Promoter activity of a putative pollen monosaccharide transporter in Petunia hybrida and characterisation of a transposon insertion mutant

Abstract

Summary.For the growth of the male reproductive cells of plants, the pollen, the presence of sufficient sucrose or monosaccharides is of vital importance. From Petunia hybrida a pollen-specific putative monosaccharide transporter designated PMT1 (for petunia monosaccharide transporter) has been identified previously. The present work provides an in-depth analysis and characterisation of PMT1 in the context of pollen development with the GUS reporter gene and an insertion mutant. The promoter of the pollen-specific putative PMT1 gene has been isolated by inverse PCR and sequenced. Analysis of plants transformed with the promoter-GUS fusion confirmed the specificity of this gene, belonging to the late pollen-specific expressed genes. GUS activity was detected even after 24 h of in vitro pollen germination, at the pollen tube tip. To elucidate the importance of PMT1 for gametophyte development and fertilisation, we isolated a mutant plant containing a transposon insertion in the PMT1 gene by the dTph1 transposon-tagging PCR-based assay. The PMT1 mutant contained a dTph1 insertion in position 1474 bp of the transcribing part of the gene, before the last two transmembrane-spanning domains. Analysis of the progeny of the heterozygous mutant after selfing revealed no alterations in pollen viability and fertility. Mature pollen grains of a plant homozygous for the transposon insertion were able to germinate in vitro in a medium containing sucrose, glucose, or fructose, which indicates that PMT1 is not essential for pollen survival. Several explanations for these results are discussed in the present work.

Disruption of a gene for rice sucrose transporter, OsSUT1, impairs pollen function but pollen maturation is unaffected

“…Moreover, Arabidopsis pollen does germinate on agar media containing glucose but lacking sucrose (Sivitz et al , 2008). However, in their analysis of an insertion mutant of one of the MST genes ( PMT1 ) in Petunia hybrida , Garrido et al (2006) found no defect in pollen function. Further study is clearly needed to characterize the physiological function of MSTs in relation to the function(s) of SUTs in pollen.…”

Down-Regulating CsHT1, a Cucumber Pollen-Specific Hexose Transporter, Inhibits Pollen Germination, Tube Growth, and Seed Development

“…Because germinating pollen grains and growing pollen tubes have no symplastic connection to surrounding tissue, nutrients, including hexoses, must be transferred into the pollen tube by transporters. Although the functional characterization of hexose transporters is fundamental to our understanding of reproductive biology, studies on this subject are mainly limited to Arabidopsis (Schneidereit et al, 2003(Schneidereit et al, , 2005Scholz-Starke et al, 2003) and petunia (Ylstra et al, 1998;Garrido et al, 2006). Furthermore, it is difficult to assign functions to those transporters because single knockouts in these species do not result in phenotypic change.…”

“…Addition of Glc causes instant bursting of Arabidopsis pollen tubes (Schneidereit et al, 2003(Schneidereit et al, , 2005Scholz-Starke et al, 2003). Similarly, there is no phenotype associated with an insertion mutant of Petunia Monosaccharide Transporter1 (PMT1), a putative pollen-specific hexose transporter, of petunia (Ylstra et al, 1998;Garrido et al, 2006).…”

“…After germination of mature pollen grains, the pollen tube must grow rapidly because the distance from the stigma to the embryo sac is often thousands of times the diameter of the pollen grain (Cheung, 1996). The extraordinary speed of pollen tube growth and the extreme length of this single expanding cell require that large amounts of carbohydrate be imported from the pistil for energy consumption and de novo cell wall biosynthesis (Garrido et al, 2006). Any disturbance of either carbohydrate supply or transport capability can significantly impair pollen development or pollen tube growth and cause male sterility (Goetz et al, 2001;Datta et al, 2002;Oliver et al, 2005Oliver et al, , 2007bMamun et al, 2006;Ji et al, 2010).…”

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

“…; Garrido et al . ). In Arabidopsis , many pollen‐specific genes have been identified using different molecular approaches (da Costa‐Nunes & Grossniklaus ).…”