The products of the two genes formed a complex with efflux transport activity specific for UDP-glucose, of which exogenous addition protected root growth under Al stress. Protein activity of Al-tolerance genes BnALMT1 and BnALMT2 in Brassica was tested in tobacco

cells and Xenopus oocytes and showed that they conferred malate efflux, and transgenic tobacco cells had enhanced tolerance to Al toxicity [143]. The rapid development of molecular markers and QTL mapping of Al tolerance permits MAS for Al tolerance in breeding programs. Traditional Selleck TSA HDAC breeding has benefited from conventional selection based on phenotyping; however, phenotypic selection is reportedly difficult, inefficient and laborious due to its dependence on specific environments [144]. MAS is based on associations between molecular markers and superior alleles of genetic traits of interest. After QTL are validated, tightly-linked markers can be used to detect, transfer and Venetoclax mw accumulate desirable genome regions into superior genotypes, a process that is much faster than phenotypic selection. The major advantages of MAS compared to conventional phenotypic selection are cost-effectiveness, simplicity of selection, time-saving and screening precision [145]. Different types of markers have been developed to trace interesting genes or loci. As discussed in

a previous section, molecular markers including RFLP, AFLP, RAPD, SSR, DArT and SNP have been developed and used in Al-tolerance studies. These have proved efficient in MAS in breeding programs. With increasing 6-phosphogluconolactonase numbers of genes for Al tolerance being identified and sequenced in plants, PCR-based gene-specific markers developed from gene sequencing are preferred in MAS for their easy identification, high polymorphism and good reproducibility [146]. In wheat, Raman et al. [158] developed SSR markers, ALMT1-SSR3a and ALMT1-SSR3b and a CAPS marker from the repetitive InDels and substitution region of the TaALMT1 gene. These PCR-based markers co-segregating with the tolerance locus should be efficient tools for MAS [147]. In barley, one gene-specific marker, HvMATE-21indel,

was developed from the tolerance gene HvMATE. The marker increased the explained phenotypic variation compared with the other SSR markers. It can also be used for selecting the tolerance gene from multiple tolerance sources [148]. With additional and different types of molecular markers being developed for Al tolerance, breeding programs could be accelerated by using these markers in MAS [78]. Transgenic methods are very efficient for validating gene function in Al-tolerance studies. The first report on a transgenic approach to increasing Al tolerance in plants was in 1997 when De La Fuente et al. [149] reported that an overexpressed citrate synthase gene enhanced citrate efflux and led to improved root Al tolerance in transgenic tobacco.