Hydrogen-rich water enhanced salt tolerance in tomato seedlings by regulating strigolactone biosynthesis genes SlMAX1 and SlD27

Hydrogen gas (H₂) and strigolactones (SLs) are involved in various biotic and abiotic stress response in plants. SlMAX1 and SlD27 are SL biosynthesis genes in tomato. However, the crosstalk between H₂ and SLs has not been investigated.

Using pharmacological methods and virus-induced gene-silencing, the regulatory roles of H₂ and SLs and their interaction in tomato (Solanum lycopersicum L. ‘Micro-Tom’) under salt stress were investigated.

Both GR24 (a SLs synthetic analog) and hydrogen rich water (HRW, a H₂ donor) significantly reversed salt-induced growth retardation as evidenced by promoted root morphological parameters and root activity. SLs might be involved in H₂-enhanced salt stress tolerance in tomato seedling roots. Additionally, HRW treatment increased endogenous SLs content in tomato seedling roots under salt stress However, the positive roles of HRW were blocked by TIS108 (a SLs biosynthesis inhibitor). In addition, HRW and GR24 could effectively maintain the integrity of the internal anatomical structure in roots under salt stress; while TIS108 also inhibited the positive roles of HRW. Thus, Simultaneously, HRW treatment significantly up-regulated the expression levels of SL biosynthesis-related genes SlCCD7, SlCCD8, SlD27 and SlMAX1 and SL signal transduction genes SlD14 and SlMAX2 under salt stress. Further, after silencing SlD27 and SlMAX1 genes, the alleviation effect of HRW on tomato roots under salt stress was basically eliminated. HRW did not increase the content of endogenous SLs in SlD27 and SlMAX1 silenced seedlings.

H₂ may enhance root growth of tomato seedlings under salt stress through regulating SL biosynthesis genes SlD27 and SlMAX1.