Implications of plant growth promoting Klebsiella sp. CPSB4 and Enterobacter sp. CPSB49 in luxuriant growth of tomato plants under chromium stress.

The present study explores the potential of two chromium tolerant and plant growth promoting bacterial strains, Klebsiella sp. and Enterobacter sp. in luxuriant growth of tomato plants under chromium stress conditions. For the assessment of potentiality of the two selected strains, a pot scale experiment was setup with tomato plant under different levels of chromium contamination. In pot experiment, different plant growth parameters, oxidative stress tolerance and chromium bioremediation potential were studied upon inoculation of the selected bacterial strains. The results of pot experiment showed that both the strains were effective in promotion of plant growth and enhanced the plant biomass but Enterobacter sp. was more prominent in enhancement of root length, shoot length, fresh and dry weight, and nutrient uptake in tomato plant. The enhancement of enzymes to combat oxidative stress in tomato plant under chromium stress was also observed for both the strains. Both strains enhanced the levels of superoxide dismutase, catalase, peroxidase, total phenolic, and ascorbic acid in tomato plant under different levels of chromium stress conditions. The chromium phytoremediation potential of tomato plant upon inoculation of both the strains was also studied. The results of phytoremediation showed greater chromium accumulation in roots with poor translocation in shoot upon inoculation of Klebsiella sp. while no significant enhancement in chromium uptake by tomato plant was observed on inoculation of Enterobacter sp. compared to control. Thus, these two strains can effectively be used in luxuriant growth of tomato plant under metal stress conditions.

Gupta P ，Kumar V ，Usmani Z ，Rani R ，Chandra A ，Gupta VK ... -  《-》

A comparative evaluation towards the potential of Klebsiella sp. and Enterobacter sp. in plant growth promotion, oxidative stress tolerance and chromium uptake in Helianthus annuus (L.).

Prevalence of metal pollutants exerts negative effects on human health and environment, thus propounding an urgent need for a safer substitute. This study was conducted to compare the chromium bioremediation and plant growth promotion ability of two bacterial strains, Klebsiella sp. strain CPSB4 (MH266218) and Enterobacter sp. strain CPSB49 (MH532567), isolated from the rhizospheric soils. A pot scale experiment was setup with Helianthus annuus (L.) as a test plant to compare the efficiency of both isolates in enhancement of plant growth, nutrients uptake, anti-oxidative enzymes production, lipid peroxidation, and chromium bioremediation. Inoculation of strains, CPSB4 and CPSB49 enhanced plant biomass, plant growth, nutrient uptake, anti-oxidative enzymes, and chromium bioremediation, while reduction in lipid peroxidation was observed compared to uninoculated control under chromium stress. The maximum increase in plant growth and nutrient uptake was found in treatments inoculated with CPSB49, while maximum chromium uptake by sunflower was observed in treatments inoculated with CPSB4. Moreover, an increase in anti-oxidative enzyme production and decrease in lipid peroxidation was observed on inoculation of the selected strains. Thus, the strains Klebsiella sp. and Enterobacter sp. can be effectively used in chromium bioremediation and plant growth promotion under chromium stress conditions.

Gupta P ，Kumar V ，Usmani Z ，Rani R ，Chandra A ，Gupta VK ... -  《-》

Potential applications of Pseudomonas sp. (strain CPSB21) to ameliorate Cr(6+) stress and phytoremediation of tannery effluent contaminated agricultural soils.

Gupta P ，Rani R ，Chandra A ，Kumar V ... -  《Scientific Reports》

Tomato ethylene sensitivity determines interaction with plant growth-promoting bacteria.

Plant growth-promoting bacteria (PGPB) are soil micro-organisms able to interact with plants and stimulate their growth, positively affecting plant physiology and development. Although ethylene plays a key role in plant growth, little is known about the involvement of ethylene sensitivity in bacterial inoculation effects on plant physiology. Thus, the present study was pursued to establish whether ethylene perception is critical for plant-bacteria interaction and growth induction by two different PGPB strains, and to assess the physiological effects of these strains in juvenile and mature tomato ( Solanum lycopersicum ) plants. An experiment was performed with the ethylene-insensitive tomato never ripe and its isogenic wild-type line in which these two strains were inoculated with either Bacillus megaterium or Enterobacter sp. C7. Plants were grown until juvenile and mature stages, when biomass, stomatal conductance, photosynthesis as well as nutritional, hormonal and metabolic statuses were analysed. Bacillus megaterium promoted growth only in mature wild type plants. However, Enterobacter C7 PGPB activity affected both wild-type and never ripe plants. Furthermore, PGPB inoculation affected physiological parameters and root metabolite levels in juvenile plants; meanwhile plant nutrition was highly dependent on ethylene sensitivity and was altered at the mature stage. Bacillus megaterium inoculation improved carbon assimilation in wild-type plants. However, insensitivity to ethylene compromised B. megaterium PGPB activity, affecting photosynthetic efficiency, plant nutrition and the root sugar content. Nevertheless, Enterobacter C7 inoculation modified the root amino acid content in addition to stomatal conductance and plant nutrition. Insensitivity to ethylene severely impaired B. megaterium interaction with tomato plants, resulting in physiological modifications and loss of PGPB activity. In contrast, Enterobacter C7 inoculation stimulated growth independently of ethylene perception and improved nitrogen assimilation in ethylene-insensitive plants. Thus, ethylene sensitivity is a determinant for B. megaterium , but is not involved in Enterobacter C7 PGPB activity.

Ibort P ，Molina S ，Núñez R ，Zamarreño ÁM ，García-Mina JM ，Ruiz-Lozano JM ，Orozco-Mosqueda MDC ，Glick BR ，Aroca R ... -  《-》

The effects of dark septate endophyte (DSE) inoculation on tomato seedlings under Zn and Cd stress.

Zhu L ，Li T ，Wang C ，Zhang X ，Xu L ，Xu R ，Zhao Z ... -  《-》