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Background <p>Functional investigation of individual <i>Rhizobium rhizogenes</i> oncogene contributes to a deeper understanding of the mechanisms underlying <i>R. rhizogenes</i>-plant transformation, which holds the potential of enhancing plants’ abiotic stress resistance. The <i>root oncogenic locus</i> (<i>rol</i>) <i>B</i> gene, a key oncogene of <i>R. rhizogenes</i>, was reported to participate in abiotic stress resistance in transformed plants. Yet, the underlying mechanisms remain largely elusive. This study investigated Arabidopsis overexpressing A4-<i>rolB</i> (<i>rolB</i>-OX) for phenotypic modifications and short-term osmotic stress resistance.</p> Results <p>Data showed that A4-<i>rolB</i> induced pronounced dwarfing phenotypes and weakened root growth in <i>rolB</i>-OX as shown by its compact growth and significantly decreased root length and root surface area (59% and 63% of wild type Col-0, respectively) under normal growth conditions. Under polyethylene glycol 6000 (PEG) 10% (w/v)-induced osmotic stress, <i>rolB</i>-OX exhibited enhanced resistance to osmotic stress compared with Col-0, as exemplified by less severe leaf wilting, increased total antioxidant capacity (TAC), and a better recovery of stomatal conductance after PEG treatment. Moreover, A4-<i>rolB</i> mediated enhancement in abscisic acid (ABA) levels under well-watered conditions, which may have facilitated stress resistance of <i>rolB</i>-OX under PEG exposure, probably through inducing TAC. Furthermore, after PEG stress, <i>rolB</i>-OX exhibited dramatically up-regulated (3.3–5.7-fold of Col-0) transcript levels of genes encoding plasma membrane intrinsic proteins (<i>PIPs</i>) (i.e., <i>PIP2;5</i> and <i>PIP2;7</i>), which are correlated with an improved plant hydraulic conductivity.</p> Conclusions <p>This study reports an enhanced osmotic stress resistance in <i>rolB</i>-OX, which could be attributed to A4-<i>rolB</i>-mediated increase in leaf ABA levels and TAC and improved stomatal regulation. Furthermore, the association between ABA and TAC, and its effect on the osmotic stress resistance caused by <i>rolB</i>, was thoroughly discussed in this study. These findings reveal novel physiological effects of A4-<i>rolB</i> on plant abiotic stress resistance.</p>

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Overexpression of Rhizobium rhizogenes A4-rolB enhances osmotic stress resistance in Arabidopsis

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年5月27日

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  • Xuefei Chen,
  • Bruno Trevenzoli Favero,
  • Fulai Liu,
  • Henrik Lütken

摘要

Background

Functional investigation of individual Rhizobium rhizogenes oncogene contributes to a deeper understanding of the mechanisms underlying R. rhizogenes-plant transformation, which holds the potential of enhancing plants’ abiotic stress resistance. The root oncogenic locus (rol) B gene, a key oncogene of R. rhizogenes, was reported to participate in abiotic stress resistance in transformed plants. Yet, the underlying mechanisms remain largely elusive. This study investigated Arabidopsis overexpressing A4-rolB (rolB-OX) for phenotypic modifications and short-term osmotic stress resistance.

Results

Data showed that A4-rolB induced pronounced dwarfing phenotypes and weakened root growth in rolB-OX as shown by its compact growth and significantly decreased root length and root surface area (59% and 63% of wild type Col-0, respectively) under normal growth conditions. Under polyethylene glycol 6000 (PEG) 10% (w/v)-induced osmotic stress, rolB-OX exhibited enhanced resistance to osmotic stress compared with Col-0, as exemplified by less severe leaf wilting, increased total antioxidant capacity (TAC), and a better recovery of stomatal conductance after PEG treatment. Moreover, A4-rolB mediated enhancement in abscisic acid (ABA) levels under well-watered conditions, which may have facilitated stress resistance of rolB-OX under PEG exposure, probably through inducing TAC. Furthermore, after PEG stress, rolB-OX exhibited dramatically up-regulated (3.3–5.7-fold of Col-0) transcript levels of genes encoding plasma membrane intrinsic proteins (PIPs) (i.e., PIP2;5 and PIP2;7), which are correlated with an improved plant hydraulic conductivity.

Conclusions

This study reports an enhanced osmotic stress resistance in rolB-OX, which could be attributed to A4-rolB-mediated increase in leaf ABA levels and TAC and improved stomatal regulation. Furthermore, the association between ABA and TAC, and its effect on the osmotic stress resistance caused by rolB, was thoroughly discussed in this study. These findings reveal novel physiological effects of A4-rolB on plant abiotic stress resistance.