Improvement of abiotic stress adaptive traits in mulberry (Morus spp.): an update on biotechnological interventions

Mulberry (Morus spp.), being an economically important tree, is cultivated in China, India, Thailand, Brazil, Uzbekistan and other Countries across the globe, for its leaves to feed monophagous mulberry silkworm (Bombyx mori). The sustainability of silk industry is directly correlated with the production and continuous supply of high-quality mulberry leaves. In India, it is cultivated on large scale in tropical, sub-tropical and temperate regions under irrigated conditions for silkworm rearing. Drought, low temperature, high salinity and alkalinity, being experienced in widespread areas, are the major abiotic stresses, causing reduction in its potential foliage yield and quality. Further, climate change effects may worsen the productivity of mulberry in near future, not only in India but also across the globe. Although traditional breeding methods contributed immensely towards the development of abiotic stress-tolerant mulberry varieties, still there is lot of scope for implementation of modern genomic and molecular biology tools for accelerating mulberry genetic improvement programmes. This review discusses omics approaches, molecular breeding, plant tissue culture and genetic engineering techniques exploited for mulberry genetic improvement for abiotic stress tolerance. However, high-throughput biotechnological tools such as RNA interference, virus-induced gene silencing, epigenomics and genome editing tools need to be utilized in mulberry to accelerate the progress of functional genomics. The application of genomic tools such as genetic engineering, marker-assisted selection and genomic selection in breeding programmes can hasten the development of climate resilient and productive mulberry varieties leading to the vertical and horizontal expansion for quality silk production.