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Background and aimsCicer anatolicum and C. oxyodon are the perennial chickpea species found in the Kurdistan region of Iran. They have greater drought tolerance than the most drought tolerant cultivars of chickpea (Cicer arietinum). They have not been examined thus far for endophytic bacteria, which could have potential for promoting plant growth and increasing drought stress tolerance. The goal of this study was to isolate and characterize endophytic bacteria from C. anatolicum and C. oxyodon , and then inoculate selected strains on C. arietinum and assess their growth under normal and drought conditions.MethodsEndophytic bacteria were isolated from stems, roots and leaves of two perennial chickpea species and characterized for growth under temperature and drought stress, production of indole acetic acid, 1-aminocyclopropane-1-carboxylic acid deaminase activity, nitrogen fixation, phosphate solubilization, ammonia production, and enzymatic activities of protease, amylase and lipase. Selected isolates were identified using 16S rDNA sequencing, and used to inoculate soil of cultivated chickpea followed by observations of seed germination, growth and development, and photosynthetic pigment contents.ResultsAmong 34 bacterial endophyte isolates from wild perennial chickpeas, in vitro activity was observed for 100% of the isolates for indole acetic acid and ammonia production, 50-60% for phosphate solubilization, protease and amylase activities, 30-40% for nitrogen fixation, lipase, drought tolerance and 1‐aminocyclopropane‐1‐carboxylic acid deaminase, and 23% for heat tolerance. For the 14 isolates with the highest levels of most of those traits, there were five Bacillus species, Micrococcus flavus and Kocuria rosea, all of which have not been reported previously as Cicer endophtyes. Cultivated chickpea, Cicer arietinum, was soil inoculated with isolates Bacillus pumilus COBR7, B. pumilus CAAR3, Bacillus simplex CAAR1 or Bacillus muralis CASR16. With watering, B. pumilus COBR7 most increased seed germination, root/shoot growth and photosynthetic pigments, but with drought, different traits were increased by either B. simplex CAAR1, B. muralis CASR16 or B. pumilus COBR7.ConclusionsCicer anatolicum and C. oxyodon contains bacterial endophytes not yet reported from C. arietinum, some of which promoted plant growth without drought as well as improved drought tolerance of cultivated chickpea in the greenhouse. |
