Department of Cellular and Molecular Biology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland.
Department of Biochemistry and Cell Biology, Faculty of Biological Sciences, Kazimierz Wielki University, 85-093 Bydgoszcz, Poland.
Int J Mol Sci. 2022 Apr 30;23(9):4987. doi: 10.3390/ijms23094987.
Pollen tube growth depends on several complex processes, including exo/endocytosis, cell wall biogenesis, intracellular transport, and cell signaling. Our previous results provided evidence that calreticulin (CRT)-a prominent calcium (Ca)-buffering molecular chaperone in the endoplasmic reticulum (ER) lumen-is involved in pollen tube formation and function. We previously cloned and characterized the gene belonging to the 2 subgroup from (), and found that post-transcriptional silencing of expression strongly impaired pollen tube growth in vitro. Here, we report cloning of a new homolog; we identified the full-length cDNA sequence and described its molecular characteristics and phylogenetic relationships to other plant genes. Using an RNA interference (RNAi) strategy, we found that knockdown of gene expression caused numerous defects in the morphology and ultrastructure of cultivated pollen tubes, including disorganization of the actin cytoskeleton and loss of cytoplasmic zonation. Elongation of si pollen tubes was disrupted, and some of them ruptured. Our present data provide the first evidence that expression is required for normal pollen tube growth. Thus, we discuss relationships between diverse CRT isoforms in several interdependent processes driving the apical growth of the pollen tube, including actomyosin-dependent cytoplasmic streaming, organelle positioning, vesicle trafficking, and cell wall biogenesis.
花粉管的生长依赖于几个复杂的过程，包括外/内吞作用、细胞壁生物发生、细胞内运输和细胞信号转导。我们之前的结果表明，钙网蛋白（CRT）——内质网（ER）腔中一种重要的钙（Ca）缓冲分子伴侣——参与花粉管的形成和功能。我们之前从 （）中克隆并鉴定了属于 2 亚组的 基因，并发现 的转录后沉默严重损害了体外花粉管的生长。在这里，我们报告了一个新的 同源物的克隆；我们确定了全长 cDNA 序列，并描述了其分子特征及其与其他植物 基因的系统发育关系。利用 RNA 干扰（RNAi）策略，我们发现 基因表达的敲低导致培养花粉管的形态和超微结构出现许多缺陷，包括肌动蛋白细胞骨架的紊乱和细胞质分区的丧失。si 花粉管的伸长被打乱，其中一些管破裂。我们目前的数据首次提供了证据，表明 表达是正常花粉管生长所必需的。因此，我们讨论了不同 CRT 同工型在驱动花粉管顶端生长的几个相互依赖的过程中的关系，包括肌动球蛋白依赖性细胞质流动、细胞器定位、囊泡运输和细胞壁生物发生。
