稳定性同位素表征杨梅果实采后损伤胁迫呼吸代谢机理研究

Chinese bayberry (Myrica rubra Sieb. et Zucc.) is one of unique fruits in China and loved by the public. It is vulnerable to be suffered from mechanical wounding because of its thin exocarp. The past researches on Chinese bayberry of physiological and metabolic mechanisms under wounding stress were mainly from the active material decay, enzyme activity changes and signal transduction. The response mechanism of mechanical wounding stress was partly expounded. The stable isotope ratios is one of characterization methods based on differences between atoms, is the inherent feature of all things contained. The characteristic fingerprint of physiological metabolic processes wound been provided accurately and reliably by the stable isotope. The Chinese bayberry under wounding stress as the object, the stable isotope ratios as a characterization method were used to explore the isotope fractionation rules of respiratory metabolism. The changes of physiological and biochemical of Chinese bayberry under different wounding stress wound be clarified. The differences of respiratory metabolic pathways and metabolic substrates wound be resolved. It wound be hoped to reveal the impact mechanism of bayberry postharvest wounding stress on the respiratory metabolism, provide a new theory and pathway to develop the storage and preservation techniques for Chinese bayberry.

杨梅是近年发展迅速的特色潜力水果，深受人们喜爱。因其外果皮薄，采后极易发生机械损伤，造成严重腐烂和损失。以往研究多关注杨梅采后的生理变化，大多集中采后衰老、酶活性、品质和信号传导等，部分研究明确了其在损伤胁迫下的某些生理生化应答。基于同位素水平探究杨梅采后损伤胁迫下的呼吸代谢机制变化尚未见报道。稳定性同位素比率是基于原子间水平的表征手段，是物质自身携带的固有特征，能更深刻真实有效地表征反映鲜活果实采后代谢途径相关的特征指纹信息，更准确可靠地解析呼吸代谢途径和底物等的变化机理。本项目以采后损伤胁迫的杨梅果实为对象；拟创新采用稳定性同位素表征方法，研究呼吸代谢途径对同位素分馏的作用与影响规律；精确阐明杨梅果实采后在不同损伤胁迫下发生的呼吸代谢底物的变化；旨从原子间水平，揭示损伤胁迫对杨梅果实采后呼吸代谢的影响机理，为杨梅果实采后保鲜调控提供理论依据，亦将为果蔬采后贮藏研究探索开辟科学新方法。

杨梅风味独特，深受消费者喜爱。但杨梅果实皮薄多汁，极易在采后物流过程中遭受损伤胁迫，其生理代谢速率和方式发生改变，使体内的营养物质发生代谢途径和效率，进而引起稳定性同位素分馏效应，同位素比率发生变化。项目基于稳定性同位素技术表征了损伤胁迫呼吸代谢途径和底物的变化机制。（1）杨梅损伤胁迫下的品质差异性分析和稳定性同位素分馏规律，震荡处理组在贮藏后期可以显著的提高了杨梅的腐烂率，呼吸强度显著加大。在不同贮藏时间下稳定性同位素比率，由于有机物消耗加剧，出现了分馏积聚效应。（2）杨梅损伤造成的“伤呼吸”胁迫下的呼吸代谢途径变化，通过建立与实际冷藏运输相近的三轴向模拟运输振动，比较振动杨梅果实与静置杨梅果实不同途径呼吸速率及品质因子的差异和关联，分析了糖酵解途径、三羧酸循环途径、戊糖磷酸途径在震动胁迫下的改变，关联稳定性同位素，进行LDA降维分析，100%被分离到椭圆置信区。（3）杨梅营养物质分离纯化及同位素的分馏规律，杨梅果实中存在着大量有机物质，在受到损伤胁迫后，其分解代谢会出现差异化利用，研究采用制备式的高效液相色谱仪进行，分离纯化得到不同组分。基于分离纯化的呼吸代谢底物，分析了呼吸代谢底物的同位素分馏动态特性。