Drought stress imposes a serious threat to crop productivity and nutritional security.Drought adaptation mechanisms involve complex regulatory network comprising of various sensory and signaling molecules. In this context, melatonin has emerged as a potential signaling molecule playing a crucial role in imparting stress tolerance in plants. Melatonin pretreatment regulates various plant physiological processes such as osmoregulation, germination, photosynthesis, senescence, primary/secondary metabolism, and hormonal cross-talk under water deficit conditions. Melatoninmediated regulation of ascorbate-glutathione (AsA-GSH) cycle plays a crucial role to scavenge reactive oxygen species generated in the cells during drought. Here, in this review, the current knowledge on the role of melatonin to ameliorate adverse effects of drought by modulating morphological, physiological, and redox regulatory processes is discussed. The role of melatonin to improve water absorption capacity of roots by regulating aquaporin channels and hormonal cross-talk involved in drought stress mitigation are also discussed. Overall, melatonin is a versatile bio-molecule involved in growth promotion and yield enhancement under drought stress that makes it a suitable candidate for eco-friendly crop production to ensure food security.

No abstract

Potato dry rot disease caused by Fusarium species is a major threat to global potato production. The soil and seed-borne diseases influence the crop stand by inhibiting the development of potato sprouts and cause severe rots in seed tubers, table and processing purpose potatoes in cold stores. The symptoms of the dry rot include sunken and wrinkled brown to black tissue patches on tubers having less dry matter and shriveled flesh. Fungal infection accompanied by toxin development in the rotten tubers raises more concern for consumer health. The widespread dry rot causing fungal species (Fusarium graminearum) is reported to have a hemibiotrophic lifestyle. A cascade of enzymes, toxins and small secreted proteins are involved in the pathogenesis of these hemibiotrophs. With the availability of the genome sequence of the most devastating species Fusarium sambucinum, it is important to identify the potential pathogenicity factors and small secreted proteins that will help in designing management strategies. Limited resistant cultivars and the emergence of fungicide-resistant strains have made it more threatening for potato cultivation and trade. Several novel fungicide molecules (Azoxystrobin, chlorothalonil and fludioxonil), are found very effective as tuber treatment chemicals. Besides, many beneficial bioagents and safer chemicals have shown antibiosis and mycoparasitism against this pathogen. Germplasm screening for dry rot resistance is important to assist the resistance breeding program for the development of resistant cultivars. This review aims to draw attention to the symptomatology, infection process, pathogenomics, the role of toxins and management approaches for potato dry rot disease, which is very much critical in designing better management strategies.

The muga silkworm, Antheraea assamensis, is exclusively present in the northeastern regions of India and rearing of this silkworm is a vocation unique to this region in the world. Through culture-dependent techniques, generic identification using 16S ribosomal RNA probes, diversity analysis and qualitative screening for enzyme activities, our studies have identified a number of bacterial isolates, viz. Bacillus spp., Serratia marcescens, Stenotrophomonas maltophilia, Pseudomonas stutzeri, Acinetobacter sp. and Alcaligens sp., inhabiting the gut of the muga silkworm. Analysis of the culturable bacterial community from the gut of An. assamensis revealed that Bacillus (54%) was the predominant bacterial genus followed by Serratia (24%), Pseudomonas (10%) and Alcaligens (6%). Significant differences in the Shannon-Wiener (H') and Simpson (D) diversity indices of gut bacteria were recorded for An. assamensis collected from different regions. H' and D values were found to be highest for An. assamensis from the Titabar region (H' = 4.73 ± 0.43; D = 10.00 ± 0.11) and lowest for individuals from the Mendipathar region (H' = 2.1 ± 0.05; D = 0.04 ± 0.00) of northeastern India. Qualitative screening for enzyme activities identified about 26 gut bacterial isolates having significantly higher cellulose, amylase and lipase activities. These isolates probably contribute to the digestion and nutrition of their host insect, An. assamensis.

No abstract

No abstract

No abstract

No abstract