Gonçalves Mayara Pereira, Mercadante-Simões Maria Olívia, Ribeiro Leonardo Monteiro
Postgraduate Program in Biotechnology, Department of General Biology, State University of Montes Claros, Montes Claros, MG, 39401-089, Brazil.
Plant Anatomy Laboratory, Department of General Biology, State University of Montes Claros, Montes Claros, MG, 39401-089, Brazil.
Protoplasma. 2018 Nov;255(6):1713-1724. doi: 10.1007/s00709-018-1262-9. Epub 2018 May 18.
Latex is a complex plant secretion with both ecological and economic importance. There is little information currently available on the cytological aspects of the ontogenesis of anastomosed laticifers, the ducts originating through the lysis of adjacent cell walls. Hancornia speciosa is a tree typical of the Cerrado (neotropical savanna) biome. Its latex has medicinal value and is also used to produce rubber. The ontogenesis of its laticifers and the process of latex synthesis are described here. Structural, cytochemical, and ultrastructural analyses of the stem apex and phytochemical analyses of the latex were performed. Laticifer ontogenesis begins early in promeristem cells and subsequently extends through the procambial region. The laticifer precursor cells demonstrate intense metabolic activity, evidenced by starch accumulation and the proliferation of mitochondria, dictyosomes, endoplasmic reticulum, and ribosomes-resulting in the thickening of the cell walls and accumulations of oil droplets in the cytoplasm and fibrous materials in the vacuoles. The ontogenetic process culminates with the partial dissolution of adjacent cell walls and the collapse of the cytoplasm, giving rise to anastomosed laticifers distributed throughout the phloem and adjacent regions of the cortex and medulla. The latex itself is composed of terpenes, mucilage, proteins, alkaloids, and organelle residues that form an emulsion. Laticifer development takes place in three phases: (1) the formation of the emulsion in the promeristem, (2) anastomosis and the collapse of the cytoplasm in the distal region of the procambium, and (3) the maturation of laticifers and latex storage in a central vacuole in the proximal region of the procambium.
乳胶是一种具有生态和经济重要性的复杂植物分泌物。目前关于吻合乳汁管个体发育的细胞学方面的信息很少，乳汁管是通过相邻细胞壁溶解而形成的管道。汉科尼亚木是塞拉多（新热带稀树草原）生物群落中的一种典型树木。其乳胶具有药用价值，也用于生产橡胶。本文描述了其乳汁管的个体发育和乳胶合成过程。对茎尖进行了结构、细胞化学和超微结构分析，并对乳胶进行了植物化学分析。乳汁管的个体发育始于原分生组织细胞早期，随后延伸至原形成层区域。乳汁管前体细胞表现出强烈的代谢活性，淀粉积累以及线粒体、高尔基体、内质网和核糖体的增殖证明了这一点，这导致细胞壁增厚，细胞质中出现油滴积累，液泡中出现纤维物质积累。个体发育过程以相邻细胞壁的部分溶解和细胞质的解体而告终，从而产生分布于整个韧皮部以及皮层和髓质相邻区域的吻合乳汁管。乳胶本身由萜类、黏液、蛋白质、生物碱和细胞器残体组成，形成一种乳液。乳汁管发育分为三个阶段：（1）在原分生组织中形成乳液；（2）在原形成层远端区域吻合和细胞质解体；（3）乳汁管成熟并在原形成层近端区域的中央液泡中储存乳胶。
