Physiological regularities of Siraitia grosvenorii mogroside V biosynthesis.

【Objective】To discuss physiological regularities of Siraitia grosvenorii mogroside Ⅴ biosynthesis. 【Method】Comparative experiments of variety,shading,gas storing and low-temperature storing were carried out. Through these experiments,correlations between Siraitia grosvenorii mogrosides and saccharides metabolizing in fruits,effects of photosynthesis,respiration and temperature on them were analysed.【Result and conclusion】In 30 d fruits,mogrosides were mainly mogroside ⅡE and Ⅲ,sucrose and glucose content were low. During 30- 70 d,mogroside ⅡE and Ⅲ content rapidly decreased; sucrose and glucose content increased; mogroside Ⅴ occrred,and its content sharply rose to near the peak value.During 70- 90 d,mogroside Ⅴ was what only detected and found among mogrosides; sucrose content continually increased; glucose content obviously decreased. The higher photosynthetic rates of the variety,the higher its mogroside Ⅴ and glucose content. In shading conditions,photosynthetic rate of leaves decreased,but mogroside Ⅴ and glucose content of fruits both climbed up. Both gas storing and low-tem-perature storing improved glucose accumulation but inhibited mogroside Ⅴ biosynthesis. These studies suggested that low saccharide group mogrosides gradually combined glucoses into mogroside Ⅴ. It did not improve mogroside Ⅴ biosynthesis that leaf photosynthesis and fruit respiration were regulated to increase glucose amount at a late developmental stage. These results showed that low saccharide group mogrosides amount and key enzymatic activities,not the glucose amount,were possibly the main factors of limiting mogroside Ⅴ biosynthesis.