Deciphering the major metabolic pathways associated with aluminum tolerance in popcorn roots using label-free quantitative proteomics

Aluminum toxicity is one of the most important abiotic stresses that affects crop production worldwide. The soluble form (Al3+) inhibits root growth, altering water and nutrients uptake reducing the plant growth and development. Under a long term of Al3+ exposure, plants can activate several tolerance mechanisms and, to date, there are no reports of large-scale proteomic data of maize in response to this ion. To investigate the post-transcriptional regulation in response to Al toxicity, we performed a label-free quantitative proteomics for comparative analysis of two Al-contrasting popcorn inbred lines and an Al-tolerant commercial hybrid during 72 h under Al-stress. A total of 489 differentially accumulated proteins (DAPs) were identified in the Al-sensitive inbred line, 491 in the Al-tolerant inbred line, and 277 in the commercial hybrid. Among then, 120 DAPs were co-expressed in both Al tolerant genotypes. Bioinformatics analysis indicated that starch and sucrose metabolism, glycolysis/gluconeogenesis, and carbohydrate metabolism were significant biochemical process regulated in response to Al toxicity. The up-accumulation of sucrose synthase and the increased of sucrose content and starch degradation suggest that these components may be enhance popcorn tolerance to Al stress. The up-accumulation of citrate synthase suggests a key role of this enzyme in the detoxification process in the Al-tolerant inbred line. The integration of transcriptomic and proteomic data indicated that Al tolerance response presents a complex regulatory network into the transcription and translation dynamics of popcorn roots development.