 2, and was thus designated 2H. SDS-PAGE showed that chromosome H2 of H. californicum belongs to homoeologous group 5, and was designated 5H. The CS-H. californicum amphiploid and the chromosome addition lines （DA2H and MA5H） identified were evaluated for powdery mildew （Erysiphe graminis f. sp. triticii） resis- tance in field. The preliminary results indicated that the amphiploid showed higher powdery mildew resistance than CS. However, chro- mosome addition lines DA2H and MA5H were highly susceptible to powdery mildew, indicating that major powdery mildew resistant genes of H. californicum should be located on chromosomes other than 2H and 5H.

加州野大麦染色体C-分带、荧光原位杂交及其核型分析

以二倍体加州野大麦(Hordeum californicum)及普通小麦中国春(Chinese spring,CS)-加州野大麦的双二倍体为材料,进行依次染色体C-分带和荧光原位杂交(FISH)分析。结果表明:小麦背景中的加州野大麦染色体都显示较强的末端带,7对染色体之间带的数目和强弱均存在明显差异,可以和普通小麦染色体相互区分开来;以45srDNA为探针进行荧光原位杂交发现,二倍体和双二倍体中加州野大麦的NOR位点均位于第7对染色体短臂上;基于根尖细胞有丝分裂中期染色体C-分带和原位杂交结果,利用Motic images plus 2.0 ML软件“数码显微图像处理系统”进行核型分析,确定加州野大麦的核型为2n=2x=10 m(2SAT)+4 sm,属于较为对称性核型(A);加州野大麦染色体核型的建立,为利用远缘杂交和染色体工程转移加州野大麦的有利基因奠定了基础。

利用PCR技术初步鉴定小麦加州野大麦异染色体系

为快速鉴定普通小麦与普通小麦加州野大麦双二倍体杂交、回交后代植株的染色体组成 ,研究小麦背景中添加的外源染色体与小麦染色体之间的部分同源关系 ,选用已被定位在小麦 7个部分同源群 2 1条染色体上的 38个SSR引物对杂种回交后代植株进行PCR扩增。结果表明 ,其中 2 7个小麦SSR引物在普通小麦与小麦加州野大麦双二倍体间有多态性扩增 ,涉及 4个部分同源群的 11对引物 ,可在不同杂种回交植株中扩增出与双二倍体相同的多态带纹 ;根据PCR扩增和细胞遗传学分析的结果 ,在 18个回交后代中初步鉴定出 7个可能的异附加系 ,其中 2个二体异附加系、 1个端二体异附加系、 2个单体异附加系和 2个双单体异附加系。所选育的异附加系分别涉及第 1、 2、 4和 7部分同源群。