title: Persistence and Protection of Mitochondrial DNA in the Generative Cell of Cucumber is Consistent with its Paternal Transmission.
abstract: Plants predominantly show maternal transmission of mitochondrial DNA (mtDNA). One known exception is cucumber, in which the mtDNA is paternally inherited. However, the mechanisms regulating this unique mode of transmission are unclear. Here we monitored the amounts of mtDNA throughout the development of cucumber microspores into pollen and observed that mtDNA decreases in the vegetative cell, but persists in the generative cell that ultimately produces the sperm cells. We characterized the cucumber homolog (CsDPD1) of the Arabidopsis gene defective in pollen organelle DNA degradation 1 (AtDPD1), which plays a direct role in mtDNA degradation. CsDPD1 rescued an Arabidopsis AtDPD1 mutant, indicating the same function in both plants. Expression of CsDPD1 coincided with the decrease of mtDNA in pollen, except in the generative cell where both the expression of CsDPD1 and mtDNA levels remained high. Our cytological results confirmed that the persistence of mtDNA in the cucumber generative cell is consistent with its paternal transmission. Our molecular analyses suggest that protection of mtDNA in the generative cell may be the critical factor for paternal mtDNA transmission, rather than mtDNA degradation mediated by CsDPD1. Taken together, these findings indicate that a mechanism may protect paternal mtDNA from degradation and is likely to be the genetic basis of paternal mtDNA transmission.
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, PR China Department of Horticulture, University of Wisconsin, Madison, WI 53706, USA.
authors.forename: Jia
authors.initials: J
authors.lastname: Shen
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, PR China.
authors.forename: Juan
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Plant Genetics, Breeding and Biotechnology, Faculty of Horticulture, Biotechnology and Lands-ape Architecture, Warsaw University of Life Sciences, ul. Nowoursynowska 159, 02-776 Warsaw, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Bartoszewski
authors.affiliation: Department of Plant Genetics, Breeding and Biotechnology, Faculty of Horticulture, Biotechnology and Lands-ape Architecture, Warsaw University of Life Sciences, ul. Nowoursynowska 159, 02-776 Warsaw, Poland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Malepszy
authors.affiliation: USDA-ARS and Department of Horticulture, University of Wisconsin, Madison, WI 53706, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Havey
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, PR China jfchen@njau.edu.cn.
authors.forename: Jinfeng
authors.initials: J
authors.lastname: Chen
mesh_terms: D003001:Cloning, Molecular; D018553:Cucumis sativus / Q000235:genetics* / Q000254:growth & development; D004272:DNA, Mitochondrial / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics*; D010802:Phylogeny; D011058:Pollen / Q000378:metabolism; D012639:Seeds / Q000378:metabolism
chemical_list: D004272:DNA, Mitochondrial; D018744:DNA, Plant
keywords: CsDPD1; Cucumber; Exonuclease; Paternal transmission; Pollen; mtDNA