Salt tolerant endophytic bacteria from Carthamus tinctorius and their role in plant salt tolerance improvement
Salt tolerant endophytic bacteria from carthamus tinctorius and their role in plant salt tolerance improvement
Amany M. M. Reyad et al.,
Endophytes | ACC deaminase activity
Vol: 3; Iss: 12; Dec 17 | ISSN: 2454-5422
Eight halotolerant endophytic bacterial species were isolated from root, stem, and leaf of Carthamus tinctorius (safflower) plant. Eight isolates were selected according to further examination of their salt tolerance, and using 1-aminocyclopropane-1-carboxylic acid (ACC) as a sole nitrogen source. Two isolates from the total are able to utilize ACC as a sole nitrogen source and they were tested for (ACC) deaminase activity. The bacterial isolates were characterized and identified using 16S ribosomal DNA technique as Bacillus cereus and Bacillus aerius. Our study results showed that Bacillus cereus and Bacillus aerius were capable of consuming nearly ACC concentration in the DF-ACC medium after 24h incubation. This character of the capability of ACC utilization is related with plant growth promotion due to lowering stress ethylene level. This study suggested that the bacterial strains B. cereus (LB1) and B. aerius (SB1) are valuable biological plant growth promoters that could enhance salt tolerance in safflower plants under 100, 200, and 300 mmol l-1 NaCl levels resulting in an increase in plant growth and chemical composition, in comparison with the non-inoculated controls. Seedling irrigated with different concentrations of NaCl showed significant decreases in IAA and GB, while ethanol content was significantly increased compared to the control. In our studies the used bacterial strains have the ability to achieve systemic tolerance via production of ACC (1-amino cyclopropane-1-carboxylase) deaminase which has the ability to reduce the production of stress hormone ethylene. Our findings reported that the co-inoculation of the two selected endophytic bacteria strains were successfully isolated from safflower seedlings significantly alleviated the harmful effects of salt stress, promoted plant growth and biomass yield.