Development Of EST Marker In Wheat And Their Applications

The increasing availability of expressed sequence tags (ESTs) provides an invaluableresource of EST markers. The ESTs encoding transcription used in this study included 161ESTs with SSR downloaded from/TEC (International Triteace EST Cooperation) and 237ESTs from cDNA libraries of Sumai No.3 spikes inoculated by F. graminearumdownloaded from NCBI server, 357 EST-STS primers were designed. The primersincluding 161 EST-SSR and 357 EST-STS were then surveyed for polymorphism betweenNanda2419 and Wangshuibai. Fifty-six loci resulted from 56 polymorphic markers wereadded to the genetic map of recombinant inbred line (RIL) population ofNanda2419xWangshuibai constructed by Lin et al. (2004). 161 EST-SSR primers were alsosurveyed for polymorphism between Opata and W7984, the parent of ITMI population.Twenty-one polymorphic EST-SSR markers were identified and were mapped on thispopulation.By using the number of diseased spikelets (NDS) and the length of disease rachides(LDR) as the typeâ…¡resistance index, twelve EST markers showing association with typeâ…¡resistance were identified in the Nanda2419xWangshuibai population through one-wayANOVA analysis, four of which were mapped to the QTL region on chromosome 6Breported by Lin et al. (2004), and three of which were mapped nearby the QTL regions onchromosome 6B and 3B. Six EST markers showing association with typeâ… resistance wereidentified using the percentage of infected spikes (PIS) as the typeâ… resistance index. Twoof them were mapped to the QTL region on chromosome 2D reported by Lin et al. (2006),one was mapped nearby the QTL region on chromosome 4B.Eleven of the EST markers associated with FHB resistance were selected forexpression analysis by using cDNA from spikes of resistant cultivar 'Wangshuibai' andsusceptible cultivar 'Nanda2419' harvested 0h, 6h, 12h, 24h, and 48h after inoculation withF. graminearum. The results showed that all but MAG2053 were induced by F.graminearum infection. Four ESTs showed the same expression pattern between theresistant and susceptible cultivars, and six showed differentia expression patterns betweenthem.In addition, nine genomic SSR markers were developed and mapped using C. S.nulli-tetrasomic lines and the RIL population of Nanda2419xWangshuibai.In order to identify and exploit beneficial genes in einkorn wheat, 35 einkorn wheataccessions, three tetrploid wheat lines and one common wheat were characterized for theirgenetic diversity using 33 EST-SSR markers and 41 genome DNA derived SSR markersthat located on the A genome of common wheat. The result showed that, a total of 33primers detected polymorphism among the 35 einkorn accessions, and 211 alleles weredetected with an average of 6.03 alleles per locus. UPGMA analysis suggested that 35einkorn accessions could be classified into seven groups using genetic distance of 0.5 as the threshold. The clusters displayed considerable correspondence to powdery mildewresistance of the lines, and the genetic distance between the einkorn and emmer wheat linesimplied that A genome of emmer lines have multiple origins.