Root adaptive responses to aluminum-toxicity revealed by RNA-Seq in two citrus species with contrasting aluminum tolerance
Background: Limited data are available on aluminum (Al)-toxicity-induced alterations of gene profiles in woody plants. Seedlings of Al-tolerant Citrus sinensis and Al-intolerant Citrus grandis were fertigated with nutrient solution containing 0 and 1.0 mM AlCl3•6H2O. Thereafter, we investigated the Al-toxicity-induced alterations of transcriptomics in roots by RNA-Seq. Results: Using RNA-seq, we isolated 1293 (990) up- and 1377 (915) downregulated genes from Al-treated C. grandis (C. sinensis) roots. Clearly, gene expression was less affected by Al-toxicity in C. sinensis roots than in C. grandis ones. Several Al-toxicity-responsive genes homologous to known Al-tolerance genes: Al-activated malate transporter, multidrug and toxic compound extrusion (MATE), IRON REGULATED/ferroportin 1, sensitive to proton rhizotoxicity 1 and monogalactosyldiacylglycerol synthase were identified in citrus roots. However, Al-induced upregulation of all these genes was stronger in C. grandis roots than in C. sinensis ones except for MATEs. Genes related to signal transduction, and sulfur transport and metabolism might also play a role in the higher Al-tolerance of C. sinensis. Conclusions: This is the first comparative investigation of transcriptomic responses in Al-treated citrus roots. There were common and unique mechanisms for citrus Al-tolerance. These results provide a platform for further investigating the roles of genes possibly responsible for citrus Al-tolerance. Overall design: Examination of mRNA levels in control and Al-treatment roots of C. grandis and C. sinensis with two biological replicates were generated by deep sequencing, using Illumina HiSeq 2000 device.
External Link: /pubmed:28337215