تشخیص بتاستلایت پیچیدگی برگ پنبه در داراب، استان فارس

Cotton leaf curl is a serious disease of cotton and other species of Malvaceae, causing major losses to these crops in the tropical regions. The disease is caused by Cotton leaf curl virus (CLCuVin the Begomovirus genus, Geminiviridae family. The presence of a betasatellite molecule) cotton leaf curl betasatellite, CLCuB( is essential for disease symptoms induction. In order to investigate the etiology of cotton leaf curl disease (CLCuD) in Darab located in Fars province, samples were collected from different cotton growing regions during crop season in 2019. Samples included cotton plants showing typical disease symptoms (small leaves and clustering and curling of terminal leaves). Total DNA was extracted from the eaf tissues of collected samples and used in polymerase chain reaction (PCR). Attempts to detect a begomovirus from infected plants using a pair of degenerate primers of begomoviruses including BC primer and primer181V were unsuccessful (It seems that more accurate methods such as Rolling Circle Amplification or RNAseq should be used to isolate the disease-causing begomovirus). However, by using betasatellite specific primer pair Beta01/Beta02, a 1351 bp DNA fragment was amplified from affected cotton plants. Sequence analysis indicated that nucleotide sequence of the amplified fragment (Darab isolate of CLCuB) had a high homology to those of CLCuB isolates from Saudi Arabia and the UAE isolated from okra and cotton plants, respectively. The phylogenetic analysis indicated that Darab isolate of CLCuB had the highest similarity (100%) to Okra leaf curl Gezira betasatellite isolate 12 reported from Saudi Arabia (Acc. KY785329). Also, Darab isolate of CLCuB showed 93/4 % similarity to AL-AIN CLCuB isolated from cotton in the UAE. In a survey conducted on Estahban cotton farms in Fars province by Karimi et al., (2012), it was shown that a betasatellite molecule found in a physalis weed plant designated as cotton leaf curl Iran betasatellite (CLCuIrB) had the highest similarity (100%) with the Samundri betasatellite molecule (Acc. No. FN432359) from Sonchus sp. in Pakistan. Also, it was reported that CLCuIrB had 99.1-99.9% similarity to Multan betasatellite isolates from India and China. The results of these studies show that considering the high similarity of CLCuB isolates of cotton in Fars province, Iran, with betasatellite isolates of Pakistan, Saudi Arabia and UAE and the proximity of these countries to Iran, it can be suggested that different begomovirus/betasatellite complexes involved in CLCuD in the region.