title: Down-Regulating CsHT1, a Cucumber Pollen-Specific Hexose Transporter, Inhibits Pollen Germination, Tube Growth, and Seed Development.
abstract: Efficient sugar transport is needed to support the high metabolic activity of pollen tubes as they grow through the pistil. Failure of transport results in male sterility. Although sucrose transporters have been shown to play a role in pollen tube development, the role of hexoses and hexose transporters is not as well established. The pollen of some species can grow in vitro on hexose as well as on sucrose, but knockouts of individual hexose transporters have not been shown to impair fertilization, possibly due to transporter redundancy. Here, the functions of CsHT1, a hexose transporter from cucumber (Cucumis sativus), are studied using a combination of heterologous expression in yeast (Saccharomyces cerevisiae), histochemical and immunohistochemical localization, and reverse genetics. The results indicate that CsHT1 is a plasma membrane-localized hexose transporter with high affinity for glucose, exclusively transcribed in pollen development and expressed both at the levels of transcription and translation during pollen grain germination and pollen tube growth. Overexpression of CsHT1 in cucumber pollen results in a higher pollen germination ratio and longer pollen tube growth than wild-type pollen in glucose- or galactose-containing medium. By contrast, antisense suppression of CsHT1 leads to inhibition of pollen germination and pollen tube elongation in the same medium and results in a decrease of seed number per fruit and seed size when antisense transgenic pollen is used to fertilize wild-type or transgenic cucumber plants. The important role of CsHT1 in pollen germination, pollen tube growth, and seed development is discussed.
authors.affiliation: Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China.
authors.forename: Jintao
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China.
authors.forename: Fengzhen
authors.initials: F
authors.lastname: Yao
authors.affiliation: Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Gao
authors.affiliation: Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China.
authors.forename: Si
authors.initials: S
authors.lastname: Ma
authors.affiliation: Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China suixiaolei@cau.edu.cn zhangzx@cau.edu.cn.
authors.forename: Xiaolei
authors.identifier: http://orcid.org/0000-0002-4109-0722
authors.initials: X
authors.lastname: Sui
authors.affiliation: Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China suixiaolei@cau.edu.cn zhangzx@cau.edu.cn.
authors.forename: Zhenxian
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D002241:Carbohydrates; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D018553:Cucumis sativus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D015536:Down-Regulation / Q000187:drug effects; D004734:Energy Metabolism / Q000187:drug effects; D005690:Galactose / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D018525:Germination / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D007700:Kinetics; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009928:Organ Specificity / Q000187:drug effects; D010641:Phenotype; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D053205:Pollen Tube / Q000187:drug effects / Q000254:growth & development* / Q000648:ultrastructure; D016372:RNA, Antisense / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000254:growth & development*; D012689:Sequence Homology, Nucleic Acid
chemical_list: D002241:Carbohydrates; D018076:DNA, Complementary; D009004:Monosaccharide Transport Proteins; D010940:Plant Proteins; D016372:RNA, Antisense; D012333:RNA, Messenger; D005947:Glucose; D005690:Galactose