Mutagenesis—A Tool for Improving Rice Landraces

Rice is an important staple food for half of the world’s population. Development of high yielding varieties and large-scale cultivation of these varieties resulted in genetic erosion. Climate change is also posing a serious threat to crop cultivation. Unpredictable monsoon, sudden pest and disease outbreak, frequent droughts, floods, etc., increase the pressure to develop resistant genotypes. Traditional landraces are well adapted to local environment, possess resistant genes and some landraces have consumer preference due to aroma, medicinal properties, grain dimensions, etc. But they are late maturing, tall, lodging susceptible and photoperiod sensitive. Mutation breeding is a powerful method for developing new variation. Combining mutation breeding with rice landraces can help in tackling the problem of genetic erosion by genetic improvement of rice landraces. Gamma ray is the most commonly used mutagen in rice. Finding optimum dose (LD₅₀) of mutagen for a given material is essential for a successful breeding program. Trueness of mutants to parent can be confirmed by SSR marked based studies or whole genome sequencing. Mutation studies in rice landraces can also help in understanding gene function of genes responsible for special characters like aroma in rice using forward or reverse genetics. Targeted mutation using CRISPR/Cas technology can be used for understanding gene function.