Mutation Breeding for Crop Improvement

Abstract

Crop improvement programmes through induced mutations were initiated about seven decades ago, immediately after the discovery of mutagenic effects of X-rays on Drosophila by Muller in 1927, and barley and maize by Stadler in 1928. During 1950–60, several countries including China, India, the Netherlands, USA and Japan took up the task of crop improvement through mutation breeding approaches. A coordinated programme on mutation breeding was also initiated in rice in south east Asia in 1964 by IAEA. Over 2252 mutant varieties of crop plants including cereals, oilseeds, pulses, vegetables, fruits, fibres and ornamentals have been developed by the end of the 20th century. More than 60% of these mutant varieties were developed and released after 1985. While 1585 varieties were released as direct mutants, the rest were released through cross breeding with mutants. Most of the mutant varieties (around 89 %) have been developed using physical mutagens (X-rays, gamma rays, thermal and fast neutrons), with gamma rays alone accounting for the development of 60 % of the mutant varieties. A wide range of characters which have been improved through mutation breeding include plant architecture, yield, flowering and maturity duration, quality and tolerance to biotic and abiotic stresses. Mutation breeding has made a significant contribution to the national economy of the countries like China, India, Japan, Pakistan and USA. With the release of more than 305 mutant cultivars belonging to 56 plant species, India has also become a major recognised centre for work on induced mutations and the second largest contributor of the mutant varieties in the world. In recent years interest has rekindled in mutation research, since induced mutagenesis is gaining importance in plant molecular biology as a tool to identify and isolate genes and to study their structure and function. These studies will definitely have a major impact on the future crop improvement programmes.