Liming can decrease legume crop yield and leaf gas exchange by enhancing root to shoot ABA signalling

Abstract

HighlightThis paper describes a novel mechanistic understanding of how recommended rates of liming to manage soil pH may cause reduced gas exchange and growth in legumes.

Long-distance ABA transport can mediate distal tissue responses by affecting local ABA concentrations

“…Contrary to previous studies where limited P increased [ABA] leaf (Jeschke et al ; Rothwell et al ), we found that low P decreased [ABA] leaf and [ABA] xylem in all graft combinations (Figure ), which may result from changes in ABA biosynthesis, degradation, or long‐distance transport (Jeschke et al ; Peuke ). The decreased root hydraulic conductance of P‐deprived plants (Radin and Matthews ) should decrease leaf turgor, thereby stimulating leaf ABA accumulation, but no change in Ψ leaf was detected in our study (Figure A).…”

“…Under both P treatments, the higher g s (and lower Ψ leaf ) of the flc self‐grafts suggests that g s regulates Ψ leaf (Figure A), as previously reported for these graft combinations (Dodd et al ) and for reciprocally grafted WT and strigolactone‐deficient tomato plants (Visentin et al ). Foliar ABA accumulation was previously reported to correlate with low‐P‐induced stomatal closure (Radin ; Rothwell et al ). Although [ABA] leaf determined the maximal g s (Figure C), we found that low P decreased g s and [ABA] leaf in all graft combinations involving flc as either the rootstock or the scion, suggesting that other phytohormones (Martínez‐Andújar et al ) mediate stomatal responses to P status.…”

“…Direct ABA‐mediated growth maintenance appears to be more important than any possible stomatal limitation of photosynthesis induced by P deprivation (Fujita et al ; Rothwell et al ). Although decreased g s correlated with suboptimal plant P concentrations under well‐watered conditions (Biddinger et al ; Rothwell et al ), we found that g s was independent of P leaf (Figure B).…”

“…Direct ABA‐mediated growth maintenance appears to be more important than any possible stomatal limitation of photosynthesis induced by P deprivation (Fujita et al ; Rothwell et al ). Although decreased g s correlated with suboptimal plant P concentrations under well‐watered conditions (Biddinger et al ; Rothwell et al ), we found that g s was independent of P leaf (Figure B). Under both P treatments, the higher g s (and lower Ψ leaf ) of the flc self‐grafts suggests that g s regulates Ψ leaf (Figure A), as previously reported for these graft combinations (Dodd et al ) and for reciprocally grafted WT and strigolactone‐deficient tomato plants (Visentin et al ).…”

Rhizosphere bacteria containing 1-aminocyclopropane-1- carboxylate deaminase increase growth and photosynthesis of pea plants under salt stress by limiting Na+ accumulation

“…Attenuation of liming-induced stomatal closure in the ABA-deficient wilty pea mutant (Rothwell et al 2015) suggests an important role for ABA in mediating stomatal responses of pea to changes in rhizosphere elemental status, requiring further studies in salinised plants. Nevertheless, distinguishing the relative importance of phytohormonal and nutritional effects on stomatal closure can be challenging (Rothwell et al 2015). Although increased shoot K + : Na + ratio in response to ACCdeaminase containing PGPR has been demonstrated previously .…”