Vegetative Storage Protein with Trypsin Inhibitor Activity Occurs in Sapindus mukorassi,a Sapindaceae Deciduous Tree

A vegetative storage protein （VSP） with trypsin inhibitor activity in a deciduous tree, Sapindus mukorassi, was characterized by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western-blot, immuno-histochemical localization, light- and electro-microscopy, together with analysis of proteinase inhibitor activity of the purified VSP in vitro. There were two proteins with molecular masses of about 23 and 27 kDa in a relatively high content in the bark tissues of terminal branches of S. mukorassi in leafless periods. The proteins decreased markedly during young shoot development, indicating their role in seasonal nitrogen storage. Immuno-histochemical localization with the polyclonal antibodies raised against the 23 kDa protein demonstrated that the 23 kDa protein was the major component of protein inclusions in protein-storing cells. The protein inclusions were identified by protein-specific staining and should correspond to the electron-dense materials in different forms in the vacuoles of phloem parenchyma cells and phloem ray parenchyma cells under an electron microscope. So, the 23 kDa protein was a typical VSP in S. mukorassi. The 23 and 27 kDa proteins shared no immuno-relatedness, whereas the 23 kDa protein was immuno-related with the 22 kDa VSP in lychee and possessed trypsin inhibitor activity. The 23 kDa protein may confer dual functions： nitrogen storage and defense.

Effect of light quality on total gypenosides accumulation and related key enzyme gene expression in Gynostemma pentaphyllum

Objective： Light quality has effect on the accumulation of gypenosides in the medicinal plant Gynosternma pentaphyllum in the family Cucurbitaceae, while the squalene synthase （SS） and squalene epoxidase （SE） are the key enzymes for gypenoside biosynthesis, The objective of this study was to elucidate the rela- tionship between light quality and biosynthesis key enzyme involving the regulation of gypenoside accu- mulation. Methods： The content of total gypenosides was measured by colorimetric method and the expression of SS and SE gene was determined by quantitative Real-time PCR in the seedlings of G. pentaphyllum which were grown with different light quality. Results： Light quality showed remarkable impacts on the accumulation of total gypenosides. The highest content of total gypenosides in the plant under red light condition was determined, followed by blue light and white light, while the lowest content was recorded under dark condition, qRT-PCR analysis proved that the expression levels of SS and SE genes were also affected by light quality. The high-level gene expressions of SS and SE were found in the plant under red light condition, followed by blue light, with the least content in darkness. The statistical analysis revealed that the total gypenosides were significantly different in different light treatment and the content of total gypenosides was positively related to the expression of SS and SE genes. Conclusions： Light quality regulates gypenoside accumulation via altering the expression of SS and SE in G. pentaphyllum.