Rachis browning is an unfavorable trait of postharvest table grapes (Vitis vinifera L.) and considerably decreases the market value. In this study, we investigated how nitric oxide (NO) delayed the rachis browning progress during cold storage at 0 ± 0.5 °C and during shelf life at 8 ± 0.5 °C and 20 ± 0.5 °C, respectively. The role of NO was explored by changes of storage quality, enzyme activity, and related family gene expression in table grapes cv. Thompson Seedless. The results of transcriptome analysis showed that enzymatic browning might be a main reason for rachis turning brown. NO with 500 μL L⁻¹ treatment was the most effective on inhibiting rachis browning. NO significantly prevented the browning by delaying water loss, reducing phenols accumulation, inhibiting PPO activity, and inducing POD activity. At transcription level, NO significantly down-regulated PPO1, up-regulated POD3, and affected the expression of PAL2 and PAL3 in grape rachis. The expressions of PAL2 and PAL3 showed a positive relation with phenols accumulation. Furthermore, Pearson correlation demonstrated very significant interaction between PPO activity and PPO1 expression, suggesting that PPO1 was the major gene contributing to the observed enzymatic activity. Extremely consistent with the corresponding enzymatic activity and the browning index, suggesting that PPO1 might be crucial to code the enzyme PPO. Based on these findings, NO might be a promising strategy for improving the rachis freshness and extending the shelf life of postharvest table grapes.

Rachis褐变是采后食用葡萄（Vitis vinifera L.）的不利特性，大大降低了市场价值。在这项研究中，我们研究了一氧化氮（NO）如何分别延迟0±0.5°C的冷藏和8±0.5°C和20±0.5°C的货架期褐变过程。通过改变食用葡萄cv的贮藏质量，酶活性和相关家族基因表达来探索NO的作用。汤普森无核。转录组分析结果表明，酶促褐变可能是轮枝变褐的主要原因。NO为500μLL ^-1治疗是最有效的抑制轮轴褐变的方法。NO通过延迟水分流失，减少酚类积累，抑制PPO活性和诱导POD活性来显着防止褐变。在转录水平，NO显着下调PPO1，上调POD3，并影响葡萄叶片中PAL2和PAL3的表达。PAL2和PAL3的表达与酚积累呈正相关。此外，Pearson相关性表明PPO活性与PPO1表达之间存在非常显着的相互作用，这表明PPO1是有助于观察到的酶活性的主要基因。与相应的酶活性和褐变指数极其一致，表明PPO1对编码酶PPO可能至关重要。基于这些发现，NO可能是改善Rachis新鲜度并延长采后食用葡萄货架期的有前途的策略。