Genetic Structure of Rice Blast Pathogen Magnaporthe oryzae in Sichuan Province

doi:10．3969/j．issn．1001G7216．2015．03．013

Abstract

Abstract:

Rice blast, caused by Magnaporthe oryzae, is one of the most destructive disease worldwide. The genetic structure of five populations of M. oryzae, collected from Mianyang, Yingshan, Ya’an, Beichuan and Wusheng of Sichuan Province, were analyzed using six fluorescent labeled SSR markers. A total of 43 polymorphic alleles were produced in 124 isolates of M. oryzae. The mean number of observed alleles (Na) and effective alleles (Ne) per locus were 7.2 and 3.1, respectively, and all loci exhibited significant deviations from Hardy-Weinberg equilibrium. The mean observed heterozygosity (Ho = 0.374) was lower than expected (He = 0.502), indicating the deficit of heterozygotes resulting from the accumulation of inbreeding within populations. Analysis of molecular variance showed that the majority (81.17%) of genetic variation was attributed to the differences among isolates within population, with only 18.83% of the variation resulting from differences among populations. High levels of genetic differentiation (Fst, 0.057-0.528) existed among all five geographical populations. Mantel test revealed no significant correlation between the genetic and geographical distances for all populations (r = -0.201, P = 0.587), indicating that the genetic variation of M. oryzae populations was randomly distributed in geographic space. Different levels of gene flow (Nm,0.472 - 4.347), occurred between populations, were also verified by Bayesian-based clustering algorithm analysis by Structure.

Key words: rice blast disease, Magnaporthe oryzae, genetic diversity, genetic structure, SSR marker

摘要：

由稻瘟病菌(Magnaporthe oryzae)侵染引起的稻瘟病是全球水稻生产上最严重的病害之一。利用6对SSR荧光标记对采自四川绵阳、营山、雅安、北川和武胜地区的5个稻瘟病菌群体的遗传结构进行分析。结果表明,在124个稻瘟病菌中检测出43个等位基因,平均每个位点的观测等位基因数为7.2,有效等位基因数为3.1,所有位点均显著偏离Hardy-Weinberg平衡。5个群体的平均观测杂合度(0.374)低于期望杂合度(0.502),暗示群体内存在因近交而导致的杂合子缺失。AMOVA分析显示,绝大多数遗传变异(81.17%)存在于群体内个体间,仅有18.83%的变异来自于群体间的差异。5个地理群体间呈现高水平的遗传分化(遗传分化系数为0.057~0.528)。Mantel检验表明,群体间的遗传距离与地理距离相关未达显著水平,说明稻瘟病菌的遗传变异呈现随机分布的空间模式。群体遗传学数据分析表明5个群体间存在不同程度的基因流(基因流水平为0.472~4.347),基于贝叶斯聚类法的Structure分析也证实了这一结果。

关键词: 稻瘟病, 稻瘟病菌, 遗传多样性, 遗传结构, SSR标记

CLC Number:

S435.111.4⁺1

Ling WANG, Shi-min ZUO, Ya-fang ZHANG, Zong-xiang CHEN, Xue-biao PAN, Shi-wen HUANG. Genetic Structure of Rice Blast Pathogen Magnaporthe oryzae in Sichuan Province[J]. Chinese Journal OF Rice Science, 2015, 29(3): 327-334.

王玲, 左示敏, 张亚芳, 陈宗祥, 潘学彪, 黄世文. 四川省稻瘟病菌群体遗传结构分析[J]. 中国水稻科学, 2015, 29(3): 327-334.

Figures/Tables 10

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来源地 Sampling locality	样本数量 Sample size	纬度 Latitude (N)/°	经度 Longitude (E)/°
绵阳 MY	32	31.47	104.67
营山 YS	30	31.08	106.56
雅安 YA	31	29.98	103.01
北川BC	12	31.62	104.47
武胜 WS	19	30.35	106.29

来源地 Sampling locality	样本数量 Sample size	纬度 Latitude (N)/°	经度 Longitude (E)/°
绵阳 MY	32	31.47	104.67
营山 YS	30	31.08	106.56
雅安 YA	31	29.98	103.01
北川BC	12	31.62	104.47
武胜 WS	19	30.35	106.29

标记 Marker	观测等位基因数 Na	有效等位基因数Ne	Shannon’s 信息指数I	观测杂合度 Ho	期望杂合度 He	哈-温平衡偏离程度P
pyrms 81-82	7	1.8	0.840	0.516	0.439	0.000
pyrms 99-100	8	3.2	1.412	0.943	0.689	0.000
pyrms 125-126	7	2.6	1.225	0.000	0.615	0.000
pyrms 233-234	5	1.6	0.778	0.072	0.391	0.000
pyrms 409-410	12	7.4	2.154	0.516	0.869	0.000
pyrms 533-534	4	2.1	0.913	0.274	0.527	0.000
平均值Mean	7.2	3.1	1.220	0.387	0.588	-

标记 Marker	观测等位基因数 Na	有效等位基因数Ne	Shannon’s 信息指数I	观测杂合度 Ho	期望杂合度 He	哈-温平衡偏离程度P
pyrms 81-82	7	1.8	0.840	0.516	0.439	0.000
pyrms 99-100	8	3.2	1.412	0.943	0.689	0.000
pyrms 125-126	7	2.6	1.225	0.000	0.615	0.000
pyrms 233-234	5	1.6	0.778	0.072	0.391	0.000
pyrms 409-410	12	7.4	2.154	0.516	0.869	0.000
pyrms 533-534	4	2.1	0.913	0.274	0.527	0.000
平均值Mean	7.2	3.1	1.220	0.387	0.588	-

来源地 Sampling locality	观测等位基因数 Na	有效等位基因数 Ne	Shannon’s信息指数 I	观测杂合度 Ho	期望杂合度 He
绵阳MY	6.2	3.1	1.299	0.406	0.645
营山YS	2.3	1.6	0.445	0.472	0.281
雅安YA	3.3	2.6	0.957	0.344	0.558
北川BC	3.5	2.6	0.996	0.319	0.587
武胜WS	3.2	2.2	0.780	0.333	0.439
平均值Mean	3.7	2.4	0.895	0.374	0.502