Global Transcriptome Analysis of Al-Induced Genes in an Al-Accumulating Species, Common Buckwheat (Fagopyrum esculentum Moench)

Buckwheat (Fagopyrum esculentum Moench) is a species with high aluminum (Al) tolerance and accumulation. Although the physiological mechanisms for external and internal detoxification of Al have been well studied, the molecular mechanisms responsible are poorly understood. Here, we conducted a genome-wide transcriptome analysis of Al-responsive genes in the roots and leaves using RNA sequencing (RNA-Seq) technology. RNA-Seq generated reads ranging from 56 x 10(6) to 93 x 10(6). A total of 148,734 transcript contigs with an average length of 1,014 bp were assembled, generating 84,516 unigenes. Among them, 31,730 and 23,853 unigenes were annotated, respectively, in the NCBI plant database and TAIR database for Arabidopsis. Of the annotated genes, 4,067 genes in the roots and 2,663 genes in the leaves were up-regulated (>2-fold) by Al exposure, while 2,456 genes in the roots and 2,426 genes in the leaves were down-regulated (<2-fold) A few STOP1/ART1 (SENSITIVE TO PROTON RHIZOTOXICITY1/AL RESISTANCE TRANSCRIPTION FACTOR1)-regulated gene homologs including FeSTAR1, FeALS3 (ALUMINUM SENSITIVE3), FeALS1 (ALUMINUM SENSITIVE1), FeMATE1 and FeMATE2 (MULTIDRUG AND TOXIC COMPOUND EXTRUSION1 and 2) were also up-regulated in buckwheat, indicating some common Al tolerance mechanism across the species, although most STOP1/ART1-regulated gene homologs were not changed. Most genes involved in citric and oxalic acid biosynthesis were not significantly altered. Some transporter genes were highly expressed in the roots and leaves and responded to Al stress, implicating their role in Al tolerance and accumulation. Overall, our data provide a platform for further characterizing the functions of genes involved in Al tolerance and accumulation in buckwheat.