Tomato Oxalyl-CoA Synthetase Degrades Oxalate and Affects Fruit Quality

• Published in: Frontiers in plant science Vol. 13; p. 951386
• Main Authors: Li, Pengfei, He, Qiyu, Jin, Jianfeng, Liu, Yu, Wen, Yuxin, Zhao, Kai, Mao, Guangqun, Fan, Wei, Yang, Jianli
• Format: Journal Article
• Language: English
• Published: Frontiers Media S.A 07.07.2022
• Subjects: AAE3 gene; fruit development; fruit quality; oxalate; Plant Science; redox metabolism
• ISSN: 1664-462X; 1664-462X
• DOI: 10.3389/fpls.2022.951386

Acyl activating enzyme 3 (AAE3) encodes oxalyl-CoA synthetase involved in oxalate degradation. In this study, we investigated the role of AAE3 (SlAAE3) in the fruit quality of tomato ( Solanum lycopersicum ). The purified recombinant SlAAE3 protein from Escherichia coli exhibited a high activity toward oxalate, with a K m of 223.8 ± 20.03 μm and V max of 7.908 ± 0.606 μmol mg –1 protein min –1 . Transient expression of SlAAE3-green fluorescent protein (GFP) fusion proteins suggests that SlAAE3 is a soluble protein without specific subcellular localization. The expression of SlAAE3 is both tissue- and development-dependent, and increased during fruit ripping. The Slaae3 knockout mutants had improved fruit quality as evidenced by the increased sugar-acid ratio and mineral nutrient content. To find the mechanism by which SlAAE3 affects fruit quality, transcriptome, and metabolome were employed on SlAAE3 over-expressed line and wide type fruits. The transcriptomic and metabolic profiles indicated that SlAAE3 in fruits mainly functions at 20 days post-anthesis (20 DPA) and mature green (MG) stages, resulting in up-regulation of amino acid derivatives, nucleotides, and derivatives, but down-regulation of lipid compounds. However, differentially expressed genes (DEGs) were mainly enriched at redox pathways. Taken together, both in vivo and in vitro results suggest that SlAAE3-encoded protein acts as an oxalyl-CoA synthetase, which also participates in redox metabolism. These data provide a further understanding of the mechanism by which SlAAE3 participates in tomato fruit quality.