Identification and characterization of a novel begomovirus, Withania leaf curl virus associated with leaf curl disease of Withania somnifera.

Begomovirus is the largest genus of the family Geminiviridae with wide host range and responsible for a considerable amount of economic damage to many important crops globally. Withania somnifera (Indian ginseng) is an important medicinal plant with high demand in pharmaceutical industries worldwide. During the routine survey in 2019, typical characteristic viral symptoms such as severe leaf curling, downward rolling of the leaves, vein clearing, and poor growth of Withania plants with 17-20% disease incidence were observed in Lucknow, India. Typical symptoms, abundant presence of whiteflies, PCR and RCA based detection indicated the amplification of ~ 2.7 kb and suspected the causal pathogen to be a begomovirus, associated with a betasatellite (~ 1.3 kb). Transmission electron microscopy revealed the presence of twinned particles of ~ 18-20 nm in diameter. Full genome sequencing (2758 bp) of the virus and its analysis showed only 88% sequence identity with the begomovirus sequences present in the database. Hence, based on the nomenclature guidelines we concluded that the virus associated with the present disease of W. somnifera is a novel begomovirus and its name is proposed as Withania leaf curl virus.

Emerging threats of begomoviruses to the cultivation of medicinal and aromatic crops and their management strategies.

Begomoviruses (family Geminiviridae) are responsible for extreme yield reduction in a number of economically important crops including medicinal and aromatic plants (MAPs). Emergence of new variants of viruses due to recombination and mutations in the genomes, modern cropping systems, introduction of susceptible plant varieties, global trade in agricultural products, and changes in climatic conditions are responsible for aggravating the begomovirus problems during the last two decades. This review summaries the current research work on begomoviruses affecting MAPs and provides various traditional and advanced strategies for the management of begomoviruses and vector in MAPs.

Eclipta yellow vein virus enhances chlorophyll destruction, singlet oxygen production and alters endogenous redox status in Andrographis paniculata.

The infection of Eclipta yellow vein virus [EcYVV-IN, Accession No. KC476655], recently reported for the first time, on Andrographis paniculata was studied for redox-mediated alteration mechanism in infected plants. A. paniculata, an important medicinal plant, is used in traditional Indian, Chinese and modern system of medicine. Andrographolide, one of the foremost components of this plant, is known for its varied pharmacological properties. Our investigation provides insight into the effect of virus-induced changes in the singlet oxygen quenching due to the alteration in pigment content (chlorophyll and carotenoids) as well as activation of plant secondary metabolism along with defense activation leading to changes in enzymatic and non-enzymatic redox status. Due to infection, a reduction in carotenoid content was observed which leads to reduced quenching of singlet oxygen. An increased level of enzymatic (SOD and APX) and non-enzymatic antioxidant (DPPH, FRAP, RP, NO, TAC and TP) activities were also observed in virus-infected plants with a positive correlation (>0.9). However, CAT activity was diminished which could be either due to its proteolytic degradation or inactivation by superoxide anions (O(2-.)), NO or peroxynitrite radicals. A significant (p < 0.05) increase in total phenolic content was observed in the infected plants while no considerable difference was seen in the total flavonoid content. Our results highlighted the alteration in redox status caused by virus-induced biotic stress on the plants and could be useful for understanding the after effects of viral infection This study could also be helpful in developing biomimetic methods for improving the production of secondary metabolites of pharmaceutical importance.