| Melia azedarach is one of the wild autochthonous trees with fast growing and multifunctional and comprehensive utilization such as lower toxic, higher efficient, broad-spectrum botanical pesticides. Most of the resources are continuously stellate distributed, however, some of the resources had been damaged badly. It is urgent to collection, conservation and evaluation of genetic diversity of M. azedarach for scientifical and rational protection for Germplasm resources, genetic improvement and the screening of superior germplasms ,which are the foundation of large-scale and industrialized biopesticide exploitation. Based on field investigations of the natural distribution and phonological diversity alloc-ation of M. azedarach , adopted multitudinous conservation model of scattered trees, 24 populations 729 individuals were sampled. Research on morphological diversity (24 populations 729 individuals) ;DNA diversity (8 populations 240 individuals,30 individuals in each population); the progeny seedling traits'diversity ;construction of core germplasm and germplasm resources conservation; coupling by morphological ,DNA diversity (AFLP ) and seedling traits'diversity had been made to find out genetic variation and genetic differentiation in M. azedarach. Some suggestions of protection for genetic diversity of M. azedarach at our best has been put forward.The main research results were as follows: 1 Based on the phenological data of 8 years (1994-2002) of M. azedarach in 70 meteorologic observation plots ,the principal component and cluster analysis have been made. 11 phenological diversity regions were founded in M. azedarach distributed area in China. It provided a science foundation for seedling optical allocation, germplasm resources conversation; and the phonological contour maps were a guidline for agriculture and forestry production in the most part of our southern country. 2 Research on morphological diverity of M. azedarach (1) The CV of six groups of phenotypical traits , which were leaf,fruit,seed number of fruit,drupe,seed,weight of per thousand were 24.59%,13.24%,16.82%,11.52%,11.5%,26.96%,respectively ,average 15.95%;the average of CV among populations is 14.01%; the average repeatability of 12 phenotypical traits was 0.50; the phenotypical differentiation coefficient (Vst) among populations(54.47%) was slightly greater than that of within populations(45.53%). (2) Based on the 5 geography-climate factors and 18 phenotypical characteristics data of 729 trees of 24 populations of M. azedarach in China distributed area , canonical correlation analysis(CCA)was applied for. The eigenvalue of the first canonical variable was 0.9979 (significantily at 0.01 level), accounting for 78% of all eigenvalue, and then further principle component analysis(PCA) was done, taking the first canonical variable coordinate values as phenotypical characteristics gradient axes, namely PCGA.It showed the geographical model of northeast-southwest variation trends of phenotypical characteristics of M. azedarach .Meanwhile ,the path analysis results showed that the direct and indirect effects of phenotypical characteristics with phenotypical characteristics gradient values, which proved the fact that the propagative organs are changing with steady steps. (3) Based on the 18 phenotypical characteristics data of 729 trees of 24 populations of M. azedarach in China distributed area ,the principal component and cluster analysis have been made. 5 phenotypical districts and 10 sub-phenotypical districts were founded . Canonical discriminant analysis showed significant differentiation among phenotypical distrits, but not for within phenotypical distrites .In order to interprete whether the 5 phenotypical districts were reasonable, canonical discriminant analysis has proved 93.8% historical data correct. The phenotypical allocation of M. azedarach provides a science foundation for germplasm resources conservation, reasonable sampling ,diversity assessment and a guidline for seedling optical allocation. 3 Research on DNA diverity (AFLP ) of M. azedarach The eight populations were further selected by the phenotypical allocation of M. azedarach,totally 240 individuals were selected and analyzed by amplifications using 7 pairs of AFLP primers pair, 650 polymorphic locus were obtained and 13 in a class by oneself were discovered. As for genetic diversity parameter,the percentage of polymorphic loci(P) ranging from 51.4%~76.29%(species level 98.78%); the number of alleles(A) ranging from 1.5410~1.7629 (species level 1.9878);the effective number of alleles(Ae) ranging from 1.1724~1.3231 (species level 1.3247); Shannon's information index(I) ranging from 0.1790~0.3077 (species level 0.3322); gene diversity index (H) ranging from 0.1101~0.1969 (species level 0.2060); genetic differentiation coefficient among populations (Gst) ranging from 0.1130~0.3053 (species level 20.43%); the percentage of variance components among populations were 27.3%; the gene flow (Nm ) ranging from 1.1378~3.9226 (species level 1.9477); average genetic identities was 0.946 ; average genetic distance was0.05632.According to the UPGMA cluster analysis , the 8 populations could divided obviously into six groups (SM=0.97) based on genetic identity. 4 Research on the progeny seedling traits'diversity in M. azedarach The seedling traits diversity was rich in M. azedarach.The CV of seedling traits were 18.74%, phenotypical differentiation coefficient showed that the variation within populations (55.45%) was higher than that of among populations(44.55%); the heritabilities of the seedling height and the caliper were 0.722 ,0.617 for family and 0.52, 0.36 for individual respectively; the genetic correlation coefficient of seedling height and caliper was 0.751; the growth patterns of height was fitted for "S"curve, it was significant in a way among /within populations with "t"test. 5 Research on coupling of genetic diversity in M. azedarach The coupling effects were better in experimental sampling, genetic diversity parameters, genetic diversity gradient variation, genetic diversity distribution, sampling strategy etc. With research on phonological diversity, morphological diversity, DNA diverity (AFLP ) and the progeny seedling traits'diversity in M. azedarach.The abundance of variation were in northwestward to southeastward, that's the south of Gansu province,Weinan of Shanxi province to Fujian province,Xiangtan of Hunan province. 6 The construction of core germplasm and germplasm conservation The sampling strategy for populations and individuals of core germplasm in M. azedarach was constructed ,which includes that the best method of conserving "8+1"populations (at least 1 population in each phenotypical districts ), sampling 28 individuals for each population; based on the construction of core germplasm, Ex situ conservation progeny testing stand at multiple sites were built up in 2005. In summary, the research provided multi-arrangement genetic diversity parameters , genetic background for germplasm resources conservation and utilization of M. azedarach. The construction of core germplasm is positive for scientifical and rational protection of gene resources of M. azedarach.
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