6 - Transporters regulating aluminum uptake, accumulation, and toxicity in plants

Abstract

Aluminum (Al) can increase tolerance against abiotic stress, like some other beneficial elements, and provides resistance against biotic stresses. In plants, the Al tolerance mechanism is due to Al active organic acids (OA) secreted from the root tips. Depending on the plant, generally, OAs participating in the detoxification process of Al are malate, citrate, and oxalate in wheat and Arabidopsis malate, in maize citrate, and in buckwheat and tomato oxalate. The Al-activated malate transporter (ALMT) is an omnipresent family, with sequenced genomes all over the plant kingdom. The family name originated after the first identified member involved in stimulating wheat tolerance against Al. In Arabidopsis, AtALMT1 (malate channel) is significant for Al resistance expressed at the plasma membrane (PM) (epidermal cells) of the root tip. In maize, ZmALMT1 is critical for Al resistance. In Arabidopsis, NIP1;2 is a PM-localized transporter mediating Al uptake, translocation, and tolerance.