Biology subjects

Acosta-Gamboa, L. M.

Publications and source records attributed to Acosta-Gamboa, L. M..

2 recordsLinked to original sources

bioRxiv2021

Myo-inositol Oxygenase Overexpression Rescues Vitamin C Deficient Arabidopsis (vtc) Mutants

Biosynthesis of O_SCPLOWLC_SCPLOW-ascorbate (AsA) in plants is carried out by a complex metabolic network, which involves O_SCPLOWDC_SCPLOW-mannose/O_SCPLOWLC_SCPLOW-galactose, O_SCPLOWDC_SCPLOW-galacturonate, O_SCPLOWLC_SCPLOW-gulose, and myo-inositol as main precursors. Arabidopsis lines over-expressing enzymes in the myo-inositol pathway have elevated AsA, accumulate more biomass of both aerial and root tissues, and are tolerant to abiotic stresses as shown by manual and digital phenotyping. We crossed myo-inositol oxygenase (MIOX4) over-expressers with two low-vitamin C mutants (vtc1-1 and vtc2-1) encoding enzymes involved in O_SCPLOWDC_SCPLOW-mannose/O_SCPLOWLC_SCPLOW-galactose route. The purpose of developing these crosses was to test MIOX4s ability to restore the low AsA phenotype in mutants, and to assess the contribution of individual biosynthetic pathways to abiotic stress tolerance. We used a powerful high-throughput phenotyping platform for detailed phenotypic characterization of the Arabidopsis crosses with visible, fluorescence, near-infrared and infrared sensors. We combined digital phenotyping with photosynthetic parameters and soil water potential measurements. Our results show that MIOX4 is able to restore the AsA content of the mutants and the restored lines (vtc+MIOX4) show high AsA, enhanced growth rate, accumulate more biomass, and display healthier chlorophyll fluorescence and water content profiles compared to controls. HighlightsConstitutive expression of a myo-inositol oxygenase restored vitamin C deficient (vtc mutants). The restored lines have elevated ascorbate content and are tolerant to abiotic stresses. Under normal and abiotic stress conditions, the restored lines have enhanced biomass and increased water retention.

biochemistry↗

bioRxiv2019

Mechanisms Underlying the Enhanced Biomass and Abiotic Stress Tolerance Phenotypes of an Arabidopsis MIOX Over expresser

Myo-inositol oxygenase (MIOX) is the first enzyme in the inositol route to ascorbate (L-ascorbic acid, AsA, vitamin C). We have previously shown that Arabidopsis plants constitutively expressing MIOX have elevated foliar AsA content and displayed enhanced growth rate, biomass accumulation, and increased tolerance to multiple abiotic stresses. In this work, we used a combination of transcriptomics, chromatography, microscopy, and physiological measurements to gain a deeper understanding of the underlying mechanisms mediating the phenotype of the AtMIOX4 line. Transcritpomic 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 confirmed by assays demonstrating their effect on epidermal cell elongation in the AtMIOX4 over-expresser plants. Additionally, we detected up-regulation of transcripts involved in photosynthesis that was validated by 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 AtMIOX4 line. Interestingly, the high AsA plants also displayed up-regulation 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 levels of auxin and glucose, and enhanced photosynthetic efficiency in combination with up-regulation of abiotic stresses response genes underly the higher growth rate and abiotic stresses tolerance phenotype of the AtMIOX4 over-expressers.

plant biology↗