Department of Biotechnology, Motilal Nehru National Institute of Technology Allahabad, Prayagraj, 211004, India.
Department of Botany, Phycology Laboratory, University of Allahabad, Prayagraj, 211002, India.
Planta. 2021 Nov 22;254(6):125. doi: 10.1007/s00425-021-03781-3.
The extrafloral nectaries of S. occidentalis were studied structurally and anatomically (at secretory and post-secretory developmental stages). Role of extrafloral nectaries as a common plant-adoptive characteristic in context to diversity and phylogenetic pattern was also speculated while exploring other collaborative evolutionary implications of this plant. Extrafloral nectaries (EFNs) are widespread and evolutionarily labile traits that have repeatedly and remarkably evolved in vascular plants. Morphological descriptions of the EFNs of certain plant species are common in the literature, but they rarely relate morphology with histology, gland distribution and secretory characteristics. Studies relating EFNs features, i.e., morphology and distribution with their differential visitation by insects, viz. ants and the cost of maintenance to the plants are important to understand the evolution of these glands. Therefore, in this study a morphological, anatomical (structure and ultrastructure) and secretory characterization of EFNs occurring on Senna occidentalis L. is made with the implications of gland attributes discussed from a functional perspective. S. occidentalis L. (Caesalpiniaceae) is an economically important species from industrial, medicinal and agricultural perspective. Observations from the result showed that shape of the EFNs (size 1-2 mm) ranged to globular, ovoid-conical, dome-shaped, fusiform or cylindrical with conical tip. The EFNs were sessile, positioned interpetiolar or seated at the base of petiole. Light and transmission electron microscopic studies showed the specific internal structures of the extrafloral nectary. Two developmental stages of the EFNs (secretory and post-secretory) were recognized. Our current understanding of the phylogenetic patterns of EFNs makes them powerful candidates for future work exploring the drivers of their evolutionary origins, shifts, and losses.
西番莲的额外花蜜腺在结构和解剖学上进行了研究（在分泌和分泌后发育阶段）。在探索这种植物的其他协同进化意义的同时，还推测了额外花蜜腺作为一种常见的植物适应性特征在多样性和系统发育模式中的作用。额外花蜜腺（EFN）是广泛存在且进化不稳定的特征，在维管植物中反复且显著进化。某些植物物种的 EFN 形态描述在文献中很常见，但它们很少将形态与组织学、腺体分布和分泌特征联系起来。将 EFN 特征（形态和分布）与其与昆虫（例如蚂蚁）的差异访问以及对植物的维护成本相关联的研究对于理解这些腺体的进化很重要。因此，在这项研究中，对西番莲中发生的 EFN 进行了形态学、解剖学（结构和超微结构）和分泌特征的描述，并从功能角度讨论了腺体属性的含义。西番莲（豆科）是一种具有经济重要性的物种，从工业、药用和农业角度来看都是如此。结果表明，EFN 的形状（大小为 1-2 毫米）范围为球形、卵球形-圆锥形、圆顶形、梭形或圆柱形，尖端为圆锥形。EFN 是无柄的，位于叶柄间或位于叶柄基部。光镜和透射电子显微镜研究显示了额外花蜜腺的特定内部结构。识别出 EFN 的两个发育阶段（分泌和分泌后）。我们目前对 EFN 系统发育模式的理解使它们成为未来探索其进化起源、转变和丧失驱动因素的工作的有力候选者。
