Cauliflower (Brassica oleracea L. var. botrytis) inflorescences are composed mainly of meristematic tissue, which has a high cellular proliferation. This considerable cellular density makes the inflorescence an organ with a large proportion of membranes. However, little is known about the specific role of the lipid and protein composition of the plasma membrane present in this organ. In this work, we analyzed the lipids and proteins present in plasma membrane from two different stages of development of cauliflower inflorescence and compared them with leaf plasma membrane. For this purpose, plasma membrane vesicles were obtained by centrifugation for each sample and the vesicular diameter and osmotic permeability (Pf) were analyzed by dynamic light scattering and the stopped-flow technique, respectively. In addition, fatty acids and sterols were analyzed by gas chromatography and HPLC. The protein composition of the inflorescences and leaves was characterized by HPLC-ESI-QTOF-MS and the data obtained were compared with Brassicaceae proteins present in the UniProt database in relation to the presence of aquaporins determined by western blot analysis. The highest Pf value was found in 90 day inflorescences-derived plasma membrane vesicles (61.4 ± 4.14 μms− 1). For sterols and fatty acids, the concentrations varied according to the organ of origin. The protein profile revealed the presence of aquaporins from the PIP1 and PIP2 subfamilies in both inflorescences and leaves. This study shows that the composition of the sterols, the degree of unsaturation of the fatty acids, and the proteins present in the membranes analyzed give them high functionality for water passage. This represents an important addition to the limited information available in this field.

中文翻译：

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花椰菜分生组织的质膜囊泡及其在水通过中的作用

花椰菜（Brassica oleracea L. var. botrytis）花序主要由分生组织组成，具有高度的细胞增殖能力。这种相当大的细胞密度使花序成为具有大量膜的器官。然而，人们对该器官中质膜的脂质和蛋白质成分的具体作用知之甚少。在这项工作中，我们分析了花椰菜花序两个不同发育阶段的质膜中存在的脂质和蛋白质，并将其与叶质膜进行了比较。为此，通过离心获得每个样品的质膜囊泡，并分别通过动态光散射和停流技术分析囊泡直径和渗透率（Pf）。此外，还通过气相色谱法和高效液相色谱法分析了脂肪酸和甾醇。通过 HPLC-ESI-QTOF-MS 表征花序和叶子的蛋白质组成，并将获得的数据与 UniProt 数据库中存在的十字花科蛋白质进行比较，并通过蛋白质印迹分析确定水通道蛋白的存在。最高的 Pf 值出现在 90 天花序衍生的质膜囊泡中 (61.4 ± 4.14 μms−1)。对于甾醇和脂肪酸，其浓度根据来源器官的不同而变化。蛋白质谱显示花序和叶子中都存在 PIP1 和 PIP2 亚家族的水通道蛋白。这项研究表明，甾醇的组成、脂肪酸的不饱和度以及分析膜中存在的蛋白质赋予它们较高的水通过功能。这是对该领域有限信息的重要补充。