Complexity of begomovirus and betasatellite populations associated with chilli leaf curl disease in India

Abstract

Chilli, which encompasses several species in the genus Capsicum, is widely consumed throughout the world. In the Indian subcontinent, production of chilli is constrained due to chilli leaf curl disease (ChiLCD) caused by begomoviruses. Despite the considerable economic consequences of ChiLCD on chilli cultivation in India, there have been scant studies of the genetic diversity and structure of the begomoviruses that cause this disease. Here we report on a comprehensive survey across major chilli-growing regions in India. Analysis of samples collected in the survey indicates that ChiLCD-infected plants are associated with a complex of begomoviruses (including one previously unreported species) with a diverse group of betasatellites found in crops and weeds. The associated betasatellites neither enhanced the accumulation of the begomovirus components nor reduced the incubation period in Nicotiana benthamiana. The ChiLCD-associated begomoviruses induced mild symptoms on Capsicum spp., but both the level of helper virus that accumulated and the severity of symptoms were increased in the presence of cognate betasatellites. Interestingly, most of the begomoviruses were found to be intra-species recombinants. The betasatellites possess high nucleotide variability, and recombination among them was also evident. The nucleotide substitution rates were determined for the AV1 gene of begomoviruses (2.60610 23 substitutions site 21 year 21 ) and the bC1 gene of betasatellites [chilli leaf curl betasatellite (ChiLCB), 2.57610 24 substitution site 21 year 21 ; tomato leaf curl Bangladesh betasatellite (ToLCBDB), 5.22610 24 substitution site 21 year 21 ]. This study underscores the current understanding of Indian ChiLCD-associated begomoviruses and also demonstrates the crucial role of betasatellites in severe disease development in Capsicum spp.

Nicotiana benthamiana phosphatidylinositol 4‐kinase type II regulates chilli leaf curl virus pathogenesis

“…Geminiviruses constitute the largest group of plant viruses that are recognized for detrimental losses of economically important crops like tomato, cotton, cassava, maize and chickpea (Moffat, 1999). Chilli leaf curl virus (ChiLCV) is a ssDNA-containing monopartite virus, species Chilli leaf curl virus, genus Begomovirus, family Geminiviridae, that causes chilli leaf curl disease (ChiLCD), which is characterized by leaf curling, leaf distortion, crinkling of leaves and stunting of plants, and results in significant yield loss Kumar et al, 2015).…”

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“…Most of the begomoviruses found in Thailand possess bipartite genomes but the routine detection of DNA-B has been relatively more difficult than the detection of DNA-A. The RCA method provided advantages in amplifying circular viral genome in the samples and facilitate the cloning of mono-or bi-partite virus genomes from either plant tissue or whitefly body [24,32]. In Indonesia both monopartite and bipartite begomoviruses causing leaf curl in chili pepper were reported and artificial inoculation of chili pepper with DNA-A and DNA-B of PepYLIV had been confirmed in disease induction [13,14,33,34].…”

Silencing of tomato CTR1 provides enhanced tolerance against Tomato leaf curl virus infection

“…Besides severely damaging tomato cultivation, the ToLCJoVs are known to infect other important plants such as kenaf and chilli. 10,11 Being monopartite in nature, the ToLCJoV infection is associated with Betasatellite, a subviral DNA molecule which encodes important pathogenicity determinants. 12,13 Generally, ethylene (ET) plays a vital role in antiviral defense in various plants.…”