Drought response of <i>Mucuna pruriens</i> (L.) DC. inoculated with ACC deaminase and IAA producing rhizobacteria - Fig 1

<p>Phylogenetic dendrograms showing the relationship between the selected bacterial strains with closely related taxa of <i>Enterobacter</i> (a) and <i>Bacillus</i> (b), respectively, inferred from 16S rRNA sequences. The dendrograms were generated using the Neighbour-Joining method.</p

Drought response of <i>Mucuna pruriens</i> (L.) DC. inoculated with ACC deaminase and IAA producing rhizobacteria - Fig 5

<p>Effect of the severe water stress (FSTW₁₀) on ethylene emission (nl g^-1 h^-1 dry weight) from leaves (a) and roots (b) of velvet bean plants grown in soil inoculated with <i>Enterobacter</i> spp. and <i>Bacillus</i> spp., or uninoculated. Values are means of five plants ± SE, letters indicate significant differences among treatments (<i>P</i> < 0.05).</p

Plant biometric measurements at the end of the experiment (day 10) of velvet bean plants grown in soil inoculated with <i>Enterobacter</i> spp. and <i>Bacillus</i> spp., or uninoculated.

<p>Values are the mean of 10 plants. Different letters indicate significant differences among treatments (one-way ANOVA, Tukey test) for each parameter (<i>P</i> < 0.05).</p

Drought response of <i>Mucuna pruriens</i> (L.) DC. inoculated with ACC deaminase and IAA producing rhizobacteria

<div><p>Drought is one of the major constraints limiting agricultural production worldwide and is expected to increase in the future. Limited water availability causes significant effects to plant growth and physiology. Plants have evolved different traits to mitigate the stress imposed by drought. The presence of plant growth-promoting rhizobacteria (PGPR) could play an important role in improving plant performances and productivity under drought. These beneficial microorganisms colonize the rhizosphere of plants and increase drought tolerance by lowering ethylene formation. In the present study, we demonstrate the potential to improve the growth of velvet bean under water deficit conditions of two different strains of PGPR with ACCd (1-Aminocyclopropane-1-Carboxylate deaminase) activity isolated from rainfed farming system. We compared uninoculated and inoculated plants with PGPR to assess: a) photosynthetic performance and biomass; b) ACC content and ethylene emission from leaves and roots; c) leaf isoprene emission. Our results provided evidence that under drought conditions inoculation with PGPR containing the ACCd enzyme could improve plant growth compared to untreated plants. Ethylene emission from roots and leaves of inoculated velvet bean plants was significantly lower than uninoculated plants. Moreover, isoprene emission increased with drought stress progression and was higher in inoculated plants compared to uninoculated counterparts. These findings clearly illustrate that selected PGPR strains isolated from rainfed areas could be highly effective in promoting plant growth under drought conditions by decreasing ACC and ethylene levels in plants.</p></div

Isoprene emission from leaves of velvet bean plants grown in soil inoculated with <i>Enterobacter</i> spp. and <i>Bacillus</i> spp., or uninoculated.

<p>The measurements were made at 100%, 60% and 10% of fraction of transpirable soil water (FTSW). Values are means of five plants ± SE, letters indicate significant differences among treatments at the same FTSW, while asterisks (_*) indicate significant difference among uninoculated, inoculated with <i>Enterobacter spp</i>. and inoculated with <i>Bacillus spp</i>. plants in the three FTSW levels (<i>P</i> < 0.05).</p

Effect of <i>Enterobacter</i> spp. and <i>Bacillus</i> spp. soil inoculation on photosynthesis (<i>A</i>) and stomatal conductance (<i>g</i>_s) in velvet bean plants under drought stress as a function of fraction of transpirable soil water (FTSW).

<p>Values are averages ± SE of five replicates (plants). Asterisks (_*) indicate significant differences among treatments (<i>P</i> < 0.05).</p

Drought response of <i>Mucuna pruriens</i> (L.) DC. inoculated with ACC deaminase and IAA producing rhizobacteria - Fig 3

<p>Effect of severe water stress (FSTW₁₀) on shoot (A) and root (B) biomass of velvet bean plants grown in soil inoculated with <i>Enterobacter</i> spp. and <i>Bacillus</i> spp., or uninoculated. Values are mean of five plants ± SE, letters indicate significant differences among treatments (<i>P</i> < 0.05).</p