Interaction of aluminium and drought stress on root growth and crop yield on acid soils

Abstract

Background Aluminium (Al) toxicity and drought stress are two major constraints for crop production in the world, particularly in the tropics. The variation in rainfall distribution and longer dry spells in much of the tropics during the main growing period of crops are becoming increasingly important yield-limiting factors with the global climate change. As a result, crop genotypes that are tolerant of both drought and Al toxicity need to be developed. Scope The present review mainly focuses on the interaction of Al and drought on root development, crop growth and yield on acid soils. It summarizes evidence from our own studies and other published/related work, and provides novel insights into the breeding for the adaptation to these combined abiotic stresses. The primary symptom of Al phytotoxicity is the inhibition of root growth. The impeded root system will restrict the roots for exploring the acid subsoil to absorb water and nutrients which is particularly important under condition of low soil moisture in the surface soil under drought. Whereas drought primarily affects shoot growth, effects of phytotoxic Al on shoot growth are mostly secondary effects that are induced by Al affecting root growth and function, while under drought stress root growth may even be promoted. Much progress has recently been made in the understanding of the physiology and molecular biology of the interaction between Al toxicity and drought stress in common bean (Phaseolus vulgaris L.) in hydroponics and in an Al-toxic soil. Conclusions Crops growing on acid soils yield less than their potential because of the poorly developed root system that limits nutrient and water uptake. Breeding for drought resistance must be combined with Al resistance, to assure that drought resistance is expressed adequately in crops grown on soils with acid Al-toxic subsoils.

TAA1-Regulated Local Auxin Biosynthesis in the Root-Apex Transition Zone Mediates the Aluminum-Induced Inhibition of Root Growth inArabidopsis

“…The correlation between the RNAseq and qRT-PCR data was highly significant (r 2 = 0.85, P < 0.001) (Supplemental Figure 11D). The rapid binding of Al to the cell wall matrix is expected to alter the properties of the cell wall and thereby affect root growth (Tabuchi and Matsumoto, 2001;Ma et al, 2004;Horst et al, 2010;Yang et al, 2013). Several genes related to cell wall structure and composition, including those encoding xyloglucanases, endotransglycosylases, polygalacturonases, and glycosyl transferases, have been identified as being involved in the regulation of Al tolerance or the Alinduced inhibition of root growth (Kumari et al, 2008;Maron et al, 2008;Tsutsui et al, 2012;Zhu et al, 2012).…”

Last-Century Increases in Intrinsic Water-Use Efficiency of Grassland Communities Have Occurred over a Wide Range of Vegetation Composition, Nutrient Inputs, and Soil pH

“…High aluminum concentrations may have exacerbated the effect of climatic variability by causing greater soil moisture deficits on the acidic plots; aluminum toxicity is known to inhibit root growth (Kochian, 1995;Horst et al, 2010), leading to reduced root length density and shallower rooting depth (Jentschke et al, 2001;Tang et al, 2001) in a variety of species. Physiological relationships between aluminum toxicity, impeded root growth, and drought sensitivity of plants are well established (Yang et al, 2013). Also, Dodd et al (1994b) suggested that the large yield variability of the species-poor, acidic plots on the PGE were related (at least in part) to soil moisture deficits.…”

Root traits and their potential links to plant ideotypes to improve drought resistance in common bean

“…Phenotypic evaluations of root traits in common bean under drought stress have shown the importance of different rooting patterns, including deep rooting which allows access to water from deeper soil layers (Sponchiado et al 1989;White and Castillo 1992;Lynch and Ho 2005;Polania et al 2009Polania et al , 2012Beebe et al 2013Beebe et al , 2014Rao 2014;Burridge et al 2016). Different ideotypes of root system have been proposed for better crop adaptation to individual and combined abiotic stress conditions (Yang et al 2013;Rao et al 2016). One of the root ideotypes proposed to optimize water and N acquisition is the ''steep, cheap and deep -SCD'' (Lynch 2013).…”