During pollen maturation, various organelles change their distribution and function during development as male gametophytes. We analyzed the behavior of lipid bodies and vacuoles involved in lipophagy in Arabidopsis pollen using serial section SEM and conventional TEM. At the bicellular pollen stage, lipid bodies in the vegetative cells lined up at the surface of the generative cell. Vacuoles then tightly attached, drew in, and degraded the lipid bodies and eventually occupied the space of the lipid bodies. Degradation of lipid began before transfer of the entire contents of the lipid body. At the tricellular stage, vacuoles instead of lipid bodies surrounded the sperm cells. The degradation of lipid bodies is morphologically considered microautophagy. The atg2-1 Arabidopsis mutant is deficient in one autophagy-related gene ( ATG ). In this mutant, the assembly of vacuoles around sperm cells was sparser than that in wild-type pollen. The deficiency of ATG2 likely prevents or slows lipid degradation, although it does not prevent contact between organelles. These results demonstrate the involvement of microlipophagy in the pollen development of Arabidopsis .

中文翻译：

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拟南芥花粉中生殖细胞和精子细胞周围液泡和脂质体相互作用诱导的微脂体超微结构表征

在花粉成熟过程中，各种细胞器在作为雄配子体的发育过程中会改变它们的分布和功能。我们使用连续切片 SEM 和常规 TEM 分析了拟南芥花粉中脂质体和液泡的行为。在双细胞花粉阶段，营养细胞中的脂质体排列在生殖细胞的表面。液泡紧贴、吸入、降解脂质体，最终占据脂质体的空间。脂质的降解在脂质体的全部内容物转移之前就开始了。在三细胞阶段，精子细胞周围是液泡而不是脂质体。脂质体的降解在形态上被认为是微自噬。atg2-1 拟南芥突变体缺乏一种自噬相关基因 (ATG)。在这个突变体中，精子细胞周围的液泡组装比野生型花粉少。ATG2 的缺乏可能会阻止或减缓脂质降解，尽管它不会阻止细胞器之间的接触。这些结果证明了拟南芥花粉发育中微脂蛋白的参与。