Genetic diversity: the key to protecting rice crops

Plant resistance to disease is a major challenge for modern agriculture and food security. To fight pathogens effectively, plants have powerful defense mechanisms and extensive immune receptor repertoires to identify molecules produced by pathogens. When pathogens escape detection, they can proliferate and cause disease and considerable damage in crops.

Crop monocultures, where vast areas are cultivated with genetically identical plants, offer a terrain which is propitious to disease propagation. Such is the case with rice crops (Oryza sativa) which are particularly susceptible to diseases such as blast, caused by the fungus Magnaporthe oryzae. While modern rice varieties are highly susceptible to disease, traditional varieties—also referred to as landraces—cultivated in the Yuanyang terraces in China, are more resistant to pathogens. Farmers in this region grow almost 200 different types of rice, with a genetic diversity which favours sustainable disease resistance. 

A study recently published in Current Biology by researchers from INRAE, CIRAD and their British and Chinese colleagues, as part of the Plantomix International Associated Laboratory, explored the diversity of the immune receptors in nine traditional and eleven modern varieties. The results of their research show a greater diversity in the genetic sequences of these receptors in traditional varieties compared with modern varieties. The study thus highlights the importance of genetic diversity in traditional rice varieties, making crops and agroecosystems less prone to disease and consequently less dependent on pesticides.