Study On The Genetic Diversity Of Winter Wheat Germplasm With Drought-resistance

Wheat is the first staple grain crops in the world. Arid is one of the major limiting factors for wheat production. Breeding new wheat variety with drought-resistance and water-saving is the best economical and effective way to fight drought. Wheat germplasm resources with drought-resistance are the material base for drought-resistant and water-saving variety breeding. Long-term directional selection results in high genetic similarity, lows genetic difference, and decreases genetic diversity as the population stabilizes on a particular trait value. Therefore, study on the genetic diversity of wheat genotypes with drought-resistance is very important for developing and using wheat germplasm resources with drought-resistance. 42 genotypes of winter wheat were used to study on genetic difference and diversity both in the levels of traits and the molecular to provide the theoretical base for drought-resistant and water-saving wheat germplasm resources use and parent selection. The main results of this research as below:1,There are obvious difference among the 42 different winter wheat genotypes in character. The result of the study by analysis of Shannon-weaver diversity index and UPGMA clustering indicates that the diversity indexes of canopy temperature in early and late grain filling stages, the number of spikelet, and grain yield are relatively high,showing there are many types of variation in these traits; the order of genetic distance (Squared Euclidean Distance) is overseas materials only>home materials only. Therefore, introduction of abroad winter wheat genotypes with drought-resistance extends the germplasm resources for breeding new winter wheat genotypes with drought-resistance and water-saving in character level.2,There are also great genetic variation among the 42 different winter wheat genotypes in molecular level of DNA. The result of study on genetic difference and diversity among these genotypes by RAPD with thirty-nine primers screened from 120 arbitrarily primers shows that RAPD is the relatively accurate, feasible molecular marker to study genetic difference and diversity of winter wheat germplasm resources with drought-resistance. A total of 378 bands are amplified and there are 165 polymorphic bands. The percentage of polymorphic bands is 43.65%. The change trend of genetic variation and diversity among the 42 genotypes is in the same respective order as it is in character level although the result of cluster analysis is partly same as it in character level. The trend of genetic distance: overseas genotypes>home genotypes. Introduction of overseas winter wheat genotypes with drought-resistance expands the winter wheat germplasm resources with drought-resistance and water-saving, enhances the genetic diversity of the germplasm resources in molecular level of DNA.3,Plant character is controlled by gene and influenced by environment. It is the result of the genotypes'adaptation to environment. The result of cluster analysis by unweighted pair group method using arithmetic average of DPS3.0, based on Euclidean Distance with morphological marker is partly same as it by unweighted pair group method using arithmetic average of Popgene32, based on genetic distance with RAPD, but the trend of variation of genotypes with morphological marker is consistent. The variation of genotypes with morphological marker fails to show all real genetic variation of genotypes in DNA , but it can show the variation trend in DNA to some extent.4,There are specific bands amplified by primer S32, S156 and S1126 in the genotype R2. Specific bands are also found in other three genotypes, 9840-0-3-3-1-3, 0052-17-2 and R40. These specific bands show four genotypes'specific in DNA. It is necessary to carry out further research on these specific bands. If it is possible, these primers can be used as the molecular markers for specific characters of these genotypes.