Initial root length in wheat is highly correlated with acid soil tolerance in the field

Jorge Fernando Pereira

doi:10.1590/1678-992x-2016-0422

Abstract

ABSTRACT: In acid soils, toxic aluminum ions inhibit plant root growth. In order to discriminate aluminum (Al) tolerance, trustful screening techniques are required. In this study, 20 wheat cultivars, showing different levels of Al tolerance, were evaluated in a short-term soil experiment to access their relative root length (RRL). Moreover, the alleles of two important genes (TaALMT1 and TaMATE1B) for Al tolerance in wheat were discriminated. Both of these genes encode membrane transporters responsible for the efflux of organic acids by the root apices that are thought to confer tolerance by chelating Al. Genotypes showing TaALMT1 alleles V and VI and an insertion at the TaMATE1B promoter were among the ones showing greater RRL. Mechanisms of Al tolerance, which are not associated with organic acid efflux, can be potentially present in two cultivars showing greater RRL among the ones carrying inferior TaALMT1 and TaMATE1B alleles. The RRL data were highly correlated with wheat performance in acid soil at three developmental stages, tillering (r = −0.93, p < 0.001), silking (r = −0.91, p < 0.001) and maturation (r = −0.90, p < 0.001), as well as with the classification index of aluminum toxicity in the field (r = −0.92, p < 0.001). Since the RRL was obtained after only six days of growth and it is highly correlated with plant performance in acid soil under field conditions, the short-term experiment detailed here is an efficient and rapid method for reliable screening of wheat Al tolerance.

Highlights

Plants can come across toxic aluminum (Al) ions, especially the trivalent cation (Al3+), when grown on acid soils
Since the relative root length (RRL) was obtained after only six days of growth and it is highly correlated with plant performance in acid soil under field conditions, the short-term experiment detailed here is an efficient and rapid method for reliable screening of wheat Al tolerance
The lowest relative root length (RRL) was observed in three genotypes previously characterized as sensitive (Tiacena 1, Embrapa 10 and Anahuac 75) and the highest RRL were detected in two genotypes classified as tolerant (BH 1146 and C33)

Summary

Introduction

Plants can come across toxic aluminum (Al) ions, especially the trivalent cation (Al3+), when grown on acid soils. Polymorphisms at the promoter region of these genes are associated with the level of gene expression, organic acid efflux and Al tolerance (Aguilera et al, 2016; Pereira et al, 2015; Raman et al, 2008; Sasaki et al, 2006; Tovkach et al, 2013). Considering the importance of describing Al tolerance screening methods that are reliable, this study aimed to access the relative root length of wheat genotypes contrasting for acid soil tolerance using a short-term soil experiment and to correlate the initial root length with plant performance in acid soil under field conditions. An association between the initial root length and the TaALMT1 and TaMATE1B alleles was sought. This association can reveal the putative additive effect of these genes or if other Al tolerance mechanisms can be found

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