Organization Structure Lacquer Paint Production, Development And Study Of The Relationship Between Lacquer

Toxicodendron vernicifluum (Stokes) F. A. Barkley is a kind of special economic tree in China, raw lacquer (also known as oriental lacquer) is the sap obtained by tapping lacquer trees. In this study, the bark structure and seasonal development and its ultrastructural changesof different lacquer trees varieties were characterized with the anatomical technique. Laticiferous canals development in different organs and tylosoids dynamic were also researched in this study. At the basis of those study, comparative studies of bark structure, lacquer yield and urushiel content were carried out with different cultivated T. vernicifluum varieties.The results showed that, the3varieties (Dahongpao, Gaobachi and Ningshan) had roughly similar bark structures, the bark was composed by vascular cambium, secondary phloem and periderm. The vertical system of secondary phloem consists of sieve tubes, companion cells, parenchyma cells, stone cells and secretory ducts, and radial system were composed with the phloem rays. Cambium activity has obvious seasonal variations, vascular cambium dormant in the winter and active in spring and summer. In the newly formed secondary phloem, sieve tube has been developed and mature with transporting function, parenchyma and phloem rays were still in the tender period, the secretion ducts were also in the differentiation period, this part of phloem known as the functional phloem. Outside of the functional phloem secondary phloem is the formation of in previous years, sieve tubes becomes atrophic and loss of transporting function, this part of phloem known as the non-functional phloem and occupied most of the area of bark; in non-functional phloem, the size of parenchyma cells gradually increased and squeezed sieve tubes, Secretory ducts development of mature and secreted a large number of lacquer in the canals, phloem rays can be increased to3-5rows. Moreover, part of the parenchyma cells formed into stone cells cluster in non-functional phloem. Corresponding changes of phloem were also found at ultrastructure level. The mature lumina were surrounded by a layer of secretory cells, which also had two to three layers of surrounding sheath cells. The T. vernicifluum laticiferous canals were mainly distributed in the vascular bundle and produced by the vascular cambium in the functional phloem through schizogenesis. Laticiferous canals distributed in almost all of the organs except the stamens and seeds. Laticiferous canals distributed in pith parenchyma, but it has smaller diameter. Secondary development of laticiferous canals were observed in primary phloem, Schizo-lysigenous of laticiferous canalswere also observed in the stigma of the pistil. Laticiferous canals which distributed in the lacquer tree fructification has special structure, the sheath cells of those laticiferous canals were evolutive but the secretory cells were shrinking.Tylosoids in the lumina oflaticiferous canals originated from epithelia through periclinal division. In the later dovelopment stages, the tylosoid cells disaggregated and the laticiferous canals were blocked by quinone conglomerations. Laticiferous canal invasions varied seasonally, at the beginning of traditional raw lacquer-tapping season, the quinone conglomerations dissolved, laticiferous canal function was renewed and epithelia secreted raw lacquer; at the end of the traditional raw lacquer-tapping season, tylosoids formed and blocked the laticiferous canals by quinone conglomerations until the next raw lacquer-tapping season. The irreversible invasion was mainly distributed in the nonfunctional phloem region near the periderm. These results suggest that the seasonal changes of tylosoids might provide insights into the defense mechanism of laticiferous canals against the invasion of other substances when cavity pressure decreases at the end of the tapping season.The bark structure and major chemical composition of raw lacquer in four cultivated varieties of the lacquer tree, T. vernicifluum, were characterized using the paraffin section technique and high-performance liquid chromatography, respectively. The four varieties had roughly similar bark structures; however, they differed in bark thickness, raw lacquer yields and urushiol homologue content. Laticiferous canal diameter and bark thickness were positively correlated with raw lacquer yields and triene-urushiol content. Our data suggest that bark structure, raw lacquer yield and urushiol homologue content are useful indicators for distinguishing among these four varieties.Raw (oriental) lacquer is the sap obtained by tapping lacquer trees, it has long been used as a coating and painting material because of its excellent waterproofing and antioxidative abilities and corrosion resistance. During past decades, most studies on T. vernicifluum have focused on the morpho-genesis and development of laticiferous canals and the chemical composition of raw lacquer, laid the foundation of lacquer production, processing and lacquer tree varieties bred. This study was carried out on the basis of previous studies, the bark structure and seasonal development and its ultrastructural changes and laticiferous canals development in different organs and tylosoids dynamic were systematicresearched in this study. At the basis of those study, comparative studies of bark structure, lacquer yield and urushiol content were carried out with different cultivated T. vernicifluum varieties. The results can provide a scientific basis to improve the yield and quality of raw lacquer, also can provide new datafor the relationship among the plant structure and development and secondary metabolites production.