Cytosolic/Plastid Glyceraldehyde-3-Phosphate Dehydrogenase Is a Negative Regulator of Strawberry Fruit Ripening

Abstract

Cytosolic glyceraldehyde-3-phosphate dehydrogenase (GAPC) and plastid glyceraldehyde-3-phosphate dehydrogenase (GAPCp) are key enzymes in glycolysis. Besides their catalytic function, GAPC/GAPCp participates in the regulation of plant stress response and growth and development. However, the involvement of GAPC/GAPCp in the regulation of fruit ripening is unclear. In this study, <i>FaGAPC2</i> and <i>FaGAPCp</i>1 in strawberries were isolated and analyzed. <i>FaGAPC2</i> and <i>FaGAPCp</i>1 transcripts showed high transcript levels in the fruit. Transient overexpression of <i>FaGAPC2</i> and <i>FaGAPCp</i>1 delayed fruit ripening, whereas RNA interference promoted fruit ripening and affected fruit anthocyanins and sucrose levels. Change in the expression patterns of <i>FaGAPC2</i> and <i>FaGAPCp</i>1 also influenced the expression of several glycolysis-related and ripening-related genes such as <i>CEL1</i>, <i>CEL2</i>, <i>SS</i>, <i>ANS</i>, <i>MYB5</i>, <i>NCED1</i>, <i>ABI1</i>, <i>ALDO</i>, <i>PK</i>, and <i>G6PDH</i>, and H₂O₂ level and reduced glutathione (GSH)/glutathione disulfide (GSSG) redox potential. Meanwhile, metabolomics experiments showed that transient overexpression of <i>FaGAPCp</i>1 resulted in a decrease in anthocyanins, flavonoids, organic acid, amino acids, and their derivatives. In addition, abscisic acid (ABA) and sucrose treatment induced the production of large amounts of H₂O₂ and inhibited the expression of <i>FaGAPC2</i>/<i>FaGAPCp</i>1 in strawberry fruit. These results revealed that <i>FaGAPC2</i>/<i>FaGAPCp</i>1 is a negative regulator of ABA and sucrose mediated fruit ripening which can be regulated by oxidative stress.