Emergence of yellowing disease in cucurbitaceous vegetables caused by Crinivirus and Polerovirus in India.

Totally 102 symptomatic samples of cucurbitaceous vegetables showing yellowing were collected from fields of Uttar Pradesh and screened by RT-PCR assay for the presence of Crinivirus and Polerovirus. Among them, Crinivirus (16%) and Polerovirus (23%) were tested positive with the universal primer pairs. Based on the sequence analysis of amplified product, two Crinivirus (Cucurbit chlorotic yellows virus - CCYV and Cucurbit yellow stunting disorder virus - CYSDV) and two Polerovirus (Cucurbit aphid-borne yellows virus - CABYV and Luffa aphid-borne yellows virus - LABYV) species were characterized. Phylogenetic analysis revealed less genetic distance among the Indian isolates of CCYV, CYSDV and LABYV whereas CABYV closely related to Chinese isolates. To the best of our knowledge, this study documents infection of CCYV on cucumber, round melon and muskmelon; CYSDV on satputia and sponge gourd; CABYV on ivy gourd; and LABYV on ridge gourd, satputia and muskmelon for the first time in India.

Molecular characterization of the Indian isolate (Ka-To) of tomato spotted wilt virus (TSWV) infecting tomato (Solanum lycopersicum L.).

Tomato spotted wilt virus (TSWV) infecting tomato has been identified as an emerging constraint for tomato cultivation in the southern Indian states of Karnataka and Tamil Nadu. Infection of TSWV produces circular necrotic ring spots on leaves, stem and floral necrosis and necrotic ringspots on fruits of tomato. In this study, we describe the characterization of TSWV isolate (Ka-To) infecting tomato from India based on biological, serological and molecular assay. Pathogenicity of TSWV (Ka-To) isolate was established by mechanical inoculation of sap from infected leaves on tomato, cowpea and datura which expressed necrotic or chlorotic local lesions. Samples were tested positive in the serological assay performed with TSWV-specific immunostrips. Further, reverse transcription polymerase chain reaction (RT-PCR) amplification of coat protein gene followed by sequencing, unequivocally confirmed the identity of TSWV. The obtained full-length nucleotide sequences of Ka-To isolate [L RNA-MK977648; M RNA-MK977649; and S RNA-MK977650] had greater similarity to the TSWV isolates of Spain and Hungary infecting tomato and pepper. The phylogenetic and recombination analysis showed the evidence for reassortment and recombination in the genome of Ka-To isolate. To the best of our knowledge, this is the first confirmed evidence for the occurrence of TSWV on tomato in India. Information obtained in this study issues a forewarning on the emergence of TSWV on vegetable ecosystem in the Indian subcontinent, requiring urgent management strategies to curtail its pestilence. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03579-y.

Exploration of plant transcriptomes reveals five putative novel poleroviruses and an enamovirus.

Transcriptome datasets available in public domain serve as valuable resource for identification and characterization of novel viral genomes. Poleroviruses are economically important plant-infecting RNA viruses belonging to the family Solemoviridae. In the present study, we explored the plant transcriptomes available in public domain and identified five putative novel poleroviruses tentatively named as Foeniculum vulgare polerovirus (FvPV), Kalanchoe marnieriana polerovirus (KmPV), Paspalum notatum polerovirus (PnPV), Piper methysticum polerovirus (PmPV), Trachyspermum ammi polerovirus (TaPV) and a novel enamovirus named as Celmisia lyallii enamovirus (ClEV) in Foeniculum vulgare, Kalanchoe marnieriana, Paspalum notatum, Piper methysticum, Trachyspermum ammi and Celmisia lyallii, respectively. Coding-complete genomes (5.56-5.74 kb) of CIEV, KmPV, PnPV, PmPV and TaPV were recovered while only the partial genome of FvPV could be recovered. The genome organization of identified viruses except ClEV is 5'-ORF0-ORF1-ORF2-ORF3a-ORF3-ORF4-ORF5-3' while that of ClEV is 5'-ORF0-ORF1-ORF2-ORF3-ORF5-3'. Phylogenetic analysis revealed that poleroviruses of apiaceous plants formed a monophyletic clade within the genus Polerovirus.

Understanding the Plant-microbe Interactions in CRISPR/CAS9 Era: Indeed a Sprinting Start in Marathon.

Plant-microbe interactions can be either beneficial or harmful depending on the nature of the interaction. Multifaceted benefits of plant-associated microbes in crops are well documented. Specifically, the management of plant diseases using beneficial microbes is considered to be eco-friendly and the best alternative for sustainable agriculture. Diseases caused by various phytopathogens are responsible for a significant reduction in crop yield and cause substantial economic losses globally. In an ecosystem, there is always an equally daunting challenge for the establishment of disease and development of resistance by pathogens and plants, respectively. In particular, comprehending the complete view of the complex biological systems of plant-pathogen interactions, co-evolution and plant growth promotions (PGP) at both genetic and molecular levels requires novel approaches to decipher the function of genes involved in their interaction. The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 (CRISPR-associated protein 9) is a fast, emerging, precise, eco-friendly and efficient tool to address the challenges in agriculture and decipher plant-microbe interaction in crops. Nowadays, the CRISPR/CAS9 approach is receiving major attention in the field of functional genomics and crop improvement. Consequently, the present review updates the prevailing knowledge in the deployment of CRISPR/CAS9 techniques to understand plant-microbe interactions, genes edited for the development of fungal, bacterial and viral disease resistance, to elucidate the nodulation processes, plant growth promotion, and future implications in agriculture. Further, CRISPR/CAS9 would be a new tool for the management of plant diseases and increasing productivity for climate resilience farming.

Global Status of Phytoplasma Diseases in Vegetable Crops.

The presence of phytoplasmas and their associated diseases is an emerging threat to vegetable production which leads to severe yield losses worldwide. Phytoplasmas are phloem-limited pleomorphic bacteria lacking the cell wall, mainly transmitted through leafhoppers but also by plant propagation materials and seeds. Phytoplasma diseases of vegetable crops are characterized by symptoms such as little leaves, phyllody, flower virescence, big buds, and witches' brooms. Phytoplasmas enclosed in at least sixteen different ribosomal groups infecting vegetable crops have been reported thus far across the world. The aster yellows phytoplasma group (16SrI) is presently the prevalent, followed by the peanut witches' broom (16SrII). Wide and overlapping crop and non-crop host ranges of phytoplasmas, polyphagous insect vectors, limited availability of resistance sources and unavailability of environmentally safe chemical control measures lead to an arduous effort in the management of these diseases. The most feasible control of vegetable phytoplasma diseases is a consequence of the development and implementation of integrated disease management programs. The availability of molecular tools for phytoplasma identification at the strain level greatly facilitated this kind of approach. It is moreover essential to understand the molecular basis of phytoplasma-vector interaction, epidemiology and other factors involved in disease development in order to reduce the disease outbreaks. Information on the knowledge about the most widespread phytoplasma diseases in vegetable crops is reviewed here in a comprehensive manner.

A specific and sensitive method for the detection of Colletotrichum musae in banana fruit.

BACKGROUND: Banana anthracnose incited by Colletotrichum musae (Berk & Curt.) Arx. is a serious disease both in field and in postharvest marketing stage. Molecular methods are most suitable for the early detection of infection. AIM: The latent infection of C. musae makes it very difficult to detect the infected fruit lot, hence aim is to detect the latent infection using molecular approach. METHODS: The molecular variability generated from fourteen isolates of C. musae by RAPD-PCR technique was utilized to determine the phylogentic relationship and develop SCAR markers. RESULTS: The genetic similarity coefficient within each group and variation between the groups were observed. Decamer OPA-01 generated a RAPD polymorphic profile that distinguished C. musae from the other organism. Cloning and sequencing of the specific band yielded 588bp sequences, to which forward CM-SCAR-FP and reverse CM-SCAR-RP were designed. The SCAR primer pair amplified a single SCAR of 490bp from each of the 14 isolates of C. musae, and was able to detect the pathogen in as low as 30ng of DNA from infected fruit peel tissue. CONCLUSION: The developed SCAR markers can aid the detection process every quickly and accurately which will help exporters.