Cucumo-and tospoviruses are the most destructive viruses infecting hot pepper (chilli). A diagnos... more Cucumo-and tospoviruses are the most destructive viruses infecting hot pepper (chilli). A diagnostic survey was conducted to assess the prevalence of cucumo and tospoviruses in chilli growing tracts of Tamil Nadu. Infected plants showing mosaic with chlorotic and necrotic rings, veinal necrosis, mosaic mottling, leaf filiformity and malformation were collected. Molecular indexing carried out through reverse transcription polymerase chain reaction (RT-PCR) with coat protein gene specific primer of Cucumber mosaic virus (CMV) and tospovirus degenerate primer corresponding to the L segment (RdRp). Ostensibly, amplifications were observed for both CMV and tospoviruses as sole as well for mixed infections. The sequence analysis indicated that the Capsicum chlorosis virus (CaCV) and Groundnut bud necrosis virus (GBNV) to be involved with CMV in causing combined infections. The co-infection of CMV with CaCV was detected in 10.41% of the symptomatic plant samples and combined infection of CMV with GBNV was recorded in around 6.25% of the symptomatic plants surveyed. The amino acid substitution of Ser 129 over conserved Pro 129 in coat protein of CMV implies that CMV strain involved in mixed infection as chlorosis inducing strain. Further, the electron microscopy of symptomatic plant samples explicated the presence of isometric particles of CMV and quasi spherical particles of tospoviruses. This is the first molecular evidence for the natural coexistence of chlorosis inducing CMV strain with CaCV and GBNV on hot pepper in India. The hot pepper commonly known as chilli (Capsicum annuum L.) is the most important spice crop with significant commercial value throughout the world due to its great phenotypic, horticultural, agricultural and biological diversity 1. India is one of the world's largest producer, consumer and exporter of chillies globally. Chilli is reported to be affected by more than 30 economically important viruses by causing 15-50% of yield losses in chilli cultivation 2,3. It includes Cucumber mosaic virus 4 , Chilli leaf curl virus 5 , Tomato spotted wilt virus 6 , Groundnut bud necrosis virus 7 , Capsicum chlorosis virus 8 , Tobacco mosaic virus 9 , Potato virus Y 6 , Tomato leaf curl New Delhi virus 10 and Chilli veinal mottle virus 11. Among them the cucumo and tospoviruses are the most predominant viruses reported to infect almost all the vegetables crops and pose serious threat to chilli production 12. CMV (genus Cucumovirus; family Bromoviridae) consist of isometric particles having sense, ssRNA genome with tripartite segment designated as RNA1, RNA2 and RNA3 13. CMV causes severe mosaic symptoms like leaf distortion and fruit lesions which affect the significant marketable yield of chilli 14. Tospoviruses (genus Orthotospovirus; family Bunyaviridae) are also isometric, ambi-sense, ssRNA virus with tripartite genome of small (S), medium (M) and large (L) segment 15. The symptoms appeared on young leaves as chlorotic lesions later turns to necrotic lesions or yellow spots coalesce to form mosaic pattern and develops concentric rings on mature leaves and fruits 12. Basically, infection may be caused by a single virus or mixed infection by more than one virus together by forming disease complex 7. In general, dynamics of mixed infection with two or more unrelated viruses are common in nature 16. Indeed, mixed infection of CMV with Potato virus Y 17 , CMV with Pepper mottle virus 16,18 , CMV with Turnip yellow mosaic virus 19 , CMV with Watermelon mosaic virus 20 , CMV with Tomato leaf curl New Delhi virus 21 and Cucurbit yellow stunting disorder virus with Zucchini yellow mosaic virus 22 have been reported previously. The mixed infection allows diverse virus interactions and maintenance of viral genetic diversity. Symptoms induced by mixed viral infections were more severe than the single viral infection 16,23. Besides, mixed infections tend to affect virulence, accumulation, symptomology and host range which ultimately results in unpredictable pathological consequences 24,25. Moreover, virus interaction in host plant
Sesame (Sesamum indicum L.) is an important oilseed crop cultivated in various parts of the world... more Sesame (Sesamum indicum L.) is an important oilseed crop cultivated in various parts of the world. Alternaria sesami is a devastating fungal pathogen that causes significant yield losses in sesame crops worldwide. The survey conducted revealed a maximum disease incidence of 55.00 percent at Namakkal. Alternaria sesami was isolated from the leaf blight-infected sesame leaves. Trichoderma viride recorded significant results against Alternaria sesami in vitro. T1R2 showed the highest percent inhibition over control (PIOC) (77.77%) on mycelial growth of Alternaria sesami. 72.22 and 67.77 percentages of inhibition were recorded in T1R1 and T1R3, respectively.
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Papers by Abirami R.