Al-Sa'di A M, Deadman M L, Al-Said F A, Khan I, Al-Azri M, Drenth A, Aitken E A B
Department of Crop Sciences, Sultan Qaboos University, P.O. Box 34 Al Khoud 123, Oman.
Jumah Research Station, Ministry of Agriculture, Oman.
Plant Dis. 2008 Feb;92(2):313. doi: 10.1094/PDIS-92-2-0313C.
Muskmelon (Cucumis melo L.) is one of the most important vegetable crops in Oman. In the fall of 2004, sudden wilt was observed in muskmelon grown in a field at Sultan Qaboos University, Muscat. The disease was characterized by rapid collapse of vines and muskmelon plants at the fruit production to maturation stage, associated with brown-to-dark brown rotted primary and secondary roots. The disease resulted in death of more than 85% of muskmelon plants in that field. On potato dextrose agar (PDA), with published methods (1), Pythium spp. were consistently isolated from crowns and roots of plants showing wilt symptoms. Further identification of five isolates of Pythium with sequences of the internal transcribed spacer (ITS) of the ribosomal DNA (1) using ITS1 and ITS4 primers produced a nucleotide sequence 806 bp long, which was identical among all isolates. Comparison with sequences deposited at the National Center for Biotechnology Information revealed 100% nucleotide similarity to a previously published sequence (Accession No. DQ381808) of isolate P091 of P. splendens from cucumber from Oman, for which identification has also been confirmed by morphological characteristics. The sequence of one isolate of P. splendens (P222) was assigned GenBank Accession No. EF546436 and deposited at CBS under Accession No. CBS121855. In pathogenicity tests conducted in a greenhouse, P. splendens induced damping-off symptoms on 7-day-old muskmelon seedlings and also reproduced the same wilt symptoms observed in the field when 2-month-old muskmelon plants were inoculated with 3-day-old P. splendens grown in PDA. To our knowledge, this is the first report of association of P. splendens with wilt of muskmelon in Oman. Reference: (1) A. M. Al-Sa'di et al. Plant Pathol. 56:140, 2007.
甜瓜（Cucumis melo L.）是阿曼最重要的蔬菜作物之一。2004年秋季，在马斯喀特苏丹卡布斯大学一块地里种植的甜瓜上观察到突然萎蔫现象。该病的特征是在果实生产至成熟阶段，藤蔓和甜瓜植株迅速枯萎，伴有主根和次生根从褐色到深褐色的腐烂。该病导致该地块85%以上的甜瓜植株死亡。按照已发表的方法(1)，在马铃薯葡萄糖琼脂（PDA）上，从表现出萎蔫症状的植株的冠部和根部一直分离到腐霉菌。使用ITS1和ITS4引物，通过核糖体DNA内部转录间隔区（ITS）序列对5株腐霉菌分离株进行进一步鉴定，得到一条长度为806 bp的核苷酸序列，所有分离株的该序列均相同。与美国国立生物技术信息中心保存的序列进行比较，结果显示与之前发表的来自阿曼黄瓜的华丽腐霉分离株P091的序列（登录号DQ381808）有100%的核苷酸相似性，其鉴定也已通过形态学特征得到证实。一株华丽腐霉分离株（P222）的序列被赋予GenBank登录号EF546436，并以登录号CBS121855保藏于荷兰真菌生物多样性中心。在温室进行的致病性试验中，华丽腐霉在7日龄甜瓜幼苗上引起猝倒症状，当用在PDA上培养3天的华丽腐霉接种2月龄甜瓜植株时，也再现了在田间观察到的相同萎蔫症状。据我们所知，这是阿曼关于华丽腐霉与甜瓜萎蔫相关性的首次报道。参考文献：(1) A. M. Al-Sa'di等人，《植物病理学》56:140，2007年。
