The fruit of the perennial rosebush Rosa roxburghii were valued for their high levels of ascorbic acid, superoxide dismutase activity, and cancer preventing effects. The high cellulose and low pectin content of Rosa roxburghii fruit results in an undesirable fibrous texture and hence needs to be addressed. However, little is known about the molecular mechanisms underlying dietary fiber metabolism in this fruit. Here, we report that the contents of cellulose, pectin, and lignin were increased by shading treatments at the maturation stage of fruit development. Under 50% shading, the soluble pectin content increased by 16.39%, which may improve the fruit palatability. However, deeper shading of 100% caused the lignin content to increase by 28.86%, which conversely may lower fruit quality. Based on transcriptome analysis, we identified candidate genes involved in dietary fiber metabolism, including cellulose synthase (CesA) 1, 2, 3, and 5, â-1,4-xylosyltransferase (IRX), arabinosyltransferase (ARAD) 1 and 2, galacturonosyltransferase (GAUT), cellulolytic enzyme (Cx), and pectin methylesterase, in which CesA1, CesA2, CesA3, IRX, ARAD2, and GAUT3 significantly responded to shading and positively correlated with the content of their corresponding component. Furthermore, cinnamyl alcohol dehydrogenase was significantly regulated by shading treatment and positively correlated with increasing lignin concentration. These results may facilitate a better understanding of the molecular mechanisms of dietary fiber metabolism in R. roxburghii fruit under low light conditions and provide a framework for future crop improvement.

多年生蔷薇的果实Rosa roxburghii因其高水平的抗坏血酸，超氧化物歧化酶活性和预防癌症而受到重视。罗莎果的高纤维素和低果胶含量水果会产生不良的纤维质感，因此需要解决。然而，人们对这种水果中膳食纤维代谢的分子机制知之甚少。在这里，我们报道在果实发育的成熟阶段，通过遮光处理增加了纤维素，果胶和木质素的含量。在50％的遮荫下，可溶性果胶含量增加了16.39％，这可以改善果实的适口性。但是，更深的100％阴影会使木质素含量增加28.86％，反过来可能会降低果实品质。基于转录组分析，我们确定了涉及膳食纤维代谢的候选基因，包括纤维素合酶（CesA）1、2、3和5，-1,4-木糖基转移酶（IRX），阿拉伯糖基转移酶（ARAD）1和2，半乳糖醛糖基转移酶（GAUT），纤维素分解酶（Cx）和果胶甲基酯酶，其中CesA1，CesA2，CesA3，IRX，ARAD2和GAUT3对阴影具有显着响应，并与它们的对应含量呈正相关成分。此外，肉桂醇脱氢酶受到遮光处理的显着调节，并且与木质素浓度的增加呈正相关。这些结果可能有助于更好地了解罗氏沼虾膳食纤维代谢的分子机制。 在弱光条件下收获果实，并为将来的作物改良提供框架。