Abstract：
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.
摘要：
深入了解乳胶（乳胶分泌结构）的发展和分布对于橡胶和药物的生产都很重要，并将支持植物适应环境的研究。我们在这里进行了表征并描述了Calotropisprocera（Apocynaceae）中laticifer系统的本体发生，干旱景观中入侵的亚灌木物种。在一整年中每月对茎的一级和二级结构进行解剖和组织化学评估，在雨季期间，对茎尖上的胶乳进行超微结构评估。在一级结构中，laticifer早期与皮质和髓质的原形成层和地面分生组织细胞分化，并集中在双外侧束的外部和内部韧皮部附近。在二级结构中，弹性纤维与靠近筛管元件的韧皮部梭形衍生细胞区分开。laticifer是铰接式的，吻合,分枝型,它起源于通过溶解使横向和纵向壁松散的前体细胞。乳胶是萜烯的混合物,生物碱，黄酮类化合物，粘液，和蛋白质。纤毛系统开始发育的顶端分生组织和维管形成层全年活跃，包括旱季.在雨季，维管形成层产生韧皮部，高温和漫长的日子。C.procera在缺水条件下生长并全年生产胶乳的能力有助于其在干旱环境中的广泛分布。
