A novel allele of L-galactono-1,4-lactone dehydrogenase is associated with enhanced drought tolerance through affecting stomatal aperture in common wheat

Abstract

In higher plants, L-galactono-1,4-lactone dehydrogenase (GLDH) plays important roles in ascorbic acid (AsA) biosynthesis and assembly of respiration complex I. Here we report three homoeologous genes (TaGLDH-A1, -B1 and -D1) encoding common wheat GLDH isozymes and a unique allelic variant (TaGLDH-A1b) associated with enhanced drought tolerance. TaGLDH-A1, -B1 and -D1 were located on chromosomes 5A, 5B and 5D, respectively, and their transcripts were found in multiple organs. The three homoeologs each conferred increased GLDH activity when ectopically expressed in tobacco. Decreasing TaGLDH expression in wheat significantly reduced GLDH activity and AsA content. TaGLDH-A1b differed from wild type allele TaGLDH-A1a by an in-frame deletion of three nucleotides. TaGLDH-A1b was biochemically less active than TaGLDH-A1a, and the total GLDH activity levels were generally lower in the cultivars carrying TaGLDH-A1b relative to those with TaGLDH-A1a. Interestingly, TaGLDH-A1b cultivars showed stronger water deficiency tolerance than TaGLDH-A1a cultivars, and TaGLDH-A1b co-segregated with decreased leaf water loss in a F2 population. Finally, TaGLDH-A1b cultivars generally exhibited smaller leaf stomatal aperture than TaGLDH-A1a varieties in control or water deficiency environments. Our work provides new information on GLDH genes and function in higher plants. TaGLDH-A1b is likely useful for further studying and improving wheat tolerance to drought stress.

Elevating Ascorbate in Arabidopsis Stimulates the Production of Abscisic Acid, Phaseic Acid, and to a Lesser Extent Auxin (IAA) and Jasmonates, Resulting in Increased Expression of DHAR1 and Multiple Transcription Factors Associated with Abiotic Stress Tolerance

“…The response of DHAR1 expression could instead be due to downstream effects of elevated AsA which induced a change in phytohormones, which in turn likely activated the expression of transcription factor genes associated with abiotic stresses. There are numerous reports linking increased AsA (as well as AsA recycling) with increased tolerance to abiotic stresses, drought and salinity in particular [33,54,[87][88][89][90][91][92][93][94][95][96][97]. Abiotic stress leads to a range of alterations in metabolism, altered phytohormone balances, ROS imbalances, and formation of stress metabolites are perceived and integrated by triggering signal transduction pathways which further impact hormone and ROS levels.…”

Ascorbate and Thiamin: Metabolic Modulators in Plant Acclimation Responses

“…In addition to its role in central metabolism, studies in different plant species have shown that alterations in the levels of thiamin vitamers result in smaller plants, chlorosis of the leaves, growth retardation, delayed flowering, fitness cost, and an influence on yield penalty [25,26,105,111,133,134]. Some of these phenotypes, such as chlorosis and the delayed flowering, have also been shown to be dependent on the light regime [25,32].…”

Effects of endogenous ascorbic acid on resistance to high-temperature stress in excised rice leaves

“…---It has been reported that l-galactono-1,4-lactone dehydrogenase (GLDH) was the rate-limiting enzyme in Asc synthesis (Smirnoff et al 2001), and the Asc content in plants was positively correlated with the expression of GLDH gene (Landi et al 2015, Zhang et al 2016, Tokunaga et al 2005. GLDH up-regulated and the GLDH down-regulated rice strains had been successfully constructed (Yu et al 2010(Yu et al , 2017.…”