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Journal of Zhejiang University SCIENCE B
ISSN 1673-1581(Print), 1862-1783(Online), Monthly
2015 Vol.16 No.10 P.845-856
Functional characterization of an invertase inhibitor gene involved in sucrose metabolism in tomato fruit
Abstract: In this study, we produced tomato plants overexpressing an invertase inhibitor gene (Sly-INH) from tomato, using a simple and efficient transient transformation system. Compared with control plants, the expression of Sly-INH was highly upregulated in Sly-INH overexpressing plants, as indicated by real-time polymerase chain reaction (PCR). Physiological analysis revealed that Sly-INH inhibited the activity of cell wall invertase (CWIN), which increased sugar accumulation in tomato fruit. Furthermore, Sly-INH mediated sucrose metabolism by regulating CWIN activity. Our results suggest that invertase activity is potentially regulated by the Sly-INH inhibitor at the post-translational level, and they demonstrate that the transient transformation system is an effective method for determining the functions of genes in tomato.
Key words: Invertase inhibitor, Fruit development, Transient transformation system, Solanum lycopersicum, Overexpression
创新点：首次在番茄果实瞬时表达系统中证明转化酶抑制子可明显抑制细胞壁转化酶活性，并且此抑制作用是通过翻译后水平发挥作用。
方法：将Micro-Tom番茄分为对照组（果实未注射农杆菌及注射不含载体的空白农杆菌）和实验组（果实注射含有过表达转化酶抑制子基因的农杆菌），番茄果实分为萼片、中果肉、胶质胎座和心室隔壁四个部位，用实时定量聚合酶链式反应（qRT-PCR）技术检测转化酶抑制子和转化酶基因家族的表达变化，利用比色法分别检测了蔗糖代谢关键酶活性的变化，用高效液相色谱检测果实各部位果糖、葡萄糖和蔗糖的含量，利用高氯酸水解法测定淀粉的含量。
结论：利用农杆菌注射进行果实瞬时表达后果实各部位的细胞壁转化酶活性受到明显抑制，但转化酶基因家族的转录水平表达变化不大，果糖和葡萄糖含量下降，蔗糖含量有所升高。这一结果表明Sly-INH基因主要是通过在翻译后水平对番茄细胞壁转化酶进行调控，进而影响番茄果实糖的组成与含量。本研究从分子水平对转化酶抑制子及其调控的转化酶基因家族进行了系统性研究，这为利用栽培手段调控植物体内转化酶的表达和活性，调节库组织的蔗糖的输入速率以及同化产物的分配以改善品质提供依据与技术支持。
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DOI:
10.1631/jzus.B1400319
CLC number:
R394-3
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On-line Access:
2015-10-03
Received:
2014-11-19
Revision Accepted:
2015-06-08
Crosschecked:
2015-07-09