Scientists find new way to make rice resistant to herbicides

By Dr Swati Subodh

New Delhi: Farmers often use toxic chemicals to destroy unwanted vegetation in their fields but such use can also adversely affect yield of crops. Now Indian scientists have found a way of making rice crop tolerant to herbicides.

A consortium of scientists led the Tamil Nadu Agricultural University (TNAU), Coimbatore has identified a novel mutant of rice which can withstand the use of a commonly used broad spectrum herbicide, Imazethapyr.

Herbicides act by disrupting key enzymes and proteins involved in essential processes associated with growth and development of plants. Imazethapyr is a popular herbicide but is not traditionally used on rice fields as it adversely affects the yield.

Over years, many herbicide-tolerant crops, including those resistant to imazethapyr, have been developed but most of them are protected under patents. The mutation identified by the group can be used without restriction in public funded rice breeding.

Scientists used rice variety Nagina 22 in the study since it is already tolerant to heat and drought, and ideally suited for Indian conditions. In this variety, they identified a gene (HTM-N22) and the mutations within it which are responsible for development of tolerance to imazethapyr. This will enable test development for identification of the tolerant variety in rice breeding programs and protect rice cultivation from weeds. In terms of distinctness, uniformity and stability, the tolerant variety appeared indistinguishable, according to results of the study published in journal Rice.

The researchers expect HTM-N22 to have an easy process of registration for widespread commercialization since the development of this mutant did not require genetic engineering of the rice crop. They believe that the most significant use of the herbicide-tolerant mutant will be in its usage in publicly-funded rice breeding programs in India and elsewhere without the fear of infringing intellectual property.

The institutions that participated in TNAU-led project are Indian Agricultural Research Institute, National Research Centre on Plant Biotechnology, Punjab Agricultural University, Indian Institute of Rice Research, University of Agricultural Sciences, Bengaluru; National Rice Research Institute, Cuttack; and National Bureau of Plant Genetic Resources, New Delhi. The network project was funded by Department of Biotechnology. (India Science Wire)