Hormonal regulation of source - sink relations to maintain crop productivity under salinity: a case study of root-to-shoot signalling in tomato

Abstract

Salinity decreases crop yield first by reducing growth of assimilate-consuming sink organs and, second, by decreasing assimilate production in photosynthetically active source tissues. Although much work has focussed on controlling the accumulation of toxic ions (mainly Na+ and Cl–), the search for primary growth limiting factor(s) continues. The root, by sensing environmental constraints of the soil, may influence root-to-shoot signalling to control shoot growth and physiology, and ultimately agricultural productivity. Hormonal signals, such as cytokinins, ABA, the ethylene precursor 1-aminocyclopropane-1-carboxylic acid and the auxin indole-3-acetic acid may coordinate assimilate production and usage in competing sinks (biomass partitioning). Hormonal regulation of source–sink relations during the osmotic phase of salinity (independent of specific ions) affects whole-plant energy availability to prolong the maintenance of growth, root function and ion homeostasis, and could be critical to delay the accumulation of Na+ or any other ion to toxic levels. This viewpoint emphasises that simultaneously maintaining growth and delaying early leaf senescence is necessary to increase crop yield in salt-affected soils.

Agricultural uses of plant biostimulants

“…This effect could be responsible for improved plant water status, chlorophyll concentration, and photosynthetic capacity by increasing photochemical efficiency (Sheng et al 2008). In a manner similar to drought conditions, plant growth under saline stress may be regulated via changes in phytohormone concentrations (Pérez-Alfocea et al 2010). Hence the capacity of microbial inoculants to induce changes in phytohormones could be one of the mechanisms involved in enhancing plant tolerance to salinity (Dodd and Pérez-Alfocea 2012;Dodd et al 2010).…”

Salinity Stress and Arbuscular Mycorrhizal Symbiosis in Plants

“…Eventually, the accumulation of carbohydrate in the sink associated with salt stress represents the first limiting step for salt tolerance and can be restored and enhanced in mycorrhizal plants (Perez-Alfocea et al 2010;Dodd and Perez-Alfocea 2012). High sugar content in maize plants due to AM symbiosis was observed under salt stress by Feng et al (2002).…”

The Effectiveness of Different Rootstocks for Improving Yield and Growth of Cucumber Cultivated Hydroponically in a Greenhouse

“…In the other scion/rootstock combinations, no clear relation was found between root vigor and scion response. In this regard, plant growth and production could be influenced by hormonal signals from the rootstock that could alter shoot physiology [5,14]. Cucurbit plant stems usually secrete xylem sap when decapitated, which is greatly influenced by the rootstock and contains high concentrations of minerals and plant hormones.…”