Plant growth promoting potential of multifarious endophytic Pseudomonas lini strain isolated from Cicer arietinum L.

Chickpea (Cicer arietinum), one of the major pulse crops in India, endured extreme reduction in production due to various abiotic and biotic stresses. Endophytic bacteria residing in the nodules and roots of chickpea plants enable host in combating these stresses. Twenty one endophytic bacteria isolated from nodules and roots of chickpea were screened for multiple plant growth promoting traits like ammonia, organic acid, siderophore, hydrogen cyanide (HCN) and phytohormone indole acetic acid (IAA) production. Out of these, 86% isolates produced ammonia, around 50% isolates produced organic acid, HCN and siderophore, 29% isolates produced ACC (1-aminocyclopropane-1-carboxylic acid) deaminase, while only 14% isolates solubilized phosphate. Interestingly, all the isolates were able to produce IAA ranging from 11.6–85.2 μg/ml, isolate CPJN 13 being the maximum IAA producer (85.5±2.33 μg/ml). Isolate CPJN13 was selected for IAA optimization studies. The yield of IAA increased up to 4 fold i.e. 331±4.96 μg/ml at optimized conditions. IAA production was also confirmed by TLC and HPLC analysis of crude IAA extract. The application of CPJN13 on chickpea seedlings resulted in significant increase in plant growth parameters. The 16S rDNA sequencing of CPJN13 revealed its similarity with Pseudomonas lini strain and submitted to NCBI with accession number MF574502. To best of our knowledge, this is the first report of the presence of P. lini as endophyte in chickpea nodules. The results of this study imply that the endophytic P. lini has a potential role to enhance the plant growth.