Cloning and characterisation of a putative pollen‐specific polygalacturonase gene (CpPG1) differentially regulated during pollen development in zucchini (Cucurbita pepo L.)

Abstract

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.

Cell wall metabolism and chilling injury during postharvest cold storage in zucchini fruit

“…The homogenate was centrifuged at 4 C and 4000 Â g for 20 min and the supernatant was used as enzymatic extract. The PG and CEL activities assay was based on the release of reducing groups produced using the method described by Wang et al (1997) with modifications according to Carvajal et al (2014). The reaction mixture contained 0.2 mL enzymatic extract and 0.8 mL polygalacturonic acid or carboxymethyl cellulose 0.5% (w/v) in 0.1 M sodium acetate buffer pH 5 for PG and CEL, respectively.…”

BcMF26a and BcMF26b Are Duplicated Polygalacturonase Genes with Divergent Expression Patterns and Functions in Pollen Development and Pollen Tube Formation in Brassica campestris

“…Moreover, BcMF6 , BcMF16 , and BcMF17 in B . campestris and CpPG1 in zucchini ( Cucurbita pepo L.) are important for pollen development [ 15 – 18 ].…”

Identification of a gene encoding polygalacturonase expressed specifically in short styles in distylous common buckwheat (Fagopyrum esculentum)

“…In the phylogenetic tree, FePG1 was placed in clade C (Supplementary Fig. S1), which includes exo-PGs that may be involved in pollen development and floral morphology, e.g ., style length and anther height (Athanasiou et al 2003; Zhang et al 2008; Huang et al 2009a, b; Carvajal et al 2014; Yu et al 2014). Therefore, FePG1 may have a role in the development of floral morphology or be related to self-incompatibility through pollen tube development.…”