Medina Maria Camila, Sousa-Baena Mariane S, Prado Erika, Acevedo-Rodríguez Pedro, Dias Pedro, Demarco Diego
Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.
Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, DC, United States.
Front Plant Sci. 2021 Jan 18;11:612985. doi: 10.3389/fpls.2020.612985. eCollection 2020.
Laticifer occurrence and structure are poorly known in Sapindaceae. Occurrence is likely underestimated owing to the low production of latex in most species. We investigated 67 species from 23 genera of Sapindaceae to verify laticifer occurrence and their structural, developmental and chemical features, as well as their evolutionary history in the family. Shoots were collected from herbarium and fresh specimens for histological analyses. Three characters derived from laticifer features were coded and their ancestral states reconstructed through Bayesian stochastic mapping and maximum likelihood estimation. Only articulated non-anastomosing laticifers were found in Sapindaceae. Laticifers differentiate early during shoot development and are found in the cortex, phloem, and pith. Latex is mostly composed of lipids. Callose and suberin were detected in laticifer cell walls in some genera. Reconstruction of laticifer ancestral states showed that laticifers are present in most clades of Sapindaceae with some reversals. Callose in the laticifer cell wall was found exclusively in and (tribe Paullinieae), a character regarded as independently derived. Occurrence of laticifers in Sapindaceae is broader than previously reported. Articulated non-anastomosing laticifers had five independent origins in Sapindaceae with some secondary losses, occurring in five out of six genera of Paullinieae and 10 other genera outside Paullinieae. Particularly, callose in the laticifer cell wall evolved independently twice in the family, and its occurrence may be interpreted as a key-innovation that promoted the diversification of and . Our study suggests that laticifer characters may be useful in understanding the generic relationships within the family.
无患子科中乳汁管的存在情况和结构鲜为人知。由于大多数物种中乳胶产量较低，其存在情况可能被低估了。我们调查了无患子科23个属的67个物种，以核实乳汁管的存在情况及其结构、发育和化学特征，以及它们在该科中的进化历史。从标本馆和新鲜标本中采集枝条进行组织学分析。对源自乳汁管特征的三个性状进行编码，并通过贝叶斯随机映射和最大似然估计重建其祖先状态。在无患子科中仅发现了有节且不吻合的乳汁管。乳汁管在枝条发育早期分化，存在于皮层、韧皮部和髓中。乳胶主要由脂质组成。在一些属的乳汁管细胞壁中检测到了胼胝质和木栓质。乳汁管祖先状态的重建表明，乳汁管存在于无患子科的大多数分支中，有一些逆转情况。乳汁管细胞壁中的胼胝质仅在[属名1]和[属名2]（泡林藤族）中发现，这一特征被认为是独立衍生的。无患子科中乳汁管的存在比之前报道的更为广泛。有节且不吻合的乳汁管在无患子科中有五个独立的起源，伴有一些次生损失，出现在泡林藤族六个属中的五个以及泡林藤族以外的其他十个属中。特别是，乳汁管细胞壁中的胼胝质在该科中独立进化了两次，其出现可能被解释为促进[属名1]和[属名2]多样化的关键创新。我们的研究表明，乳汁管特征可能有助于理解该科内的属间关系。
