Purification, Biochemical and Immunological Characterization of Acid Invertases from Apple Fruit

: The soluble acid invertase (SAI) and cell wall-bound invertase (CWI) were purified from apple fruit to apparent electrophoretic homogeneity. Based on sequencing, substrate specificity, and immunoblotting assay, the purified enzymes were identified to be two isoforms of acid invertase (β-fructosidase; EC 3.2.1. 26). The SAI and CWI have the same apparent molecular mass with a holoenzyme of molecular mass of 220 kDa composed of 50 kDa subunits. The SAI has a lower Km value for sucrose and higher Km for raffinose compared with CWI. These acid invertases differ from those in other plants in some of their biochemical properties, such as the extremely high Km value for raffinose, no hydrolytic activity for stachyose, and a mixed form of inhibition by fructose to their activity. The antibodies directed against the SAI and CWI recognized, from the crude extract, three polypeptides with a molecular mass of 50, 68, and 30 kDa, respectively. These results provide a substantial basis for the further studies of the acid invertases in apple fruit.

木薯细胞壁酸性转化酶MeCWINCV5基因启动子的克隆和序列分析

[目的]了解MeCWINCV5在植物生长发育、激素调节和逆境胁迫应答中的功能。[方法]采用PCR方法从木薯基因组中分离MeCWINCV5基因启动子序列,考察MeCWINCV5对植物生长发育、激素调节和逆境胁迫应答的影响。[结果]分析显示启动子的长度为1 170 bp,含有TATA box和CAAT box等多个典型的真核生物启动子基本元件元件,还存在大量逆境胁迫诱导相关的顺式调控元件,如HSE、MBS、SARE、GARE-motif和TATC-box等多个与植物逆境胁迫相关的元件。[结论]MeCWINCV5基因启动子与逆境胁迫有关,在木薯抵御逆境胁迫的生理过程中具有重要作用。

木薯细胞壁酸性转化酶基因MeCWINV1启动子的克隆及其在烟草中的瞬时表达分析

为了解木薯细胞壁酸性转化酶基因Me CWINV1胁迫诱导模式及调控机制,本研究利用PCR的方法,从木薯基因组中分离到一段Me CWINV1基因启动子序列(Gen Bank登录号:KC465190)。分析结果显示,该启动子长度865 bp,含有TATA box和CAAT box保守元件,以及MBS、HSE、AT1等多个与植物逆境胁迫相关的元件。通过构建GUS基因融合表达载体,对该启动子在烟草中的瞬时表达进行分析。结果表明,GUS基因主要在烟草叶脉中表达。研究结果为进一步研究该启动子的功能奠定了基础。