Importance of secondary inoculum of Plasmopara viticola to epidemics of grapevine downy mildew
Importance of secondary inoculum of Plasmopara viticola to epidemics of grapevine downy mildew
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DOI：
10.1111/j.1365-3059.2005.01208.x
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发表时间：
2005-08-01
期刊：
影响因子：
2.7
通讯作者：
Gessler, C
中科院分区：
文献类型：
--
作者：
Gobbin, D;Jermini, M;Gessler, C
为了量化葡萄藤霜霉病次生孢子囊的大小和空间传播，4685个葡萄生单轴霜霉病单病变样品收集了18个地块遍布中欧。在2000年至2002年期间，每个地块在2至22个采样日期收集疾病症状。四个多等位基因微卫星标记用于病原体样品的基因型鉴定。遗传分析显示，超过2300个位点特异性的葡萄生疫霉基因型，表明种群是遗传丰富的人口统计单位。在各种流行病中，大约70%的基因型被采样一次，14%被采样两次。在18个群体中，只有7个基因型（0.3%）被鉴定超过50次。三种基因型在次级周期中特别成功地引起疾病，主要表现出聚集分布。孢子囊的迁移距离小于20 m，定殖率约为1-2 m（2）d（-1）。因此，葡萄藤的霜霉病流行是多种基因型相互作用的结果，每种基因型引起有限的（或少数）病变，并且是能够在小区尺度上逐步传播的显性基因型的结果。这些发现与目前关于葡萄藤霜霉病流行病学的理论形成对比，该理论假设存在一种基因型和孢子囊长距离迁移的大规模葡萄园定殖。
To quantify the magnitude and the spatial spread of grapevine downy mildew secondary sporangia, 4685 Plasmopara viticola single lesion samples were collected from 18 plots spread across central Europe. Disease symptoms were collected on two to 22 sampling dates per plot between 2000 and 2002. Four multiallelic microsatellite markers were used for genotypic identification of pathogen samples. Genetic analysis showed more than 2300 site-specific P. viticola genotypes, indicating that populations are genetically rich demographic units. Approximately 70% of the genotypes were sampled once and 14% were sampled twice throughout the various epidemics. In the 18 populations only seven genotypes (0.3%) were identified more than 50 times. Three genotypes particularly successful in causing disease through secondary cycles showed mainly a clustered distribution. The distance of sporangial migration per secondary cycle was less than 20 m and their plot colonization rate was calculated at around 1-2 m(2) day(-1). Downy mildew epidemics of grapevine are therefore the result of the interaction of a multitude of genotypes, each causing limited (or a few) lesions, and of a dominant genotype able to spread stepwise at plot-scale. These findings contrast with current theories about grapevine downy mildew epidemiology, which postulate that there is massive vineyard colonization by one genotype and long-distance migration of sporangia.