College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China.
Plant Cell Rep. 2017 Apr;36(4):583-596. doi: 10.1007/s00299-017-2105-4. Epub 2017 Feb 2.
DkXTH1 promoted cell elongation and more strength to maintain structural integrity by involving in cell wall assembly, thus enhanced tolerance to abiotic stress with broader phenotype in transgenic plants. Xyloglucan endotransglucosylase/hydrolase (XTH) is thought to play a key role in cell wall modifications by cleaving and re-joining xyloglucan, and participates in the diverse physiological processes. DkXTH1 was found to peak in immature expanding persimmon fruit, and its higher expression level exhibited along with firmer fruit during storage. In the present study, transgenic Arabidopsis and tomato plants were generated with DkXTH1 constitutively expressed. Overexpression of DkXTH1 enhanced tolerance to salt, ABA and drought stresses in transgenic Arabidopsis plants with respect to root and leaf growth, and survival. Transgenic tomatoes collected at the mature green stage, presented delayed fruit softening coupled with postponed color change, a later and lower ethylene peak, and higher firmness in comparison with the wild-type tomatoes during storage. Furthermore, broader leaves and tomato fruit with larger diameter were gained in transgenic Arabidopsis and tomato, respectively. Most importantly, transgenic plants exhibited more large and irregular cells with higher density of cell wall and intercellular spaces, resulting from the overactivity of XET enzymes involving in cell wall assembly. We suggest that DkXTH1 expression resulted in cells with more strength and thickness to maintain structural integrity, and thus enhanced tolerance to abiotic stress and delayed fruit softening in transgenic plants.
DkXTH1 通过参与细胞壁组装来促进细胞伸长和增强强度以维持结构完整性，从而提高了转基因植物对非生物胁迫的耐受性和更广泛的表型。木葡聚糖内转糖苷酶/水解酶（XTH）被认为通过切割和重新连接木葡聚糖在细胞壁修饰中发挥关键作用，并参与多种生理过程。在未成熟的扩展柿子果实中发现 DkXTH1 达到峰值，其在贮藏过程中随着果实硬度的增加而表达水平升高。在本研究中，通过组成型表达 DkXTH1 生成了转基因拟南芥和番茄植物。与野生型相比，过表达 DkXTH1 增强了转基因拟南芥植物对盐、ABA 和干旱胁迫的耐受性，表现为根和叶生长以及存活率的提高。在成熟绿期收获的转基因番茄表现出延迟的果实软化，伴随着推迟的颜色变化、较低的乙烯峰和较高的硬度，与野生型番茄相比，在贮藏过程中。此外，转基因拟南芥和番茄的叶片变宽，番茄果实直径变大。最重要的是，转基因植物表现出更多的大而不规则的细胞，细胞壁和细胞间隙的密度更高，这是由于参与细胞壁组装的 XET 酶的过度活性所致。我们认为，DkXTH1 的表达导致细胞具有更强的强度和厚度来维持结构完整性，从而提高了转基因植物对非生物胁迫的耐受性和延迟果实软化。
