Departamento de Biologia Geral, Universidade Estadual de Montes Claros, Montes Claros, 39401-089, Brasil.
Protoplasma. 2023 Mar;260(2):497-508. doi: 10.1007/s00709-022-01792-9. Epub 2022 Jul 8.
An in-depth understanding of the development and distribution of laticifer (latex secretory structure) will be important for the production of both rubber and medicines and will support studies on plant adaptations to their environments. We characterize here and describe the ontogenesis of the laticifer sytem in Calotropis procera (Apocynaceae), an invasive subshrub species in arid landscapes. Anatomical and histochemical evaluations of the primary and secondary structures of the stem were carried out on a monthly basis during a full year, with ultrastructural evaluations of laticifer on the stem apex during the rainy season. In the primary structure, laticifer differentiate early from procambium and ground meristem cells of the cortex and medulla and become concentrated adjacent to the external and internal phloem of the bicollateral bundles. In the secondary structure, laticifer differentiates from fusiform derivative cells of the phloem close to the sieve-tube elements. The laticifer is of the articulated, anastomosing, branched type, and it originates from precursor cells that loose the transversal and longitudinal walls by dissolution. Latex is a mixture of terpenes, alkaloids, flavonoids, mucilage, and proteins. The apical meristem and vascular cambium where the laticifer system begins its development are active throughout the year, including during the dry season. The vascular cambium produces phloem with laticifer precursor cells during the rainy season, with high temperatures and long days. The ability of C. procera to grow under water deficit conditions and produce laticifer throughout the year contribute to its wide distribution in arid environments.
深入了解乳管（乳胶分泌结构）的发育和分布对于橡胶和药物的生产都非常重要，并且有助于研究植物对其环境的适应。我们在这里描述并阐明了入侵性亚灌木物种 Calotropis procera（夹竹桃科）茎中的乳管系统的发生和发育。在一整年中，我们每月对茎的初生和次生结构进行解剖学和组织化学评估，并在雨季对茎尖的乳管进行超微结构评估。在初生结构中，乳管从原形成层和皮层及髓的基本分生组织细胞早期分化，并集中在双韧维管束的外部和内部韧皮部附近。在次生结构中，乳管从靠近筛管分子的韧皮部梭形衍生细胞分化而来。乳管为节状、吻合状、分枝状，起源于通过溶解失去横向和纵向壁的前体细胞。乳胶是萜类、生物碱、类黄酮、黏液和蛋白质的混合物。乳管系统开始发育的顶端分生组织和维管形成层全年都很活跃，包括在旱季。维管形成层在雨季产生具有乳管前体细胞的韧皮部，此时温度高、日照时间长。C. procera 在缺水条件下生长并全年产生乳管的能力有助于其在干旱环境中的广泛分布。
