Identification Of Malvastrum Leaf Curl Virus

There are many reports about begomoviruses isolated from plants growing in Fujian in recent years. We collected leaves samples showing typical symptoms of begomovirus from Xianyou and Yong'an of Fujian Province. We extracted the total DNA, used the degenerate primer pair PA/PB to amplify fragements from viral DNA genome and then sequenced them. The analysis of sequences indicated that F1 is an isolate of Malvastrum leaf curl virus (MaLCV) and F2 is an isolate of Alternanthera yellow vein virus (AlYVV).The isolate F1 was isolated from Malvastrum coromandelianuml in Xianyou of Fujian Province exhibiting symptoms of MaLCV. The complete nucleotide sequence of the DNA-A molecule of F1 is determined to be 2748 nucleotides and contains 6 ORFs. F1 DNA-A is most closely related to isolates of MaLCV and Papaya leaf curl virus (PaLCuV) with 88%~96% identities, while less than 80% identities are found in comparisons with other begomoviruses. Therefore, F1 is taxonomically considered as an isolate of MaLCV.The isolate F2 was isolated from Eclipta prostrata in Yong'an of Fujian Province expressing symptoms of AlYVV. The complete nucleotide sequence of the DNA-A molecule of F2 is determined to be 2745 nucleotides and have 6 ORFs. F2 DNA-A is most closely related to isolates of AlYVV with 92%~97% identities, while less than 75% identities are found in comparisons with other begomoviruses. Therefore, F2 is taxonomically considered as an isolate of AlYVV.We constructed infectious clone of MaLCV and inoculated healthy Nicotiana benthamiana, Lycopersicon esculentum and Nicotiana tobacum. Nicotiana benthamiana showing symptoms of MaLCV was used to infect healthy Malvastrum coromandelianuml. Symptom of leaf up-curling started to appear 6 days after agroinoculation in inoculated plants confirming the infectivity of the obtained clones. The inoculated Nicotiana benthamiana showed leaf curl, vein thicken and dwarfsm compared with the control at 30 dpi. The inoculated Malvastrum coromandelianuml and Lycopersicon esculentum just showed slightly leaf up-curling at 30 dpi. However, the inoculated Nicotiana tobacum did not show any symptom at 30 dpi.