Seedling Chestnut (of Castanea Mollissima Bl.) Population Genetic Diversity And Its Effect On Millet Phytophthora Resistance

Study on the Genetic Diversity of Natural Chestnut(Catanea mollissima Bl.)Population of China and the resistance to Cryphonectria parasiticaPostgraduate: Liu debing Tutor: Prof Fan chonghui; Prof Qin ling(College of Horticulture,Northwest Sci-tech University of Agricultura and Forestry ,Yangling,Shaanxi,712100)China chestnut has an important status in Castanea Miller plant and a dominant function on chestnut conservation in the world.It is an important resource of breeding about resistance to disease and pest.It is also a mainly genetic source on improvement of edible chestnut in the world.Its abundant genetic resource had been formed by long-term seedling propagation and diversity of complicated ecological-geographical condition in natural distributing region. China chestnut populations had abundant genetic diversities.Genetic variability of 6 national chestnut populations in North-Western China and North China was investigated using isoelectric focusing in thin-layer polyarcylamide slab gels at 20 loci coding for 8 enzyme systems. The result showed that the genetic diversity of North-Western China was higher than that of North China. Comparison of the population genetic variability of Castanea mollissima in two main commercial planting regions of China, the populations from North-Western China showed a markedly higher mean expected heterozygosity.The percentage of polymorphic loci (P) were 77.5% and 75.0%, and the expected heterozygosity(He) were 0.321 and 0.307 respectively. Genetic differentiation between populations in North China and North-Western China were 4.5% and 6.2%.The total average diversity was 0.335, about 95.47% of genetic variation was attributed within populations, while the remaining 4.53% among populations. Among North-Western China regions, the southern of Qinling and the northern of Qinling can be seemed as two divided region.Genetic relationships among populations was assessed by Nei genetic indentity (I) and standard genetic distance (D), suggesting that North China populations and northern of Qinling populations have closer relationship.The study provided useful information for understanding of the genetic resources and evolutionary events in natural chestnut and for planning an effective conservation strategy. At the same time ,we studied the genetic diversity of Castanea mollissima population in North-Western China and North China and the hereditial difference of regions.The main purpose of researching genetic diversity,genetic distance and potential status of Castanea mollissima population in North-Western China and North China in chestnut systerm evolution were to futher realize hereditial source of Castanea mollissima in our country and to provide theorical proof for reasonally utilize and converse chestnut resources. We analysised living condition of Cryphonectria paristtics.Genetic variability of two national chestnut populations of diseasedness and non-diseasedness were investigated using isoelectric focusing in thin-layer polyarcylamide slab gels.The result showed that the allete mean (A) of two populations were equal.The percentage of loci polymorphic(P),direct count mean heterozygosity(Ho), hdyWbg expected mean heterozygosity(He)of the former were all higher than the latter.The degree of genetic differentiation(F) of diseasedness population were high and both means of them were negative (ie: -0.216 , -0.241)The seedlings and graftings "Huai huang"of chestnut were selected as experimental materials. The sticks exposed to the attack of the block of Cryphonectric parasitica isolates(FB), CFE and ME respectively .The activity and specific activity of chitinase and β-1,3-Glucanase were measured every eight hours later. The results showed that the block of Cryphonectric parasitica(FB) had the highest induced effect on activity and specific activity of the two enzymes. The activities of chitinase andβ-1,3-Glucanase were gradually increased and reached the top in 30-40hours. The activities of the two enzymes of seedlings were higher than that of t...