Screening of Bacterial Endophytes for Osmotolerance and Improvement of Maize Seed Germination under Water Deficit Condition.

Bacterial endophytes present within plant tissues play an important role in maintaining host plant fitness, nutrient supply and mainly to mitigate water deficit stress. In this investigation, it was hypothesized that bacterial endophytes inhabiting the tissues of drought tolerant plants would ameliorate drought stress in maize seed germination. In this study 54 bacterial endophytes were isolated from drought adopted plants collected across different drought prone areas of Karnataka. These endophytes were screened for Osmotolerance using Polyethylene glycol (PEG MW-8000) at 15 and 20 per cent. Out of 54 isolates, five bacterial isolates (P7L1, P2L2, P6R1, P3L2 and P7R1) showed growth in the presence of 20 per cent PEG. These five bacterial isolates were inoculated to pre-germinated maize seeds and incubated in paper towel dipped with 15 per cent PEG. All the five endophytes inoculated seedlings showed increased growth of maize seedlings compared to un-inoculated seedling. However, the P7L1 isolate inoculated seedlings showed significantly increased seedling length than other isolates inoculated seedlings indicating its efficiency against water deficit stress This bacterium isolate was identified as Pseudomonas tolaasii using 16S rRNA gene sequence and its presence in the inoculated seedling was confirmed by re-isolation of bacterium after 10 days of seedling growth and comparing culture with inoculated mother culture both morphologically as well as by 16Sr RNA. [ABSTRACT FROM AUTHOR]