A Ma10 gene encoding P‐type ATPase is involved in fruit organic acid accumulation in apple

Abstract

Acidity is one of the main determinants of fruit organoleptic quality. Here, comparative transcriptome analysis was conducted between two cultivars that showed a significant difference in fruit acidity, but contained homozygous non-functional alleles at the major gene Ma1 locus controlling apple fruit acidity. A candidate gene for fruit acidity, designated M10, was identified. The M10 gene encodes a P-type proton pump, P -ATPase, which facilitates malate uptake into the vacuole. The Ma10 gene is significantly associated with fruit malate content, accounting for ~7.5% of the observed phenotypic variation in apple germplasm. Subcellular localization assay showed that the Ma10 is targeted to the tonoplast. Overexpression of the Ma10 gene can complement the defect in proton transport of the mutant YAK2 yeast strain and enhance the accumulation of malic acid in apple callus. Moreover, its ectopic expression in tomato induces a decrease in fruit pH. These results suggest that the Ma10 gene has the capacity for proton pumping and plays an important role in fruit vacuolar acidification in apple. Our study provides useful knowledge towards comprehensive understanding of the complex mechanism regulating apple fruit acidity.

BTB-BACK-TAZ domain protein MdBT2-mediated MdMYB73 ubiquitination negatively regulates malate accumulation and vacuolar acidification in apple

“…V-ATPase and V-PPase are both necessary not only for forming and maintaining the electrochemical potential gradient on the tonoplast 2,19 , but also for supplying energy to other transport proteins, such as the malate transporters tDT, Ma1, and Ma10 (refs. 7,12,[20][21][22].…”

Genome-Wide Identification and Characterization of Apple P3A-Type ATPase Genes, with Implications for Alkaline Stress Responses

“…All P 3A -type ATPase genes are considered to be important for transporting H + [63]. A P 3A -type ATPase Ma10 which located to the tonoplast, has the capacity for proton pumping and plays a vital role in vacuolar acidification of apple fruit [29]. Moreover, gene functions are closely associated with the subcellular localization of the encoded protein [2].…”

“…The P 3A -type ATPase genes normally encode proton pumps that are located in the plasma membrane, where they mediate the transport of H + across the plasma membrane and play crucial role in acidification of the aqueous fraction of the cell wall apoplast. In contrast, Ma10 belongs to the P 3A -type ATPase gene family, but the encoded enzyme is localized to the tonoplast, where it promotes the vacuolar acidification of apple fruit [29]. Moreover, PhPH1, which encodes a P-type ATPase belonging to the 3B subfamily in petunia, was believed to comprise only bacterial Mg 2+ transporters [30].…”

BTB-TAZ domain protein MdBT2 modulates malate accumulation by targeting a bHLH transcription factor for degradation in response to nitrate

“…Malate, as a key metabolite, plays a vital role in plant metabolism, pH homeostasis, nutrient uptake, osmotic adjustment and abiotic stress resistance (Fernie and Martinoia, 2009; Finkemeier and Sweetlove, 2009; Bai et al, 2015; Hu et al, 2017). Cellular malate accumulation also largely determines the acidity and perception of sweetness of fleshy fruits and their processed products (Yao et al, 2007; Ye et al, 2017; Butelli et al, 2019; Ma et al, 2019). The majority of malate in the parenchyma cells of fleshy fruits is in the vacuole (Yamaki, 1984).…”

“…Malate accumulation is a complex process involving synthesis, degradation and transport of malate. Although malate metabolism can alter fruit malate level (Sweetman et al, 2009; Centeno et al, 2011), it appears that transport of malate from the cytosol into the vacuole is the step that largely controls malate accumulation (Etienne et al, 2013; Hu et al, 2016a; Ma et al, 2019).…”