Alleviating salt stress in tomato seedlings using Arthrobacter and Bacillusmegaterium isolated from the rhizosphere of wild plants grown on saline–alkaline lands

ABSTRACT

Salt-induced soil degradation is common in farmlands and limits the growth and development of numerous crop plants in the world. In this study, we isolated salt-tolerant bacteria from the rhizosphere of Tamarix chinensis, Suaeda salsa and Zoysia sinica, which are common wild plants grown on a saline–alkaline land, to test these bacteria's efficiency in alleviating salt stress in tomato plants. We screened out seven strains (TF1–7) that are efficient in reducing salt stress in tomato seedlings. The sequence data of 16S rRNA genes showed that these strains belong to Arthrobacter and Bacillus megaterium. All strains could hydrolyze casein and solubilize phosphate, and showed at least one plant growth promotion (PGP)-related gene, indicating their potential in promoting plant growth. The Arthrobacter strains TF1 and TF7 and the Bacillus megaterium strain TF2 and TF3 could produce indole acetic acid under salt stress, further demonstrating their PGP potential. Tomato seed germination, seedling length, vigor index, and plant fresh and dry weight were enhanced by inoculation of Arthrobacter and B. megaterium strains under salt stress. Our results demonstrated that salt-tolerant bacteria isolated from the rhizosphere of wild plants grown on saline–alkaline lands could be used for alleviating salt stress in crop plants.

KEYWORDS:

• crop salt stress
• wild halophytes
• rhizosphere bacteria
• salt stress alleviation
• growth promotion

Funding

The authors appreciate support received from the National Natural Science Foundation of China (Project 31401916), National University Student Innovation Program (201510019036), Beijing Fruit Vegetable Innovation Team (GCTDTZ2014033007) and Special Fund for Agro-Scientific Research in the Public Interest (201303014).