A few sequence polymorphisms among isolates of Maize bushy stunt phytoplasma associate with organ proliferation symptoms of infected maize plants.
A few sequence polymorphisms among isolates of Maize bushy stunt phytoplasma associate with organ proliferation symptoms of infected maize plants.
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DOI：
10.1093/aob/mcw213
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发表时间：
2017-03-01
期刊：
影响因子：
4.2
通讯作者：
Hogenhout SA
中科院分区：
文献类型：
--
作者：
Orlovskis Z;Canale MC;Haryono M;Lopes JRS;Kuo CH;Hogenhout SA
背景与目的玉米丛矮植原体（Maize bushy stunt phytoplasma， MBSP）是一种分布于拉丁美洲的玉米病原菌。MBSP属“Candidatus Phytoplasma”属16SrI-B亚群。MBSP及其媒介虫媒少女圆蚧（半翅目：圆蚧科）仅限于玉米；两者都被认为是在玉米从类似大刍草的祖先驯化过程中与玉米共同进化的。感染mbsp的玉米植株表现出多种症状。在巴西广泛种植的玉米杂交种上，MBSP很可能受到强选择，从而增加了毒力和昆虫传播。在这项研究中，研究了来自巴西东南部两个玉米种植区的MBSP分离株的基因组序列差异是否解释了MBSP分离株在不同玉米基因型上的症状严重程度差异。方法采集巴西东南部Guaíra和Piracicaba玉米生产田中分离株进行感染检测。选择一个有代表性的分离物进行从头全基因组组装，并对其他植物原体分离物的基因组序列进行比对，以检测多态性。采用统计学方法研究了侵染玉米植株病害症状变异与MBSP序列多态性的相关性。主要结果：MBSP分离株与器官增生症状和玉米基因型一致，导致侵染玉米植株叶片坏死、变红、变黄。症状差异与相位可变脂蛋白（候选效应蛋白）和atp依赖性脂蛋白ABC输出蛋白的多态性有关，而在其他候选效应基因中未观察到多态性。脂蛋白和ABC输出蛋白激活宿主防御反应，调节病原体对宿主细胞的附着，激活其他病原体的效应分泌系统。结论：来自巴西东南部玉米种植区的MBSP分离株中两个假定毒力基因的多态性与感染MBSP的玉米植株器官增殖症状的变异有关。
Background and Aims Maize bushy stunt phytoplasma (MBSP) is a bacterial pathogen of maize (Zea mays L.) across Latin America. MBSP belongs to the 16SrI-B sub-group within the genus ‘Candidatus Phytoplasma’. MBSP and its insect vector Dalbulus maidis (Hemiptera: Cicadellidae) are restricted to maize; both are thought to have coevolved with maize during its domestication from a teosinte-like ancestor. MBSP-infected maize plants show a diversity of symptoms. and it is likely that MBSP is under strong selection for increased virulence and insect transmission on maize hybrids that are widely grown in Brazil. In this study it was investigated whether the differences in genome sequences of MBSP isolates from two maize-growing regions in South-east Brazil explain variations in symptom severity of the MBSP isolates on various maize genotypes. Methods MBSP isolates were collected from maize production fields in Guaíra and Piracicaba in South-east Brazil for infection assays. One representative isolate was chosen for de novo whole-genome assembly and for the alignment of sequence reads from the genomes of other phytoplasma isolates to detect polymorphisms. Statistical methods were applied to investigate the correlation between variations in disease symptoms of infected maize plants and MBSP sequence polymorphisms. Key Results MBSP isolates contributed consistently to organ proliferation symptoms and maize genotype to leaf necrosis, reddening and yellowing of infected maize plants. The symptom differences are associated with polymorphisms in a phase-variable lipoprotein, which is a candidate effector, and an ATP-dependent lipoprotein ABC export protein, whereas no polymorphisms were observed in other candidate effector genes. Lipoproteins and ABC export proteins activate host defence responses, regulate pathogen attachment to host cells and activate effector secretion systems in other pathogens. Conclusions Polymorphisms in two putative virulence genes among MBSP isolates from maize-growing regions in South-east Brazil are associated with variations in organ proliferation symptoms of MBSP-infected maize plants.