Hydrogen sulphide alleviates root growth inhibition induced by phosphate starvation

Phosphorus (P) has crucial roles in plant growth and development. Hydrogen sulphide (H₂S) has multiple functions in plants, particularly having the ability to promote tolerance to a variety of adversity stresses. However, it is unclear whether H₂S has a function when plants suffer Pi-deficiency stress. DES1, encoding L-cysteine desulfhydrase1, is a crucial source of H₂S in Arabidopsis thaliana by catalysing the substrate L-cysteine. Under phosphate starvation, the des1 mutant had a significantly shorter primary root length than the wild-type Col-0, and exogenous application of H₂S donor NaHS could compensate for the root growth-sensitive phenotype. In contrast, the transgenic lines DES1ox overexpressing DES1 exhibited less sensitivity to phosphate starvation in terms of longer roots compared to the Col-0. These results demonstrate that H₂S is involved in the regulation of Arabidopsis root growth under phosphate starvation. Moreover, using quantitative real-time polymerase chain reaction experiments to analyse the changes in genes induced by phosphate starvation in des1 mutant and Col-0, we screened to find that the expression of the Sulfoquinovosyl diacylglycerol 1 (SQD1) gene was significantly downregulated in the des1 mutant. Consistently, exogenous H₂S significantly promoted SQD1 expression levels in roots of Col-0. Taken together, we demonstrate that DES1-mediated H₂S participates in alleviating root growth inhibition by promoting the expression of SQD1 under Pi starvation.