Atmospheric CO₂ enrichment and drought stress modify root exudation of barley

Abstract

Rising CO concentrations associated with drought stress is likely to influence not only aboveground growth, but also belowground plant processes. Little is known about root exudation being influenced by elements of climate change. Therefore, this study wanted to clarify whether barley root exudation responds to drought and CO enrichment and whether this reaction differs between an old and a recently released malting barley cultivar. Barley plants were grown in pots filled with sand in controlled climate chambers at ambient (380 ppm) or elevated (550 ppm) atmospheric [CO ] and a normal or reduced water supply. Root exudation patterns were examined at the stem elongation growth stage and when the inflorescences emerged. At both dates, root exudates were analyzed for different compounds such as total free amino acids, proline, potassium, and some phytohormones. Elevated [CO ] decreased the concentrations in root exudates of some compounds such as total free amino acids, proline, and abscisic acid. Moreover, reduced water supply increased proline, potassium, electric conductivity, and hormone concentrations. In general, the modern cultivar showed higher concentrations of proline and abscisic acid than the old one, but the cultivars responded differentially under elevated CO . Plant developmental stage had also an impact on the root exudation patterns of barley. Generally, we observed significant effects of CO enrichment, watering levels, and, to a lesser extent, cultivar on root exudation. However, we did not find any mitigation of the adverse effects of drought by elevated CO . Understanding the multitude of relationships within the rhizosphere is an important aspect that has to be taken into consideration in the context of crop performance and carbon balance under conditions of climate change.

Rhizosphere pseudomonads as probiotics improving plant health

“…These findings are interesting with respect to the discussion that plants or microbes engineered to overproduce trehalose survive better under drought stress (Glick, ). Changes in the composition and amounts of metabolites, such as organic acids, released in root exudates from drought‐affected plants probably contribute to changes in the root microbiome and function (Bouskill et al ., ; Calvo et al ., ; Naylor and Coleman‐Derr, ).…”

Elevated CO2 alters the structure of the bacterial community assimilating plant‐derived carbon in the rhizosphere of soya bean

“…This C efflux contributes to 4‐ to 20‐fold increases in microbial biomass and up to 3‐fold increases in the rates of decomposition of organic substrates in the rhizosphere compared to the bulk soil (Blagodatskaya, Blagodatsky, Anderson, & Kuzyakov, ). Plant roots release up to 20–30% of total photosynthetically‐fixed C into the rhizosphere (Calvo et al, ), which is metabolized by microorganisms and incorporated into soil C pools. However, elevated atmospheric CO 2 (eCO 2 ) concentration not only increases the quantity of rhizodeposits but also alters their quality in many plant species (Jin et al, ).…”

Different ways to die in a changing world: Consequences of climate change for tree species performance and survival through an ecophysiological perspective

“…In view of this increase in performance and productivity promoted by high [CO 2 ], even in the presence of abiotic stresses, should we really be concerned about the dynamics of the distribution and survival of forest species under a climate change scenario? The answer to this question is extremely complex because the beneficial effects of high [CO 2 ] found in some studies (Drake et al, 2011;Idso & Kimbal, 1997;Oliveira et al, 2016;Pérez-Jiménez, Hernández-Munuera, Piñero, López-Ortega, & del Amor, 2018;Radoglou & Jarvis, 1990;Rodrigues et al, 2016;Roy et al, 2016;Swann et al, 2016;Yu et al, 2014) are in direct contrast to the results of several other reports (Calvo et al, 2017;Clark, Clark, & Oberbauer, 2010;Faralli et al, 2017;Feeley, Joseph Wright, Nur Supardi, Kassim, & Davies, 2007;Voelker et al, 2017).…”