Identification And Evaluation On Genetic Diversity Of Common Wild Rice In Zhangpu County Fujian Province

Common wild rice(Oryza rufipogon Griff.)is ancestor of Asia cultivated rice(Oryza sativa), and is an indispensable parent strain resource for rice breeding, which contains many elite genes like disease-resistance, insect-resistance, adverse-resistance, high-yield and so on. There are 2 Zhangpu wild rice (Oryza rufipogon Griff.) natural populations spread over Huxi She Township in Zhangpu county Fujian province. Populationâ… is located at Shitanhu lake where about 100 meters away from Zhaojiabao village in Huxi She township, populationâ…¡is located at Gutang lake at Lingjiao village in Huxi She township of Zhangpu county, where is the eastern most point of longitude distribution on China mainland for common wild rice. In this study, agronomic traits and cold resistance of Zhangpu wild rice were identified and evaluated comprehensively according to Descriptor and Data Standard for Wild Rice (Oryza sp.), and molecular genetic diversity of Zhangpu wild rice populations was evaluated by SSR (simple sequence repeat) molecular marker technology. Main results obtained were as follows:1. Identification and evaluation on agronomic traits of Zhangpu wild riceGrowth habit of Zhangpu wild rice can be divided into 4 groups, erect (11.76%), semi-erect (33.33%), inclining (29.41%), and creeping (25.49%). Mean of stem length was 111cm, variation range was 78.8~145cm. Mean of transplanting-flowering days was 162d, variation range was 109~193d. Most Spikes had second twigs,94.12%, and 5.88% without second swigs. Mean of spike length was 29.74cm, variation range was 18.75~39.5cm. Mean of anther length was 5.1mm, variation range was 3.8~7.5mm. Mean of spikelet fertility was 78%, variation range was 18%~100%. Mean of grain length was 8.27mm, variation range was 7.06~9.63mm. Mean of 100-seed weight was 1.47g, variation range was 1.12~1.82g. Mean of chalkiness rice rate was 30%, variation range was 0%~80%. Mean of chalkiness size was 14.77%, variation range was 0%~45%.Mean of chalkiness degree was 4.11%, and variation range was 0% ~ 17.6%.Results about correlation analysis on some agronomic traits showed that, 100-seed weight has significant negative correlations with color of basal sheath(r=-0.31*) and spike type(r=-0.29*), and there was also a very significant correlation lied between100-seed weight and grain type(r=0.40**). There was a very significant negative correlation between spikelet fertility and transplanting-heading time(r=-0.43**), a significant negative correlation between spike fertility and color of awn(r=-0.36*), a significant correlation between anther length(r=0.31*) and spikelet fertility, and a significant correlation between grain type(r=0.33*) and spikelet fertility. Flag leaf length (r=0.37**), grain type(r=0.45**) and color of glumes at florescence(r=0.40**) all had a very significant correlation with chalkiness degree, growth habit(r=0.30*) had a significant correlation with chalkiness degree. Furthermore, a significant correlation lied between stem length (r=0.33**) and high tiller. A negative significant correlation lied between flag leaf angle and ear stem length (r=0.32*), a significant correlation lied between spike length (r=0.29*) and flag leaf angle, a very significant correlation lied between anther length (r=0.38**) and flag leaf angle. A significant correlation existed between spike branches and spike type(r=0.30*), and a very significant negative correlation lied between short grain (0.38**) and spike branched.Clustering analysis on agronomic traits showed that, Zhangpu wild rice individuals from different collection points were gathered in different subsets respectively(M1001-M1055 were gathered in subsetâ… , M2001-M2045 were gathered in subsetâ…£), there was a high similarity between two populations of Zhangpu wild rice, however, individuals from different collection points also had distinguishing features and certain degree of differences, plenty of genetic differentiations have happened inside the two populations.2. Identification and evaluation on cold resistance of Zhangpu wild riceThere were 31 individuals in Zhangpu wild rice populationâ… , of them, 13 were high resistance(HR) individuals, occupied 41.94%; 11 were resistance(R) individuals, occupied 19.35%; 1 were middle sensitive (MS) individual, occupied 3.23%. There were 26 individuals in Zhangpu wild rice populationâ…¡, of them, 7 were HR individuals, occupied 26.92%. 2 were R individuals, occupied 7.69%. 5 were MR, occupied 19.23%. 4 were MS, occupied 15.38%. 8 were sensitive(S), occupied 30.77%.With check individuals, cold resistance of all test individuals were, Zhangpu wild rice>japonica rice>indica rice. Cold resistance of common wild rice were, Hainan wild rice>Zhangpu wild rice. Cold resistance of 2 Zhangpu wild rice populations were, Shihutang lake population(populationâ… )>Gutang lake population (populationâ…¡).3. Evaluation on genetic diversity of Zhangpu wild rice with SSR molecular mark In 21 SSR locus detected, Zhangpu wild rice has a higher average numbers of alleles (A), was 3.5238, average numbers of effective alleles (Ae) was 2.0054. Next was Hainan wild rice, A=2.8095, Ae=2.0124, and was higher than that of Zhangpu wild rice.Average expected heterozygosity (He) of common wild rice in 2 areas was 0.3943, 0.3943, respectively. Average observed heterozygosity (Ho) was 0.2493, 0.2597, respectively. Shannon-wiener diversity index (I) was 0.7918, 0.7465, respectively. The sort order of genetic diversity of 2 regional populations was, Zhangpu wild riceï¹¥Hainan wild rice, in descending order.SSR clustering analysis showed that, at Euclidean Distance 9.73, all common wild rice can be divided into two groups, Zhangpu wild rice gathered in one group, Hainan wild rice gathered in another group. At Euclidean Distance 7.29, Zhangpu wild rice can be further divided into two groups, at Euclidean Distance 5.02; they can be further divided into four groups, which mean that, ample genetic differentiations have occurred within Zhangpu wild rice populations.Variation range degree of Zhangpu wild rice intra-population deviated from Hardy-Weinberg equilibrium (Fis) was -0.0303~1.0000, mean of which was 0.4304 that means slight deviation from Hardy-Weinberg equilibrium (Fis) of intra-population, majority of locus (57.96%) were heterozygote. Average allelic variation (A) was 3.5238, effective allelic variation (Ae) was 2.0054, average expected heterozygosity (He) was 0.3943, observed heterozygosity (Ho) was 0.2593, Shannon-wiener diversity index (I) was 0.7918. Variation range of out crossing rate(t) estimated by fixation index(F) was 0.0000~1.2240, mean of which was 0.3892, that indicated the breeding system of Zhangpu wild rice was a kind of mass mating system with a high inbreeding rate.