Abstract：
Plant rhamnogalacturonan lyases (RGLyases) cleave the backbone of rhamnogalacturonan I (RGI), the \"hairy\" pectin and polymer of the disaccharide rhamnose (Rha)-galacturonic acid (GalA) with arabinan, galactan or arabinogalactan side chains. It has been suggested that RGLyases could participate in remodeling cell walls during fruit softening, but clear evidence has not been reported. To investigate the role of RGLyases in strawberry softening, a genome-wide analysis of RGLyase genes in the genus Fragaria was performed. Seventeen genes encoding RGLyases with functional domains were identified in Fragaria × ananassa. FaRGLyase1 was the most expressed in the ripe receptacle of cv. Chandler. Transgenic strawberry plants expressing an RNAi sequence of FaRGLyase1 were obtained. Three transgenic lines yielded ripe fruits firmer than controls without other fruit quality parameters being significantly affected. The highest increase in firmness achieved was close to 32%. Cell walls were isolated from ripe fruits of two selected lines. The amount of water-soluble and chelated pectins was higher in transgenic lines than in the control. A carbohydrate microarray study showed a higher abundance of RGI epitopes in pectin fractions and in the cellulose-enriched fraction obtained from transgenic lines. Sixty-seven genes were differentially expressed in transgenic ripe fruits when compared with controls. These genes were involved in various physiological processes, including cell wall remodeling, ion homeostasis, lipid metabolism, protein degradation, stress response, and defense. The transcriptomic changes observed in FaRGLyase1 plants suggest that senescence was delayed in transgenic fruits.
摘要：
植物鼠李糖半乳糖醛酸裂解酶（RGLyases）切割鼠李糖半乳糖醛酸I（RGI）的骨架，双糖鼠李糖（Rha）-半乳糖醛酸（GalA）与阿拉伯聚糖的“毛状”果胶和聚合物，半乳聚糖或阿拉伯半乳聚糖侧链。有人认为，RGLyase可以参与果实软化过程中的细胞壁重塑，但是没有明确的证据。探讨RGLyase在草莓软化中的作用,对Fragaria属的RGLyase基因进行了全基因组分析。在Fragaria×ananassa中鉴定了17种编码具有功能域的RGLyase的基因。FaRGLyase1在cv的成熟容器中表达最多。钱德勒.获得表达FaRGLyase1的RNAi序列的转基因草莓植物。三个转基因品系的成熟果实比对照结实，而其他果实品质参数没有受到显着影响。获得的最高硬度增加接近32%。从两个选定品系的成熟果实中分离细胞壁。转基因品系中水溶性和螯合果胶的含量高于对照。碳水化合物微阵列研究表明，在果胶级分和从转基因系获得的富含纤维素的级分中，RGI表位的丰度更高。与对照相比，转基因成熟果实中有67个基因差异表达。这些基因参与各种生理过程，包括细胞壁重塑，离子稳态，脂质代谢，蛋白质降解，应激反应，和防御。在FaRGLyase1植物中观察到的转录组变化表明，转基因果实的衰老被延迟。
