Research Center of Genetic Resources, NARO

Visualizing diversity in mechanisms of salt tolerance

- Road to super-salt-tolerant crop with various mechanisms of salt tolerance in wild relatives of azuki bean -

The National Agriculture and Food Research Organization (NARO), in collaboration with National Institutes for Quantum Science and Technology (QST), the University of Tokyo and University of Tsukuba, has visualized distribution of sodium in plants exposed to salt stress in four salt-tolerant species of azuki bean relatives and revealed that each species exhibited a particular pattern of salt allocation. This indicated that these four species have different mechanisms of salt tolerance from each other. By combining two or more of such various mechanisms, it would be possible to develop a super-salt-tolerant crop, which could be a solution to freshwater shortage.


Overview

Agriculture industry consumes more freshwater than any other industries, but freshwater is a limited resources including groundwater. In areas with limited rainfall, people have to deplete groundwater for irrigation, which is far from being sustainable. Some even predicts that demands for drinking water and irrigation would compete each other.

One solution for the problems of freshwater shortage is developing crops that can be grown with salt water. In addition to seawater, reserves of brackish water are much more abundant compared to fresh groundwater. Therefore, crops that can be hydroponically cultivated using salt water would help reducing freshwater use in agriculture. This is why many scientists have challenged to develop salt-tolerant crops and succeeded in creating plants that can survive even in seawater. However, in the context of food production, we need crops that not only survive but also grow well in salinized water.

Therefore, in order to discover genetic resources that contribute to developing new crop varieties with excellent salt tolerance, a research group from NARO, QST, the University of Tokyo and University of Tsukuba, has investigated salt tolerance mechanisms of four wild relatives of azuki bean that grow coastal environments and show high salt tolerance. To do so, the research team applied autoradiograph techniques, which visualize radiation that is invisible to human eyes. After feeding radioisotopes of sodium (radioactive sodium) to the plants, the technique enabled to acquire visual image of sodium distribution in the plant bodies. The analyses revealed that the four relatives of azuki bean exhibit totally different patterns of sodium allocation. This is the first achievement in the world to demonstrate the diversity of mechanisms of salt tolerance in crop wild relatives.

Based on the results of this research, it will be possible to identify genes that are responsible for those mechanisms of salt tolerance. If the genes are identified, it will be possible to introduce multiple mechanisms of salt tolerance into a crop, making it even more tolerant to salt stress than the wild relatives. Such crops will contribute to saving freshwater resources.


Publication

Diversity of Na+ allocation in salt-tolerant species of the genus Vigna. Noda Y, Sugita R, Hirose A, Kawachi N, Tanoi K, Furukawa J and Naito K. Breeding Science 72 (4) pp326-331. https://doi.org/10.1270/jsbbs.22012


For Inquiries

Contact: https://www.naro.go.jp/english/inquiry/index.html

Centers・Institutes