title: MutS HOMOLOG1 silencing mediates ORF220 substoichiometric shifting and causes male sterility in Brassica juncea.
abstract: Cytoplasmic male sterility (CMS) has consistently been associated with the expression of mitochondrial open reading frames (ORFs) that arise from genomic rearrangements. Spontaneous fertility reversion in CMS has been observed in several cases, but a clear understanding of fertility reversion controlled by nuclear genetic influences has been lacking. Here, we identified spontaneous fertile revertant lines for Brassica juncea CMS cytoplasm in which the mitochondrial genome has undergone substoichiometric shifting (SSS) to suppress ORF220 copy number. We placed ORF220, with or without a mitochondrial targeting presequence, under the control of the CaMV35S and AP3 promoters in Arabidopsis to confirm that ORF220 causes male sterility when mitochondrially localized. We found that copy number of the ORF220 gene was altered under conditions that suppress MSH1, a nuclear gene that controls illegitimate recombination in plant mitochondria. MSH1-RNAi lines with increased ORF220 copy number were male sterile compared with wild type. We found that a wide range of genes involved in anther development were up- and down-regulated in revertant and MSH1-RNAi lines, respectively. The system that we have developed offers valuable future insight into the interplay of MSH1 and SSS in CMS induction and fertility reversion as a mediator of nuclear-mitochondrial crosstalk.
authors.affiliation: Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou 310058, China.
authors.forename: Na
authors.initials: N
authors.lastname: Zhao
authors.affiliation: Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou 310058, China.
authors.forename: Xinyue
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE 68588-0660, USA.
authors.forename: Yashitola
authors.initials: Y
authors.lastname: Wamboldt
authors.affiliation: Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE 68588-0660, USA.
authors.forename: Sally A
authors.initials: SA
authors.lastname: Mackenzie
authors.affiliation: Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE 68588-0660, USA. yangjinghua@zju.edu.cn.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Yang
authors.affiliation: Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou 310058, China. Key laboratory of Horticultural Plant Growth, Development & Quality Improvement, Ministry of Agriculture, Hangzhou 310058, China. Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Hangzhou 310058, China.
authors.forename: Zhongyuan
authors.initials: Z
authors.lastname: Hu
authors.affiliation: Key laboratory of Horticultural Plant Growth, Development & Quality Improvement, Ministry of Agriculture, Hangzhou 310058, China. Key laboratory of Horticultural Plant Growth, Development & Quality Improvement, Ministry of Agriculture, Hangzhou 310058, China. Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Hangzhou 310058, China. yangjinghua@zju.edu.cn.
authors.forename: Jinghua
authors.initials: J
authors.lastname: Yang
authors.affiliation: Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou 310058, China. Key laboratory of Horticultural Plant Growth, Development & Quality Improvement, Ministry of Agriculture, Hangzhou 310058, China. Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Hangzhou 310058, China.
authors.forename: Mingfang
authors.initials: M
authors.lastname: Zhang
mesh_terms: D018506:Gene Expression Regulation, Plant; D015321:Gene Rearrangement; D020868:Gene Silencing; D054629:Genome, Mitochondrial; D018745:Genome, Plant; D009149:Mustard Plant / Q000235:genetics / Q000502:physiology*; D051479:Plant Infertility; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D010940:Plant Proteins
keywords: Cytoplasmic male sterility; DNA recombination; MSH1; mitochondrial DNA; pollen; substoichiometric shifting.