Plant Sterol Diversity in Pollen from Angiosperms
Plant Sterol Diversity in Pollen from Angiosperms
复制标题
DOI：
10.1007/s11745-015-4008-x
复制
发表时间：
2015-08-01
期刊：
影响因子：
1.9
通讯作者：
Schaller, Hubert
中科院分区：
文献类型：
--
作者：
Villette, Claire;Berna, Anne;Schaller, Hubert
在这里，我们已经研究了自由甾醇和甾醇酯的花粉从选定的被子植物物种的组成，作为第一步，对雄配子体甾醇生物合成的全面分析。我们检测到四个主要的甾醇结构组：带有9 β，19-环丙基的环阿屯醇衍生物，在C-7处具有双键的甾醇（8），在C-5处具有双键的甾醇（6）和甾烷醇。所有这些群体在物种之间的分布是不均匀的。然而，花粉粒中甾醇的分布为游离甾醇或甾醇酯，表明游离甾醇主要是δ（5）-甾醇，甾醇酯主要是9 β，19-环丙基甾醇。为了将开花期花粉粒的甾醇成分与花粉管的膜脂成分的要求联系起来，我们从烟草（Nicotiana tabacum）中萌发花粉粒，烟草是生殖生物学中的模式植物。在放射性标记的甲羟戊酸的存在下，并在一个时间过程中的一系列测量，我们表明，cycloeucalenol被确定为主要的新合成的甾醇。此外，抑制cycloeucalenol新合成的角鲨烯抑制素是在一个从头生物发生和一个明显的截断途径在花粉管中完全一致。
Here we have examined the composition of free sterols and steryl esters of pollen from selected angiosperm species, as a first step towards a comprehensive analysis of sterol biogenesis in the male gametophyte. We detected four major sterol structural groups: cycloartenol derivatives bearing a 9 beta,19-cyclopropyl group, sterols with a double bond at C-7(8), sterols with a double bond at C-5(6), and stanols. All these groups were unequally distributed among species. However, the distribution of sterols as free sterols or as steryl esters in pollen grains indicated that free sterols were mostly Delta(5)-sterols and that steryl esters were predominantly 9 beta,19-cyclopropyl sterols. In order to link the sterol composition of a pollen grain at anthesis with the requirement for membrane lipid constituents of the pollen tube, we germinated pollen grains from Nicotiana tabacum, a model plant in reproductive biology. In the presence of radiolabelled mevalonic acid and in a time course series of measurements, we showed that cycloeucalenol was identified as the major neosynthesized sterol. Furthermore, the inhibition of cycloeucalenol neosynthesis by squalestatin was in full agreement with a de novo biogenesis and an apparent truncated pathway in the pollen tube.