橡胶树‘热研7-33-97’和‘PR107’胶乳和树皮中蔗糖代谢相关的酶活与基因表达研究

对2个产胶水平差异明显的橡胶树品种（‘热研7-33-97’和‘PR107’）产胶旺季时2个与产胶直接相关的碳库（胶乳和茎干树皮）中蔗糖代谢相关的酶活、基因表达以及胶乳生理参数、树皮非结构性碳水化合物（NSC）含量进行了比较研究。结果表明：‘PR107’干胶产量的季节性变动明显大于‘热研7-33-97’,但均在9月底出现一个产胶高峰;2个品种胶乳的总固形物、无机磷和蔗糖含量差异不明显,但‘热研7-33-97’的干胶含量显著高于‘PR107’;树皮NSC的主要成分为可溶性糖（占80%以上）,但品种间的NSC及其相关组分（淀粉、可溶性糖和还原性糖）的差异均不显著;胶乳中,蔗糖合成酶（Sus）主要催化蔗糖合成,品种间的中碱性转化酶（NIN）和Sus酶活差异均不显著;树皮中,‘热研7-33-97’的NIN酶活显著大于‘PR107’,而其他蔗糖代谢相关酶活品种间的差异不显著;在胶乳中,HbSWEET10a基因的表达量高,并且‘热研7-33-97’>‘PR107’,还是唯一在品种间表达显著差异的蔗糖代谢相关基因;在树皮中,‘PR107’的HbSus3和细胞壁转化酶基因HbCIN2的表达显著高于‘热研7-33-97’,HbSUT5显著低于‘热研7-33-97’,而其他4个蔗糖代谢相关基因的表达在品种间差异不显著。本研究结果为深入探究蔗糖代谢调控与胶乳再生的互作奠定了基础。

Enzymatic Activity and Gene Expression of Sucrose-Metabolizing Enzymes in Latex and Bark of Two Hevea Varieties (‘Reyan7-33-97’ and ‘PR107’)

In this paper, the activity of sucrose-metabolizing enzymes and expression of relevant genes in two carbon sinks (latex and trunk bark) that are directly involved in rubber production, as well as latex physiological parameters and bark n on-structural carbohydrate (NSC), were investigated in two Hevea varieties (‘Reyan7-33-97’ and ‘PR107’) of different rubber productivity during their peak yielding season. Seasonal dynamic change in dry rubber yield was larger in ‘PR107’ than in ‘Reyan7-33-97’, but both varieties exhibited a peak at late Sept. Latex total solid content, inorganic phosphorus and sucrose were not significantly different between the two varieties, but dry rubber content was significantly higher in ‘Reyan7-33-97’ than in ‘PR107’. Soluble sugar accounted for more than 80% of the NSC in trunk bark, and the differences in NSC and its component sugars (starch, soluble sugar and reducing sugar) were not significant between the two varieties. In the latex, sucrose synthase (Sus) catalyzed the reaction towards sucrose synthesis, and the activity of alkaline/neutral invertase (NIN) and Sus was not significantly different between the two varieties. In trunk bark, ‘Reyan7-33-97’ showed significantly higher NIN activity than ‘PR107’, but not significant between the two varieties for the other sucrose-metabolizing enzymes. In the latex, HbSWEET10a was abundantly expressed, and out of the eight sucrose-metabolizing genes examined, it was the only displaying significant differences in expression between the two varieties, with a higher expression in ‘Reyan7-33-97’. In trunk bark, of the seven sucrose-metabolizing genes examined, the expressions of HbSus3 and HbCIN2 were significantly higher in ‘PR107’ than in ‘Reyan7-33-97’, but HbSUT5 expression was lower in ‘PR107’. These results obtained here laid a foundation for further exploring the molecular interaction between the regulation of sucrose metabolism and latex regeneration.