Brummell D A, Hall B D, Bennett A B
DNA Plant Technology Corporation, Oakland, CA 94608, USA.
Plant Mol Biol. 1999 Jul;40(4):615-22. doi: 10.1023/a:1006269031452.
Plants of tomato (Lycopersicon esculentum Mill. cv. T5) were transformed with an antisense endo-1,4-beta-glucanase (cellulase, EC 3.2.1.4) Cel2 transgene under the control of the constitutive cauliflower mosaic virus 35S promoter in order to suppress mRNA accumulation of Cel2. In two independent transgenic lines, Cel2 mRNA abundance was reduced by >95% in ripe fruit pericarp and ca. 80% in fruit abscission zones relative to non-transgenic controls. In both transgenic lines the softening of antisense Cel2 fruit pericarp measured using stress-relaxation analysis was indistinguishable from control fruit. No differences in ethylene evolution were observed between fruit of control and antisense Cel2 genotypes. However, in fruit abscission zones the suppression of Cel2 mRNA accumulation caused a significant (P<0.001) increase in the force required to cause breakage of the abscission zone at 4 days post breaker, an increase of 27% in one transgenic line and of 46% in the other transgenic line. Thus the Cel2 gene product contributes to cell wall disassembly occurring in cell separation during fruit abscission, but its role, if any, in softening or textural changes occurring in fruit pericarp during ripening was not revealed by suppression of Cel2 gene expression.
为了抑制内切-1,4-β-葡聚糖酶（纤维素酶，EC 3.2.1.4）Cel2的mRNA积累，用组成型花椰菜花叶病毒35S启动子控制的反义内切-1,4-β-葡聚糖酶（纤维素酶，EC 3.2.1.4）Cel2转基因转化番茄（Lycopersicon esculentum Mill. cv. T5）植株。在两个独立的转基因株系中，与非转基因对照相比，成熟果实果皮中Cel2 mRNA丰度降低了>95%，果实脱落区中降低了约80%。在两个转基因株系中，使用应力松弛分析测定的反义Cel2果实果皮的软化与对照果实没有区别。对照和反义Cel2基因型的果实之间未观察到乙烯释放的差异。然而，在果实脱落区，Cel2 mRNA积累的抑制导致在破色后4天引起脱落区断裂所需的力显著增加（P<0.001），在一个转基因株系中增加了27%，在另一个转基因株系中增加了46%。因此，Cel2基因产物有助于果实脱落过程中细胞分离时发生的细胞壁解体，但通过抑制Cel2基因表达未揭示其在果实成熟期间果皮软化或质地变化中的作用（如果有）。
