Role of ascorbic acid in modifying root architecture, growth, and productivity of Arabidopsis thaliana
Noura Masseh Ellya Kka
Deakin University, Australia
: J Plant Physiol Pathol
Abstract
Ascorbic acid (AsA) participates in several aspects of plant growth, development, and productivity. Under optimum growth conditions, plants accumulate variable amounts of AsA in different organs. This project has examined, in Arabidopsis thaliana, the effect of AsA on growth and seed production through analysis of morphological and physiological parameters. The highest levels of AsA were found in flowering buds, premature siliques, leaves, and stems, respectively. In addition, the AsA level correlated positively with concentrations of indole acetic acid (IAA) but inversely with salicylic acid (SA) concentrations. Plants synthesise AsA through six different pathways and primarily through the galactose pathway. A mutant defective in production of GDP-mannose pyrophosphorylase, vtc1-1, had significantly reduced growth parameters such as root growth rate, root length, number of leaves, leaf area and plant height compared with vtc5-1 (defective in GDP-L-galactose phosphorylase production), dhar1 (defective in mitochondrial dehydroascorbate reductase) apx1 (defective in cytosolic ascorbate peroxidase) and the Col-0 wild type background. The role of AsA as a signal for the promotion of cell expansion was verified in embryonic root cap studies. In addition, AsA promoted cell division by rapid stimulation of differentiation in surrounding cells of the root quiescent centre in Col-0 compared with vtc1-1. A lack of AsA increased the intensity of hydrogen peroxide production in roots and also increased the number of secondary roots. Surprisingly the number of flowers and siliques per plant, the number of seeds per silique and seed size were also all affected in vtc1-1, which indicates a key role for AsA in plants.
Biography
nmkka@deakin.edu.auE-mail: nmkka@deakin.edu.au
