Biotechnology of mulberry (Morus L.) - A review

Abstract

Mulberry (Morus sp.) is one of the economically important trees grown in Asian countries. It is cultivated to provide leaves for feeding the caterpillars of the silk producing insect (Bombyx mori L.). In addition, it adds value through production of edible fruits, timber and several pharmaceutically important chemicals. Improvement of mulberry through conventional breeding is limited due to high heterozygosity and long generation period. Attempts have recently been made to complement conventional breeding with modern biotechnological tools such as plant tissue culture, recombinant DNA technology and molecular markers to facilitate mulberry genetic improvement. The techniques of tissue culture have grown considerably in mulberry and encompassed areas including micropropagation, plant regeneration from leaf discs, and screening for stress tolerance. Recently, genetic engineering was adopted to enhance drought and salt tolerance in mulberry using HVA1 and Osmotin genes. Molecular markers such as Random amplified polymorphic DNA (RAPD), inter simple sequence repeats (ISSR) and simple sequence repeats (SSR) have been used for molecular characterization of mulberry germplasm, biodiversity analysis, genetic mapping and identification of molecular markers for growth and yield . However, still a number of issues such as resistance to fungal and bacterial diseases, combating infestation of pests and insects, and tolerance to drought and salinity are to be sorted out to achieve sustainable mulberry cultivation to meet the increasing demand of the silk industry. This review describes the developments of tissue culture, transgenesis and molecular markers in mulberry and highlights the current constraints and future prospects.