Departamento de Fisiología Vegetal, Facultad de Ciencias, Universidad de Granada, Granada, Spain.
Plant Biol (Stuttg). 2014 Mar;16(2):457-66. doi: 10.1111/plb.12070. Epub 2013 Jul 23.
Studies in zucchini (Cucurbita pepo L. spp. pepo) pollen have been limited to the viability and morphology of the mature pollen grain. The enzyme polygalacturonase (PG) is involved in pollen development and pollination in many species. In this work, we study anther and pollen development of C. pepo and present the cloning and characterisation of a putative PG CpPG1 (Accession no. HQ232488) from pollen cDNA in C. pepo. The predicted protein for CpPG1 has 416 amino acids, with a high homology to other pollen PGs, such as P22 from Oenothera organensis (76%) and PGA3 from Arabidopsis thaliana (73%). CpPG1 belongs to clade C, which comprises PGs expressed in pollen, and presents a 34 amino acid signal peptide for secretion towards the cell wall. DNA-blot analysis revealed that there are at least another two genes that code for PGs in C. pepo. The spatial and temporal accumulation of CpPG1 was studied by semi-quantitative- and qRT-PCR. In addition, mRNA was detected only in anthers, pollen and the rudimentary anthers of bisexual flowers (only present in some zucchini cultivars under certain environmental conditions that trigger anther development in the third whorl of female flowers). However, no expression was detected in cotyledons, stem or fruit. Furthermore, CpPG1 mRNA was accumulated throughout anther development, with the highest expression found in mature pollen. Similarly, exo-PG activity increased from immature anther stages to mature anthers and mature pollen. Overall, these data support the pollen specificity of this gene and suggest an involvement of CpPG1 in pollen development in C. pepo.
关于南瓜(Cucurbita pepo L. spp. pepo)花粉的研究仅局限于成熟花粉粒的活力和形态。多聚半乳糖醛酸酶(PG)在许多物种的花粉发育和授粉过程中都有参与。在这项工作中,我们研究了南瓜的花药和花粉发育,并从南瓜花粉 cDNA 中克隆和鉴定了一个假定的 PG,CpPG1(登录号 HQ232488)。CpPG1 的预测蛋白含有 416 个氨基酸,与其他花粉 PG 如 Oenothera organensis 的 P22(76%)和 Arabidopsis thaliana 的 PGA3(73%)具有高度同源性。CpPG1 属于包含在花粉中表达的 PG 的 C 类,并且具有 34 个氨基酸的信号肽,用于向细胞壁分泌。DNA 印迹分析表明,在南瓜中至少还有另外两个基因编码 PG。通过半定量和 qRT-PCR 研究了 CpPG1 的时空积累。此外,仅在花药、花粉和两性花的原始花药(仅在某些南瓜品种中存在,这些品种在某些环境条件下会触发第三轮雌性花的花药发育)中检测到 mRNA。然而,在子叶、茎或果实中未检测到。此外,CpPG1 mRNA 在整个花药发育过程中积累,在成熟花粉中表达量最高。同样,外切 PG 活性从未成熟的花药阶段增加到成熟的花药和成熟的花粉。总的来说,这些数据支持了该基因在花粉中的特异性,并表明 CpPG1 参与了南瓜花粉的发育。