意大利的水稻黄化病研究

 年以来,水稻黄化病(Giallume)已成为意大利水稻上的一种危险性病害。它是由禾谷缢管蚜,麦长管蚜和麦无网长管蚜非专化性传播的大麦黄矮病毒RGV株引起的病害。目前种植的老品种都感病,产量损失5-100%。
水稻感染大麦黄矮病毒后的典型症状是叶片退色成黄色至橘红色,病叶主脉黄化,分蘖减少,病株矮缩,花器枯萎,以至坏死。
RGV株系为典型的持久性类型,经过循迥期后。蚜虫可传毒较长时间。除稗(Echinochloa crusgalli)、稻状李氏禾(Leersia oryzoides)为病毒寄主外,栽培的禾谷类作物,如玉米,燕麦也是RGV寄主。

OCCURRENCE OF BARLEY YELLOW DWARF VIRUS ON RICE IN ITALY

"Giallume" (yellowing) (RG) is a dangerous disease of rice present in Italy since 1965, The disease is found also in Spain.
It was demonstiated that RG is caused by a severe strain of the luteovirus Barley Yellow Dwarf Virus (BYCV)non specifically transmitted by Rhopalosiphum padi, Sitobion avenae and Metopolophium dirhodum, the former being the most efficient vector.
According to the results obtained in comparative aphid-transmissions and with serological tests (ELISA, monoclonal antibodies) the RG agent is similar to the USA PAV strain of BYDV as is also the Chinese PAVG strain.
Some italian rice varieties are very susceptible to RGV and others are highly tolerant (symptomatically resistant) but none are really immune or resistant to BYDV. Symptoms of RG can vary according to the rice variety. Maize aud avena are also symptoms-showing hosts of RGV. Another BYDV strain isolated from maize did not iuduce any obvious symptom on infected rice varieties though these latter reacted positively to ELISA.
The natural cycle of the disease is mainly based on spontaneous plants (i.e.Leersia oryzoides), rice (a good host for R. padi, too) and the chief aphid vector.
The disease can be prevented by vector and weed control but most effectively by using tolerant rice genotypes.