Li Shu, Hao Weijia, Lu Guanghua, Huang Jilei, Liu Chuanhe, Zhou Guohui
Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, Guangdong 510642, China.
Instrumental Analysis and Research Center, South China Agricultural University, Guangzhou, Guangdong 510642, China.
Plant Dis. 2015 Nov;99(11):1483-1487. doi: 10.1094/PDIS-12-14-1243-RE. Epub 2015 Sep 11.
Rice orange leaf disease (ROLD) is caused by rice orange leaf phytoplasma (ROLP) and occurs sporadically in rice-growing areas in countries of eastern and southeastern Asia. ROLD caused severe damage to rice production in South China in the 1980s. Although its impact subsequently declined in South China, it has reemerged as a serious threat recently. Our study showed that ROLD occurrence varies in different seasons and fields. It was more severe in summer-grown crops (from July to October) than in spring-grown crops (from March to July). In most fields, the incidence was less than 10%, and diseased plants were scattered throughout the fields. In 20% of fields, the incidence was between 10 and 30%. In some fields, over 90% of plants were affected, causing crop failure. Typical symptoms of ROLD include orange-colored leaves and poor growth. Diseased plants were determined as positive for ROLP but negative for Rice tungro bacilliform virus, Rice tungro spherical virus, and Rice transitory yellowing virus through polymerase chain reaction and reverse-transcription polymerase chain reaction. Phytoplasma bodies but not virus-like particles were observed by electron microscopy in phloem tissue of diseased leaves. The leafhopper Inazuma dorsalis, previously identified as the unique vector for ROLP, was rare in the affected fields. Another leafhopper, Nephotettix cincticeps, previously considered a nonvector for this phytoplasma, was very common. Transmission tests revealed that this insect could also transmit ROLP; therefore, it might represent a new vector responsible for the recent incidence of ROLD.
水稻橙叶病（ROLD）由水稻橙叶植原体（ROLP）引起，在东亚和东南亚国家的水稻种植区零星发生。20世纪80年代，水稻橙叶病在中国南方对水稻生产造成了严重破坏。尽管其影响随后在中国南方有所下降，但最近又重新成为一个严重威胁。我们的研究表明，水稻橙叶病的发生在不同季节和田间存在差异。夏季种植的作物（7月至10月）比春季种植的作物（3月至7月）病情更严重。在大多数田间，发病率低于10%，病株分散在整个田间。在20%的田间，发病率在10%至30%之间。在一些田间，超过90%的植株受到影响，导致作物绝收。水稻橙叶病的典型症状包括叶片变黄和生长不良。通过聚合酶链反应和逆转录聚合酶链反应，确定病株对水稻橙叶植原体呈阳性，但对水稻东格鲁杆状病毒、水稻东格鲁球状病毒和水稻暂黄病毒呈阴性。在病叶韧皮部组织中，通过电子显微镜观察到了植原体，但未观察到病毒样颗粒。叶蝉电光叶蝉（Inazuma dorsalis）曾被确定为水稻橙叶植原体的唯一传播媒介，在受影响的田间很少见。另一种叶蝉黑尾叶蝉（Nephotettix cincticeps），以前被认为不是这种植原体的传播媒介，却非常常见。传播试验表明，这种昆虫也能传播水稻橙叶植原体；因此，它可能是导致近期水稻橙叶病发生的一种新传播媒介。
