Minghui Liu, Bili Cao, Jin-Wei Wei, Biao Gong

Summary

Although saline–alkali stress can improve tomato quality, the detailed molecular processes that balance stress tolerance and quality are not well-understood.

Our research links nitric oxide (NO) and γ-aminobutyric acid (GABA) with the control of root malate exudation and fruit malate storage, mediated by aluminium-activated malate transporter 9/14 (SlALMT9/14). By modifying a specific S-nitrosylated site on pyruvate-dependent GABA transaminase 1 (SlGABA-TP1), we have found a way to enhance both plant's saline–alkali tolerance and fruit quality.

Under saline–alkali stress, NO levels vary in tomato roots and fruits. High NO in roots leads to S-nitrosylation of SlGABA-TP1/2/3 at Cys316/258/316, reducing their activity and increasing GABA. This GABA then reduces malate exudation from roots and affects saline–alkali tolerance by interacting with SlALMT14. In fruits, a moderate NO level boosts SlGABA-TP1 expression and GABA breakdown, easing GABA's block on SlALMT9 and increasing malate storage. Mutants of SlGABA-TP1C316S that do not undergo S-nitrosylation maintain high activity, supporting malate movement in both roots and fruits under stress.

This study suggests targeting SlGABA-TP1Cys316 in tomato breeding could significantly improve plant's saline–alkali tolerance and fruit quality, offering a promising strategy for agricultural development.

Paper Linkage:https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.19693