Root malate efflux and expression of TaALMT1 in Serbian winter wheat cultivars differing in Al tolerance

Aluminium (Al) toxicity in acid soils is a global problem. Here, we investigated Al tolerance in high yielding winter wheat (Triticum aestivum L.) cultivars bred in Serbia. The common relative mot length (RRL) test for Al tolerance, and both physiological (malate efflux) and molecular (Aluminium-Activated Malate Transporter 1 [TaALMT1] expression) approaches were used for this characterization. Both moderately Al-tolerant cvs. Ljiljana and Arabeska showed significantly higher malate efflux rate from the root tips in comparison to moderately Al-sensitive cv. Pobeda and followed the RRL pattern. Irrespectively of Al supply, moderately Al-tolerant cultivars showed significantly higher relative TaALMT1 expression than the Al-sensitive ones. A considerably high level of Al tolerance was found in cv. Ljiljana, which showed the highest Al-induced malate efflux along with the highest constitutive expression level of TaALMT1 transcripts. Our results also demonstrate that Al tolerance is based on a constitutive trait of high TaALMT1 expression and malate efflux in wheat roots, resulting in a decrease in root length reduction