目的 筛选罗汉果Siraitia grosvenorii基因表达分析的内参基因，研究苷V生物合成关键酶3-羟基-3-甲基戊二酰辅酶A还原酶（HMGR）时空表达特性。方法 克隆罗汉果看家基因甘油醛-3-磷酸脱氢酶（GAPDH）、微管蛋白（α-tubulin）、肌动蛋白（β-actin）和泛素（UBQ5）的基因片段，评价了4个基因在不同部位（叶、茎和果）及果实发育不同时期的稳定性，筛选内参基因，分析HMGR的时空表达特性。结果 UBQ5表达最稳定，适宜作为内参基因；叶片的HMGR相对表达量较低，茎和果实相对表达量较高；果实不同发育时期，HMGR的相对表达量呈现先升高再降低然后再升高再降低的波动式变化，70 d后HMGR的相对表达量最高，然后依次是5、30、10、50 d。结论 UBQ5是适宜的内参基因。叶片、茎和果实中，HMGR的相对表达量差异明显。果实发育不同时期，HMGR的相对表达量呈波动式变化，与苷V合成积累变化规律相似。

Objective To screen the reference genes of Siraitia grosvenorii for gene expression analysis, and to study the spatio-temporal expression characteristics of 3-hydroxy-3-methylglutaryl coenzyme A (HMGR) which was the key enzyme of mogroside V biosynthesis. Methods In this study, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), microtubule associated protein (α-tubulin), actin (β-actin), and ubiquitin (UBQ5) fragments of S. grosvenorii were cloned, and the stabilities of the four housekeeping genes were evaluated in different positions (leaves, stems, and fruits) and different periods of fruit development. In addition, the spatio-temporal expression of HMGR gene was analyzed. Results UBQ5 was the most suitable reference gene for spatio-temporal expression analysis in S. grosvenorii; The relative expression of HMGR was low in leaves, and that in stems and fruits was higher; The relative expression quantity of HMGR in fruits showed the fluctuation changes that increased firstly and then decreased, then increased and decreased again; The highest expression of HMGR was at 70 d of fruit development period, followed by 5, 30, 10, and 50 d. Conclusion UBQ5 is the most suitable reference gene in S. grosvenorii. The relative expression of HMGR changes significantly in leaves, stems, and fruits. The relative expression quantity of HMGR in fruits shows the fluctuation changes, which is similar to synthetic accumulation pattern of mogroside V.

广西自然科学基金青年基金项目（2011GXNSFB018088）