Kalamaki Mary S, Harpster Mark H, Palys Joseph M, Labavitch John M, Reid David S, Brummell David A
Department of Food Science and Technology, University of California, Davis, California 95616.
J Agric Food Chem. 2003 Dec 3;51(25):7456-64. doi: 10.1021/jf034164l.
Processing tomato lines suppressed in the accumulation of ripening-related polygalacturonase or expansin were generated by introduction of transgenes to silence expression of the LePG and LeExp1 genes, respectively. The rheological properties of juice and juice reconstituted from paste produced from lines suppressed in one of these genes, or in both, were compared with azygous controls. When assayed by measuring Bostwick consistency, paste produced from either suppressed LePG or suppressed LeExp1 lines and diluted to 5 degrees Brix was approximately 18% more viscous than that produced from controls. Simultaneous suppression of LePG and LeExp1 produced a small additional increase in viscosity of 4%. Rheometric flow analysis at 5 or 10 degrees Brix also showed substantial increases in the consistency index due to suppression of either LePG or LeExp1 alone, and a small additional increase when both genes were suppressed in the same transgenic line. Measurements by laser diffraction and [1H]NMR showed that suppression of LePG or LeExp1 accumulation altered the size distribution of insoluble particles and modified their surface properties. The data are consistent with suppression of LePG increasing serum viscosity, and suppression of either LePG or LeExp1 altering the properties of the insoluble particles and improving some aspect of particle-particle or particle-serum interaction, or both. However, relative to that caused by suppression of either gene alone, the additional increase in viscosity caused by simultaneous suppression of LePG and LeExp1 together was slight.
通过导入转基因分别沉默LePG和LeExp1基因的表达，培育出了在成熟相关多聚半乳糖醛酸酶或膨胀素积累方面受到抑制的加工番茄品系。将这些在其中一个基因或两个基因中受到抑制的品系所制得的果汁以及由其制成的酱再重构得到的果汁的流变学特性，与非转基因对照进行了比较。通过测量博斯特威克稠度进行测定时，由LePG受到抑制或LeExp1受到抑制的品系所制得并稀释至5°白利糖度的酱，其粘性比对照所制得的酱大约高18%。同时抑制LePG和LeExp1会使粘度小幅额外增加4%。在5°或10°白利糖度下的流变流动分析也表明，由于单独抑制LePG或LeExp1，稠度指数大幅增加，而在同一转基因品系中两个基因都受到抑制时，会有小幅额外增加。通过激光衍射和[1H]核磁共振测量表明，抑制LePG或LeExp1的积累会改变不溶性颗粒的尺寸分布并改变其表面性质。这些数据与抑制LePG增加血清粘度、抑制LePG或LeExp1改变不溶性颗粒的性质并改善颗粒间或颗粒与血清相互作用的某些方面（或两者）是一致的。然而，相对于单独抑制任一基因所导致的情况，同时抑制LePG和LeExp1一起所导致的粘度额外增加是轻微的。
