Transcriptomics study of high ascorbate Arabidopsis

High L- ascorbate Arabidopsis have enhanced biomass and tolerant to abiotic stresses. The molecular mechanism underlying this phenomena is still unknown. In silico and RT-qPCR analysis revealed increased expression of genes involved in auxin synthesis, hydrolysis, transport, and metabolism, which are supported by elevated auxin levels both in-vitro and in-vivo, and by assays demonstrating their effect on epidermal cell elongation in the AtMIOX4 over-expresser. Additionally, we detected upregulation of transcripts involved in photosynthesis and in support to this finding, the transgenic plants displayed increased efficiency of the photosystem II and proton motive force. We also found increased expression of amylase leading to higher intracellular glucose levels. Multiple gene families conferring plants tolerance to cold, water limitation, and heat stresses were found to be elevated in the MIOX4 line. Interestingly, the high AsA plants also displayed upregulation of transcripts and hormones involved in defense including jasmonates, defensin, glucosinolates, and transcription factors that are known to be important for biotic stress tolerance. These results overall indicate that elevated auxin and glucose, enhanced phosynthetic efficiency in combination with up-regulation of abiotic stresses response genes are some of the reasons that explain the higher growth rate and abiotic stresses tolerance phenotype of the AtMIOX4 over-expressers.