木瓜輪點病毒(papaya ringspot virus, PRSV)感染木板系統稱爲P系統(PRSV-P),嚴重危害熱帶及亞熱帶木瓜産業。P系統木瓜輪點病毒屬馬鈴薯Y病毒(Potyvirus)群,正極性(positive sense)單股RNA爲10326個核苷酸組成,轉譯成3344個胺基酸之聚蛋白,裂角爲鞘蛋白及內含體(inclusion)等基因産物。五個病毒分離株之鞘蛋白基因有89.6%以上相同。P系統木瓜輪點病毒在50-60℃間不活化,耐稀釋度爲10^(-3)-10^(-5)之間,耐保存性一般爲8-72小時之間,但亦有研究結果達11天之久。木瓜上病徵爲葉片畸形或嵌紋,莖及葉柄統木瓜輪點毒素病可分爲壞疽嵌紋型(SMN)、嚴重嵌紋型(SM)、輕微嵌紋型(M)、畸形重嵌紋型(SMD)及嚴重畸形型(DF)等。該病毒可經機械接種或蚜蟲非永性傳播,不經種子傳病。木瓜輪點毒素病系統性感染木瓜(Carica papaya L.)及部份葫蘆科(Cucurbitaceae)植物,局部感染部份藜科(Chenopodi-aceae)植物。
Papaya strains of papaya ringspot virus (PRSV-P) causes a major disease problem on papaya cultivation in tropics and subtropics. PRSV-P is a member of potyviruses. The positive sense PRSV RNA is 10326 nucleotides in length and is translated into a polyprotein of 3344 amino acids. The cant protein regions of five sequenced PRSV strains shows mom than 89.6% nucleotide identities. The thermal inactivation point of PRSV-P is 50-60℃ within to minutes. Its dilution end point in at 10^(-3)-10^(-5) and with longevity of 8 to 72 hours. It shows leaf deformation and mottles on papaya, water soaked steaks on leaf petioles and stem, and water soaked ringspot on fruit. Strains of PBSV-P from Taiwan include SMN, SM, M, SMD and DF. PRSV-P can be transmitted mechanically and through aphids in a non-persistent manner. Papaya seeds do nut bear virus. Systemic hosts include Carica papaya L, and members of Cucurbitaceae. It causes local lesions on members of Chenopodiaceae.