Hanaa A. Abo-Kora ( 2016). Endophytic colonization of maize (Zea mays v.) root plants by PGPRs under salinity stress.Nature and Science,14(7 ) :34-51
Abstract: Endophytic bacteria are a group of bacteria that actively colonize plant roots and increase plant growth and yield. The current investigation succeeded to isolate 18 entophytic bacterial isolates were isolated from roots of Zea mays v. plants grown in saline soil, and evaluate the efficiency of these isolates on the growth parameters of maize plant grown on sterilized saline soil. In vitro, colonization predominantly on root hair zones was studied after 30 days from sowing. All of the obtained isolates were screened for their tolerance to against different concentrations of sodium chloride (0.1, 1, 10, 20, 30 and 50 Mm), bacterial growth and nitrogenase activity were determined. Six active tolerant isolates were identified by 16S rDNA sequencing 3 of them identified as Bacillus polymyxa and the others identified as Azospirillum brasilense. The selected strains were tested in sperm sphere model and electron microscopy to investigate the colonization patterns of endophytic bacteria on the roots of zea mays plant. Pot experiment, was conducted during summer 2012 at Agricultural Research Center (ARC) Giza, Egypt, to evaluate the efficacy of these endophytes on the growth and productivity under salt stress conditions. Results indicated that the mixture of endophytic bacteria strains significantly increased growth parameters of maize plants. The plants inoculated with these bacteria showed increase in photosynthetic pigments, enzymatic activities. Proline content decreased significantly by inoculation of maize plant with endophytic bacteria when applied individually and or in mixture. The endophytic bacteria significantly improved growth and yield components. The increase in total carbohydrates (62.41mg/g and crude protein (4.81%) respectively as compared to control (uninoculated). Moreover, mixture of endophytic bacterial strains increased 100-grain weight (37.12g), nitrogen, phosphorus and potassium contents in grains in comparison with control. Therefore, these six strains under study are considered good candidates as plant growth promoter’s endophytes in maize plants.
Keywords: (Endophytic bacteria, Zea mays v., salt stress, colonization patterns, transmission electron microscopy, growth characters, yield.)
