Chlorotic curly stunt: a severe begomovirus disease of bottle gourd in northern India

Abstract

Bottle gourd (Lagenaria siceraria) an important vegetable crop in India was observed to be affected by a chlorotic curly stunt disease (CCSD) during 2003-2006 in the vegetable growing areas of Delhi and adjoining state of Haryana. The affected plants are severely stunted and bear very small chlorotic and mildly curled leaves. Incidence of the disease varied from 4.7 to 36%. The disease could be easily transmitted by whitefly, Bemisia tabaci but not by sap. The causal virus was found to be a Begomovirus on the basis of whitefly transmission and sequence identity of putative coat protein (CP) and replication initiator protein (Rep) genes. The virus was transmitted to Cucumis sativus, Luffa acutangula, L. cylndrica, Lycopersicon esculentum, Nicotiana tabacum and Praecitrullus fistulosus but not to Citrullus lunatus, Cucumis melo, Cucurbita moschata and Vigna unguiculata. The N-terminal 60 amino acids of CP of the virus had 100% sequence identity with all the isolates of Tomato leaf curl New Delhi virus (ToLCNDV) and two isolates of Squash leaf curl China virus (SLCCV). The full length amino acid sequence of the CP and Rep genes had 100% similarity with ToLCNDV-Svr and -Luffa isolates. The phylogenetic analysis showed that the virus associated with CCSD of bottle gourd belongs to ToLCNDV cluster of the begomoviruses. This is the first record of emergence of a Begomovirus associated severe disease in bottle gourd in India.

Keywords: Begomovirus; Bottle gourd; Chlorotic curly stunt; Tomato leaf curl New Delhi virus.

Fig. 1

Disease symptoms of chlorotic curly stunt of bottle gourd (Lagenaria siceraria). a, b Field symptoms. c Greenhouse symptoms following inoculation through whitefly, Bemisia tabaci. d Geminate particles in the diseased leaf of bottle gourd

Fig. 2

Molecular detection of the begomovirus in bottle gourd (Lagenaria siceraria) affected by chlorotic curly stunt disease. a Dot blots of DNA from field samples of bottle gourd hybridized with the radio-labeled probe to CP gene of ToLCNDV-[Luffa]. b, c Polymerase chain reaction showing amplification of putative coat protein (CP) gene (750 bp) in field samples (lanes: 1–4) of bottle gourd (a) and both CP and replication initiator protein gene (1000 bp) in greenhouse sample of BotGn-1 isolate (lanes 1 and 2: with CP primer and lane 3 with Rep primer) (c). M: marker, 1 kb ladder (MBI Fermentas); +ve: positive control; −ve: negative control

Fig. 3

Phylogenetic relationship of the begomovirus associated with the bottle gourd chlorotic curly stunt disease (BotGn-1 isolate) with selected begomoviruses based on a N-terminal 60 amino acids sequence of putative coat protein and b complete amino acids sequence of putative replication initiator protein. Trees were constructed using the ClustalW algorithm of the DNASTAR with the gap weight of 10 and gap length of 0.2