Research on function and structure of plant-specific malate transporters
Aluminum (Al) ion is a major inhibitory factor of plant growth in acidic soils which comprise almost 40% of the world arable land. Toxic Al cations (Al3+) rapidly inhibit root growth and prevent subsequent uptake of water and nutrients. The mechanisms of Al toxicity and tolerance are analyzing using a cultured cell system and whole plants. Especially Al-tolerance mechanism, wheat ALMT1 gene encoding Al-activated malate transporter was found by our group, and demonstrated as Al-tolerant as well as acidic-soil tolerant gene, for the first time in crops. In addition, since the ALMT gene and its homologues have been found only in plants, the diversity of physiological functions for individual ALMT genes was elucidated as recent studies. The molecular details of the structure and functions and the expression mechanisms of these transporters are now studied.
A gene encoding aluminum (Al)-activated malate transporter (ALMT1) regulates Al tolerance of wheat.
It was previously shown that Al tolerance in wheat (Triticum aestivum L.) is correlated with the Al-activated efflux of malate which chelates and detoxifies Al cations around root apices. To isolate the gene involved in this mechanism, Sasaki et al. (2004, Plant J.) examined a pair of near-isogenic wheat lines that differed in Al tolerance at a single genetic locus, and found a gene which shows greater expression in the root apices of ET8 (the Al-tolerant line) than that of ES8 (the sensitive line), as depicted in the photograph. The gene is named ALMT1 which encodes a novel transporter protein facilitating the Al-activated efflux of malate and is a major Al-tolerant gene of wheat.