Bacterial endophytes contribute to abiotic stress adaptation in pepper plants (Capsicum annuumL.)

Abstract

Endophytes are nonpathogenic plant-associated bacteria that can play an important role in plant vitality and may confer resistance to abiotic or biotic stress. The effects of 5 endophytic bacterial strains isolated from pepper plants showing 1-aminocyclopropane-1-carboxylate deaminase activity were studied in sweet pepper under in vitro conditions. Four of the strains tested showed production of indole acetic acid. Plant growth, osmotic potential, free proline content, and gene expression were monitored in leaves and roots under control and mild osmotic stress conditions. All indole acetate producers promoted growth in Capsicum annuum L. 'Ziegenhorn Bello', from which they were isolated. Osmotic stress caused an increase in the content of free proline in the leaves of both inoculated and noninoculated plants. Inoculated control plants also revealed higher proline levels in comparison with noninoculated control plants. Differential gene expression patterns of CaACCO, CaLTPI, CaSAR82A, and putative P5CR and P5CS genes during moderate stress were observed, depending on the bacterium applied. Inoculation with 2 bacterial strains, EZB4 and EZB8 (Arthrobacter sp. and Bacillus sp., respectively), resulted in a significantly reduced upregulation or even downregulation of the stress-inducible genes CaACCO and CaLTPI, as compared with the gene expression in noninoculated plants. This indicates that both strains reduced abiotic stress in pepper under the conditions tested.

Plant Beneficial Microbes and Their Application in Plant Biotechnology

“…In these plants, genes linked with ethylene metabolism under abiotic stress were down-regulated (Sziderics et al, 2007). Because Bacillus sp.…”

Regulation of Ethylene Level in Mungbean (Vigna radiata L.) by 1-Aminocyclopropane-1-Carboxylic Acid (ACC)-Deaminase containing Bacterial Strain under Salt Stress

“…Asterisks denoting P value of significance (** P ≤ 0.01; *** P ≤ 0.001; **** P ≤ 0.0001). A high level of proline under abiotic stresse has been reported in the presence of beneficial bacteria such as, Burkholderia (Porcel and Ruiz-Lozano2004), Arthrobacter (Sziderics et al, 2007) and Bacillus (Gururani et al, 2013). Salinity stress induced the accumulation of soluble sugars in the plants that are contributed to the plant tolerance under salt stressed condition (Trotel-Aziz et al, 2000).…”

Halotolerant Plant Growth Promoting Bacteria Mediated Salinity Stress Amelioration in Plants

“…Bacterial osmolytes, such as glycine betaine act synergistically with plant osmolytes, accelerating osmotic adjustment. Proline synthesis, has shown increase in abiotic stressed plants in the presence of beneficial bacteria such as Burkholderia (Barka et al, 2006), as well as Arthrobacter and Bacillus (Sziderics et al, 2007); however, in pepper, proline also accumulated in the absence of abiotic stress in Arthrobacter and Bacillus treated plants, suggesting that these bacteria cause biotic stress on the pepper (Sziderics et al, 2007). Glycine-betaine produced by osmo-tolerant bacteria act synergistically with plant produced glycine-betaine in response to the stress, and this way, increase osmotic stress tolerance.…”