Culturable bacterial endophytes isolated from citrus leaves enhance seedling growth of Solanum melongena L.

Abstract

Endophytes have a symbiotic relationship with plants and play an important role in supporting the plant growth. The objective of this study was to examine the effect of endophytic bacteria isolated from citrus leaves on promoting seedling growth and influencing some biochemical attributes in brinjal (Solanum melongena L.). Isolated bacteria were characterized based on molecular tool 16S rRNA. The bacterial isolates were identified as Enterococcus faecalis, Brevibacillus borstelensis, Staphylococcus haemolyticus, Bacillus safensis, B. megaterium, B. cereus, Pseudomonas sp., P. aeruginosa, Enterobacter hermachei and Proteus mirabilis based on 16S rRNA sequence homology and phylogenetic analysis. The leaves of brinjal seedlings were inoculated with these bacterial endophytes by injection method under greenhouse conditions. About one month after inoculation, the plants were analysed for their physical (shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight and root dry weight,), bio-physical (chlorophyll a and b contents, and relative leaf water content), and biochemical (total phenolic, flavonoids and carotenoids contents) parameters. In the present study, Bacillus safensis and Pseudomonas sp. significantly increased the shoot length, shoot fresh and dry weights, relative leaf water content, leaf chlorophyll b content, phenolics and flavonoids in brinjal plants after the application of the bacterial inoculum. However, carotenoids content remained unaffected by the bacterial inoculum. Thus, some bacterial endophytes possess prospective potential in improving plant growth and could be used as inoculants to establish a sustainable crop production system.