Overexpression of Mitochondrial Citrate Synthase in Arabidopsis thaliana Improved Growth on a Phosphorus-Limited Soil

Abstract

The gene for mitochondrial citrate synthase (CS) was isolated from Daucus carota (DcCS) and introduced into Arabidopsis thaliana (strain WS) using Agrobacterium tumefaciens-mediated transformation. Characteristics of citrate excretion were compared between T3 transgenic plants, which were derived from the initial transgenic plants by self-fertilization and homozygous for DcCS, and the control plants that had no DcCS. The highest CS activity 0.78 micromol protein min(-1) exhibited by the transgenic plants was about threefold greater than that found in the control plants (0.23-0.28 micromol protein min(-1)). Western analysis of the transgenic plants showed two CS signals corresponding to signals obtained from both D. carota and A. thaliana. Thus, it appears that the CS polypeptides by ectopic expression of DcCS were processed into the mature form and localized in the mitochondria of A. thaliana. The signal corresponding to the mature form of DcCS were greater in the transgenic plants having higher levels of CS activity. When the transgenic plants were grown in Al-phosphate media, a correlation between the levels of CS activity and the amounts of citrate excreted into the medium. The highest value (5.1 nmol per plant) was about 2.5-fold greater than that from control plants (1.9 nmol per plant). Both growth and P accumulation were greater in transgenic plants with high CS activity than that in control plants when they were grown on an acid soil where the availability of phosphate was low due to the formation of Al-phosphate. It appears that the overexpression of CS in A. thaliana improves the growth in phosphorous limited soil as a result of enhanced citrate excretion from the roots.

Systemic Activin signaling independently regulates sugar homeostasis, cellular metabolism, and pH balance in Drosophila melanogaster

“…We observe that loss of Daw leads to significant increase in the expression of multiple TCA cycle enzymes in the larval FB, leading to the possibility that overproduction of TCA cycle intermediates is caused by an increased TCA cycle activity. Similar effects of TCA cycle enzyme overexpression on overproduction of metabolic acids have been documented before (18)(19)(20). For instance, overexpression of mitochondrial malate dehydrogenase has been shown to increase both production and exudation of citrate, oxalate, malate, succinate, and acetate by up to 4.2-fold and 7.1-fold, respectively, in Alfalfa root tips (20).…”

“…For instance, overexpression of mitochondrial malate dehydrogenase has been shown to increase both production and exudation of citrate, oxalate, malate, succinate, and acetate by up to 4.2-fold and 7.1-fold, respectively, in Alfalfa root tips (20). Similarly, overexpression of citrate synthase has been documented to increase citrate production in both Saccharomyces cerevisiae and Arabidopsis (18,19). We checked whether a similar effect could be seen in Drosophila larvae by overexpressing Drosophila mitochondrial malate dehydrogenase (mdh2) using a tub-Gal4 driver.…”

Alteration in the gene expression ofGlehnia littoralisseedlings exposed to culture filtrate ofPenicillium citrinumKACC43900

“…The uniquely expressed, ent-kaur 16-ene synthase affect plant growth by catalyzing the synthesis of ent-kaur 16-ene, a gibberellin biosynthesis precursor, from ent-copalyl diphosphate (Xu et al 2007), thus indicating the presence of GAs inducing secondary metabolites in the fungal CF. Citrate synthase like protein was expressed uniquely in the treated plants, a reportedly GAP in Arabidopsis thaliana (Koyama et al 2000). Consistent with our results, exogenous application of GAs resulted in increased expression of this enzyme in young seedlings of castor bean (Gonzalez & Delsol 1981;Kagawa & Gonzalez 1981) and Ricinus (Gonzalez & Delsol 1981;Kagawa & Gonzalez 1981).…”

A Formate Dehydrogenase Confers Tolerance to Aluminum and Low pH

“…For example, genes coding for citrate synthase have been introduced into tobacco (Nicotiana tabacum; de la Fuente et al, 1997), Arabidopsis (Koyama et al, 2000), canola (Brassica napus; Anoop et al, 2003), and alfalfa (Medicago sativa; Barone et al, 2008), and genes coding for malate dehydrogenase have been introduced into tobacco and alfalfa (Tesfaye et al, 2001). Similarly, genes related to protection from oxidative stress including manganese superoxide dismutase, dehydroascorbate reductase, peroxidase, and glutathione S-transferase have also been introduced into plants (Ezaki et al, 2000;Basu et al, 2001;Yin et al, 2010).…”