刺梨果实膳食纤维组成、积累及其调控的分子生理基础

Fruits of Rosa roxburghii are characteristic and preferentially developmental in Guizhou province because of the high nutrition, health care and medical value.There are many more drugs, health care products, cosmetics and functional foods in exploitation. But now, pomaces became increasingly waste, and preserved fruits tasted roughly which seriously restricted the efficient development of the industry. Therefore, this special fruits would be taken as materials to systematically analyze the dietary fiber composition and accumulation mechanism, attempting to provide fundamental basis for pomace exploitation, and to illuminate the basic reason of texture coarse of processed fruits at the physiological and molecular level. Further more, Rosa roxburghii fruits in early development were treated with light avoidance, Ca2+, ethylene and salicylic acid until fruits ripening, to regulate the dietary fiber composition and accumulation, generating "high fibre" fruits which would be good for pomace exploitation, and "low fibre" fruits which would be benificial to promote quality of processed fruit products.

刺梨因其极高的营养、保健和医药价值而成为贵州省重点发展的特色水果，以其为原料的药品、保健品、化妆品及功能食品的开发方兴未艾。随着加工产业的发展，刺梨果实榨汁后果渣的浪费问题日益严重，同时果脯、蜜饯等加工产品质地粗糙，加工产品品质提升困难或成本太高等问题也严重制约了刺梨产品品质提升和产业的快速发展。因此本项目着眼于刺梨果实膳食纤维的组成及积累机制的研究，以期为刺梨果渣的开发利用提供理论基础，同时从生理及分子水平阐明刺梨果实加工产品质地粗糙的根本原因，并希望进一步通过部分栽培环境因子及部分外源激素处理，调控刺梨果实膳食纤维组成及积累，为定向改良果实品质指明方向：获得的“高纤维”果实将有利于果渣膳食纤维的开发利用，而“低纤维”果实则有利于果脯、蜜饯等加工产品的品质提升。

刺梨果实含有丰富的营养保健价值，也是膳食纤维的良好来源，但其中部分组分也是其加工品质提升的阻碍。通过本研究，我们明确了刺梨果实膳食纤维的组分及其含量等特点，通过转录组数据筛选鉴定出膳食纤维代谢相关基因96个，其中与膳食纤维各主要组分代谢具有相关性的有37个基因。通过RNA-Seq和qRT-PCR系统分析了果实发育过程中及部分栽培环境因子、外源激素处理下各相关基因的表达特点及其与各组分的关系。结果表明：纤维素（CEL）是刺梨果实膳食纤维的主要成分，为膳食纤维总量的47%，占果实干重的约8.74%；半纤维素（HC）为总膳食纤维的27%，总果胶（TP）在总膳食纤维中占18%，木质素（Lignin）含量最少，只占总膳食纤维约8%。总膳食纤维中半乳糖和葡萄糖等单糖含量最多；刺梨木质素单体松柏醇（G-型单体）和芥子醇（S-型单体）比值变化范围为1~3，表明刺梨果实中木质素类型为G-S型。在刺梨果实整个发育时期，纤维素、半纤维素和木质素大致都呈现不断下降的趋势，且CesA1、CesA2、 CesA5，ARAD2、IRX，GAUT3、GAUT4及CCR1、POD1、POD6、HCT等基因分别对纤维素、半纤维素、果胶和木质素的积累起着关键作用。进一步的研究发现，果实遮光、Ca2+以及外源SA、ABA、ETH等生长调节剂均可通过调控相关基因的表达调控刺梨果实膳食纤维相应组分的积累，从而影响果实品质。研究结果为阐明刺梨果实中膳食纤维积累的生理和分子机理提供了科学依据，进而为将来刺梨果实加工品质的定向改良奠定了理论基础并指明了方向。