| In this study,59morphological characteristics’phenotypic diversity of49example varieties which listed as example varieties in the DUS testing guidelines was studied; genetic diversity based on DNA fingerprint of the49example varieties and949rice test materials was analyzed by using24rice SSR primers recommended by testing guidelines; The clustering analysis for the example varieties and test varieties was conducted according to their phenotypic and genotypic diversity parameters; the stability and the importance of morphological characteristics for the example varieties in rice DUS testing was also analyzed. It aims to evaluate the current DUS test example varieties, the morphological test characteristics and SSR markers in the DUS testing guidelines, and to provide a criterion for selection and optimization of example varieties, morphological test characteristics and SSR markers in rice DUS testing system; it could also give a reference for developing DUS testing guidelines for other plant species. The main results are as follows:(1) Diversity analysis, including observed number of alleles, effective number of alleles and Shannon’s information index, were conducted with49rice varieties which listed as example varieties in the DUS testing guidelines as materials, combining with the59morphological characteristics investigated at Hanzhou in2008. The clustering analysis for the example varieties was also conducted according to their species diversity parameters. The results showed that total of201and262alleles for59morphological characteristics were observed in the indica and japonica rice group, respectively, with an average of3.4068and4.4407alleles for each characteristic in the two subspecies. The Shannon’s diversity index averaged from59morphological characteristics was0.8318with a range of0-1.7674and0.9828with a range of0-1.8547in the indica and japonica rice group, respectively. Several groups, with each includes2-3rice varieties with similarity over0.7, were found in both indica and japonica rice group, based on the clustering results. The results indicated that the49example varieties, which with rich diversity in morphological characteristics, could be used for demonstration and adjusting for characteristics’ describing in DUS testing.(2) DNA fingerprinting and genetic diversity were conducted with49rice varieties which listed as example varieties in the DUS testing guidelines as materials, combining with24SSR markers. The clustering analysis for the example varieties was also conducted according to their species diversity parameters. The results showed that the total of141and156alleles for24SSR markers were observed in the indica and japonica rice group, respectively, with an average of5.88and6.50alleles for each marker in the two subspecies. The Shannon’s diversity index averaged for24SSR markers were1.5141with a range of1.0460-1.9959and1.4389with a range of1.4389in the indica and japonica rice group, respectively. Several groups, with each includes2-3rice varieties with similarity over0.65, were found in both indica and japonica rice group, based on the clustering results. The results indicated that the49example varieties, which with rich diversity based on DNA fingerprint, could be used for demonstration and adjusting for SSR markers in DUS testing. The49rice example varieties could be reduced to46combined with the results of morphological characteristics and genotypic cluster analysis.(3) DNA fingerprinting and genetic diversity were conducted with949rice test varieties as materials, combining with the24SSR markers. The clustering analysis for the example varieties was also conducted according to their species diversity parameters. The results showed that a total of227alleles for24SSR markers were observed in the949rice varieties, with an average of9.46alleles for each marker. The Shannon’s diversity index averaged for24SSR markers were1.4783with a range of0.8872-2.0841. Most of the markers are suitable for DUS test, a very small part of the SSR markers’diversity was relatively poor, such as RM274and RM85, it is recommended to develop new SSR markers. The cluster analysis showed that the949test rice varieties can be roughly divided into two large groups of indica and japonica according the threshold with similarity of0.3, and this classification was consistent with the varieties’sources information. Most of the test varieties’genetic similarity coefficient was greater than0.7; and a total of126test varieties’genetic similarity coefficient was above0.8, which indicated these varieties showed close genetic distance. Some test varieties’genetic coefficient was above0.95, which indicated the narrow genetic basis of current rice breeding. Among them, the genetic similarity coefficient of4rice groups was100%and their morphological characteristics also didn’t show significant differences, field phenotypic identification was needed to decide whether they are the same rice varieties.(4) The stability analysis of DUS testing characteristics were conducted with49rice varieties which listed as example varieties in the DUS testing guidelines as materials, combining with AMMI model. The results showed that the stability of the35visual characteristics are relatively high, but there are some differences between different characteristics, the Di values ranged from0.028to0.886. The15morphological characteristics, such as glum length, leaf roll degree have high stability; the Di values were all below0.1. While the leaf hairs and phimosis degree have relatively low stability, they showed large variability in different environments. In a whole, the stability of measured characteristics was worse than the visual characteristics. Some of the measured characteristics’stability was relatively low, such as seed setting rate, stem length, heading date, grains per panicle and maturity date, the stability parameter Di was more than0.5. The importance parameters of the characteristics by measurement observation were greater than the characteristics by visual observation.(5) The51morphological characteristics of44rice varieties which listed as example varieties in the DUS testing guidelines were investigated by different nitrogen treatment. The results showed that application amount of nitrogen had varying degrees affects on visual characteristics and measured characteristics. Among them,38visual characteristics, such as heading date, leaf green degree and internodes anthocyanin coloration had obvious response to nitrogen, other visual characteristics had relatively better stability. The length of the longest awn had better stability among the13measurement indexes; other characteristics all had significant change in different nitrogen fertilizer levels. |
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