Streptomyces sp. TOR3209 alleviates cold stress in tomato plants

Streptomyces sp. TOR3209 is a plant growth-promoting rhizobacterium for tomato (Solanum lycopersicum L.) plants. This work reports its role in alleviating cold stress in tomato plants. By comparison with the wilting untreated controls, plants receiving TOR3209 treatment grew well at the low temperature of 5°C. To better understand the molecular mechanism induced by TOR3209 under cold stress, RNA sequencing was conducted in both leaf and root tissues to screen the differentially expressed genes. Twenty-nine up-regulated genes at 5°C were classified into three functional groups, such as abscisic acid biosynthesis and stress-related metabolism in roots, and photosynthesis in leaves. The increased amounts of abscisic acid, cold stress metabolites, antioxidants in the roots and increased photosynthetic activities in the leaves were subsequently verified in the plants treated with TOR3209. Our data demonstrate that Streptomyces sp. TOR3209 plays an extra role in promoting cold tolerance of tomato plants by regulating the abscisic acid signalling pathway, stress-related metabolism and photosynthesis.