Morphology and cell wall composition changes in lignified cells from loquat fruit during postharvest storage
Morphology and cell wall composition changes in lignified cells from loquat fruit during postharvest storage
复制标题
采后贮藏期间枇杷果实木质化细胞形态和细胞壁组成的变化
DOI：
10.1016/j.postharvbio.2019.110975
复制
发表时间：
2019-11-01
影响因子：
7
通讯作者：
Chen, Kunsong
中科院分区：
文献类型：
--
作者：
Huang, Weinan;Zhu, Nan;Chen, Kunsong
枇杷是一种冷敏感性水果，在不适当的低温贮藏条件下，会出现典型的木质化症状，如硬度和木质素含量增加，出汁率下降，风味丧失等。具有木质化症状的枇杷果实中含有木质细胞。本工作对采后枇杷果实木质素染色细胞的发育机制进行了研究。结果表明，木质素染色面积比和木质素细胞密度与果肉硬度和木质素含量均呈显著相关。这些结果表明，枇杷果实采后木质部细胞数量的增加可能是枇杷果实品质劣变的一个重要原因。为了在单细胞水平上理解木质素细胞发育的机制，以无标记的方式可视化了木质素、纤维素和果胶在具有不同形态的木质素细胞的细胞壁中的分布。一般来说，木质化细胞的发育被认为是细胞壁的增厚，直到整个胞腔被填满并且细胞变成完全固体。共聚焦拉曼显微光谱分析结果表明，木质素和纤维素在细胞发育过程中逐渐充满木质细胞，而果胶主要集中在细胞壁角部和中层。木质素和纤维素在木质部细胞中的积累是木质部细胞在发育过程中发生形态变化的主要原因。拉曼光谱提供了丰富的化学键信息，进一步显示了木质素细胞发育过程中木质素官能团的独立分布。此外，在枇杷果肉中，有的木质细胞在发育过程中是单独存在的，周围被薄壁细胞包围;有的木质细胞周围的细胞也积累了木质素，后来变成木质细胞，最终形成几簇木质细胞。通过对枇杷果肉中木质化细胞大小及其簇的分析，认为它们可能不是造成枇杷果肉木质化后口感粗糙的主要原因。本研究结果可作为枇杷果实采后贮藏过程中木质化过程研究的重要补充，主要是在理化和分子水平上进行的。
Loquat, as a cold-sensitive fruit, exhibits typical lignification symptoms, such as increased firmness and lignin content, decreased juice yield and loss of fruit flavor when stored at inappropriately low temperatures. Loquat fruit with lignification symptoms contains lignified cells. This work studied the development mechanism of these cells in postharvest loquat fruit It was found that both the staining area ratios of lignin and the densities of lignified cells had a significant correlation with the firmness and the lignin content of the bulk flesh. These results indicate that the increase of lignified cells might be an important factor in the quality deterioration of postharvest loquat fruit. To understand the mechanism of lignified cell development at the single-cell level, the distribution of lignin, cellulose, and pectin in the cell walls of lignified cells with different morphologies was visualized in a label-free way. In general, the development of the lignified cell was proposed as the thickening of cell walls until the entire intracellular cavity was filled and the cell became total solid. The results of confocal Raman microspectroscopy showed that lignin and cellulose gradually filled the lignified cells during cell development, while pectin was mainly concentrated in the cell wall corner and the middle lamella. The accumulation of lignin and cellulose in the lignified cells was the main cause of the morphological changes in lignified cells during development. The abundant chemical bond information provided by Raman spectra led to further independent distribution imaging of the functional groups of lignin during the development of lignified cells. Besides, in loquat flesh, some lignified cells in the process of development were found alone and surrounded by parenchymal cells; in other cases, some cells around the lignified cells also accumulated lignin and later became lignified cells, eventually forming several clusters of lignified cells. By analyzing the size of lignified cells and their clusters, they might not be the main reason for the rough taste of the loquat flesh with lignification. The results of this work can be an important complement to the study of the lignification process of loquat fruit during postharvest storage that is mainly carried out at the physicochemical and molecular levels.