Genetic Screening and Expression Analysis of Psychrophilic Bacillus spp. Reveal Their Potential to Alleviate Cold Stress and Modulate Phytohormones in Wheat

Abstract

Abiotic stress in plants pose a major threat to cereal crop production worldwide and cold stress is also notorious for causing a decrease in plant growth and yield in wheat. The present study was designed to alleviate cold stress on plants by inoculating psychrophilic PGPR bacteria belonging to Bacillus genera isolated from extreme rhizospheric environments of Qinghai-Tibetan plateau. The genetic screening of psychrophilic Bacillus spp. CJCL2, RJGP41 and temperate B. velezensis FZB42 revealed presence of genetic features corresponding to cold stress response, membrane transport, signal transduction and osmotic regulation. Subsequently, the time frame study for the expression of genes involved in these pathways was also significantly higher in psychrophilic strains as analyzed through qPCR analysis at 4 ℃. The inoculated cold tolerant Bacillus strains also aided in inducing stress response in wheat by regulating abscisic acid, lipid peroxidation and proline accumulation pathways in a beneficial manner. Moreover, during comparative analysis of growth promotion in wheat all three Bacillus strains showed significant results at 25 ℃. Whereas, psychrophilic Bacillus strains CJCL2 and RJGP41 were able to positively regulate the expression of phytohormones leading to significant improvement in plant growth under cold stress.

The Type III Accessory Protein HrpE of Xanthomonas oryzae pv. oryzae Surpasses the Secretion Role, and Enhances Plant Resistance and Photosynthesis

“…The rice plants treated with PXO99 A and sterilized with double distilled water were used as controls. The time frame study for consumption of CO 2 as well as light usage depicting photosynthetic activity, transpiration rate and stomatal conductance of rice plants was performed by using the readings from seven maximum light exposed leaves from three plants of each treatment post inoculation (at an interval of 2, 4 and 6 dpi) by using an open IRGA LI-COR 6400 XT portable photosynthesis system (LI-6400, Li-Cor Inc., Lincoln, NE, USA) [34]. All parameters under study were recorded under light saturated conditions at 380 mol mol −1 CO 2 concentration and a photosynthetic photon flux density of 1000 mmol photons m −2 s −1 .…”

Isolation and Identification of Soil Bacteria from Extreme Environments of Chile and Their Plant Beneficial Characteristics

“…Bacteria of the genus Arthrobacter , Bacillus , Janthinobacterium , Pseudomonas , and Sporosarcine , among others, have been described as having different mechanisms associated with cold stress tolerance, such as cold acclimation proteins (Caps) and antifreezing proteins (AFPs) that protect the specific cytoplasmic and extracellular components involved in cold adaptation [ 55 ]. In addition, a study by Zubair et al [ 67 ] showed that the Bacillus genus presents mechanisms of response to cold stress through the formation of biofilms, the production of Reactive Oxygen Species (ROS), and also through the expression of the acdS gene, which is related to the ACC deaminase activity committed to the PGP capacity.…”

Microbial Diversity of Psychrotolerant Bacteria Isolated from Wild Flora of Andes Mountains and Patagonia of Chile towards the Selection of Plant Growth-Promoting Bacterial Consortia to Alleviate Cold Stress in Plants

“…NARs9 compared to 71% control germination, after 7 days at 18 • C. Yarzábal et al [26] showed an increase of around 32% in the length of roots of wheat seeds treated with the Antarctic Pseudomonas sp. CIBEA71 compared to the control treatment, after 5 days at 16 • C. Zubair et al [27] reported that the treatment with Bacillus strains increases the vigor index of wheat seeds after 7 days at 14 • C.…”

“…CIBEA71 compared to the control treatment, after 5 days at 16 °C. Zubair et al [ 27 ] reported that the treatment with Bacillus strains increases the vigor index of wheat seeds after 7 days at 14 °C.…”

“…On the other hand, the formulation of bacterial consortia (≥2 compatible bacteria) can increase the efficiency of agricultural crop production particularly under challenging environmental conditions, due to exploitation of their complementary and synergistic characteristics, compared to a single bacterium [ 15 , 16 ]. Various studies report plant growth-promoting effects with the application of a single bacterium, such as Pseudomonas , Bacillus , Serratia , Pantoea , and Paraburkholderia strains on canola, wheat, grapevine, and tomato under cold stress [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. The formulation of bacterial consortia to alleviate cold stress in plants has been scarcely reported.…”