Biochemical, physiological and genetic analysis of aluminum tolerance of different rye species

Abstract Aluminum (Al) toxicity is the major limitation for crop productivity in acid soils which are widespread all over the world. Plant species differ in their responses to this abiotic stress having developed resistance mechanisms to detoxify and tolerate Al both internally and externally. Rye ( Secale cereale L.) is one of the most Al-tolerant cereal with a valuable genetic background for breeding purposes. Wild relatives ( Secale spp.) have great importance once they can provide new sources of genes related to this trait. Different cellular disorders possibly related to Al tolerance/toxicity were observed through histochemical root staining methods in cultivated and wild ryes and a correlation was found. Moreover, expression studies of seven candidate Al-tolerance genes ( ScALMT1 , ScMATE2 , ScSTOP1 , ScMDH1 , ScMDH2 , ScCu/ZnSOD and ScMnSOD ) were performed in roots and shoots of five wild ryes. All genes seems to have an active contribution on Al resistance mechanisms of these ryes, however, ScALMT1 and ScMATE2 genes clearly have a key role in the Al-tolerance increment. Al tolerance in Secale genus seems to be a genetically complex trait where different resistance mechanisms coexist, due to several genes whose cumulative effects improves the ability to withstand Al phytotoxicity.