Ethylene treatment promotes umami taste-active amino acids accumulation of Torreya grandis nuts post-harvest by comparative chemical and transcript analyses

Amino acids play critical roles in physiological processes and also contribute significantly to fruit quality. In this study, the effect of exogenous ethylene on amino acids metabolism and related genes expression in Torreya grandis were investigated. The results revealed that ethylene treatment (3000 mu L L-1 for 24 h) significantly increased amino acids level. Umami amino acids were distinctly upregulated in ethylene-treated versus control nuts, with glutamic and aspartic acids to demonstrate 1.9-fold and 2.1-fold increase. Transcriptome analysis revealed that deferentially expressed genes were mainly enriched in alanine aspartate and glutamate meta-bolism. RT-qPCR confirmed that ethylene treatment up-regulated expression of their biosynthesis genes (TgGOGAT1, TgAATC1, TgAATC4) concurrent with suppression of their degradation enzymes (TgGS2, TgGAD1, TgGAD3, TgASNS1). Ethylene treatment appears to promote umami taste-active amino acids and improve T. grandis nut quality post-harvest.

Automated summary

Exogenous ethylene treatment significantly increased the levels of amino acids, especially umami amino acids, in Torreya grandis nuts. Glutamic and aspartic acids showed a 1.9-fold and 2.1-fold increase, respectively. Transcriptome analysis revealed differential expression of genes involved in alanine, aspartate, and glutamate metabolism. RT-qPCR confirmed upregulation of biosynthesis genes (TgGOGAT1, TgAATC1, TgAATC4) and suppression of degradation enzymes (TgGS2, TgGAD1, TgGAD3, TgASNS1) after ethylene treatment. Ethylene treatment appears to enhance umami taste-active amino acids and improve the quality of T. grandis nuts.