Molecular breeding for improving aluminium resistance in wheat.

This chapter aims at describing the main physiological mechanisms associated with aluminium (Al) resistance in wheat and how the research about these mechanisms has evolved to its current status. Practical aspects of phenotyping and using the molecular basis to increase Al resistance, which can be easily introduced in breeding programmes, are detailed. This chapter discusses the reliability of methods to screen root growth under Al stress, the allelic variation of genes associated with the main Al resistance mechanism in wheat, the quantitative trait loci and genomic regions that might contain minor Al tolerance genes, the use of wheat wild relatives, the uncertainties of developing transgenic wheat for greater Al resistance and the development of Al-resistant lines of durum wheat (Triticum turgidum subsp. durum).

The varied functions of aluminium-activated malate transporters–much more than aluminium resistance

The ALMT (aluminium-activated malate transporter) family comprises a functionally diverse but structurally similar group of ion channels. They are found ubiquitously in plant species, expressed throughout different tissues, and located in either the plasma membrane or tonoplast. The first family member identified was TaALMT1, discovered in wheat root tips, which was found to be involved in aluminium resistance by means of malate exudation into the soil. However, since this discovery other family members have been shown to have many other functions such as roles in stomatal opening, general anionic homoeostasis, and in economically valuable traits such as fruit flavour. Recent evidence has also shown that ALMT proteins can act as key molecular actors in GABA (γ-aminobutyric acid) signalling, the first evidence that GABA can act as a signal transducer in plants.