Gene Expression Analysis Suggests Temporal Differential Response to Aluminum in Coffea arabica Cultivars

Abstract

Aluminum (Al) is a limiting factor of crop yields on acidic soils. Ion aluminum (Al3+) acts primarily in plant root system retarding its growth and development, leading to the reduction of lateral roots number, and consequently the decrease of vegetal production. Most of coffee producing areas are located in acidic soils, which have Al3+ contents enough to damage plant development. Despite the advances in the understanding of physiological and genetic mechanisms of Al tolerance/susceptibility, few are known about Al ion action in coffee plants. This report describes the expression analysis of genes related to aluminum stress in germinating seeds of two cultivars of C. arabica (Catuai Amarelo IAC 62 and Icatu Vermelho IAC 4045) when challenged with Al3+. In silico analyses of Brazilian Coffee Genome Project (BCGP) database were used to select genes previously found to be related with Al-stress. The expression profile of these genes in Catuai and Icatu was evaluated through Quantitative PCR (qPCR). Based on our data, we suggest that both analyzed cultivars displays mechanisms of resistance or exclusion, which occurs outside the cell excluding Al3+ assimilation, and mechanisms of tolerance that occurs inside the cell after Al3+ absorption. The major difference is the timing of activation of each mechanism. While Catuai tends to use resistance mechanisms in early stages of stress, Icatu uses tolerance strategies. In late stages, both cultivars seem to display tolerance mechanisms, but Icatu also displays Al-exclusion strategy.