title: RhMKK9, a rose MAP KINASE KINASE gene, is involved in rehydration-triggered ethylene production in rose gynoecia.
abstract: Flower opening is an important process in the life cycle of flowering plants and is influenced by various endogenous and environmental factors. Our previous work demonstrated that rose (Rosa hybrida) flowers are highly sensitive to dehydration during flower opening and the water recovery process after dehydration induced ethylene production rapidly in flower gynoecia. In addition, this temporal- and spatial-specific ethylene production is attributed to a transient but robust activation of the rose MAP KINASE6-ACC SYNTHASE1 (RhMPK6-RhACS1) cascade in gynoecia. However, the upstream component of RhMPK6-RhACS1 is unknown, although RhMKK9 (MAP KINASE KINASE9), a rose homologue of Arabidopsis MKK9, could activate RhMPK6 in vitro. In this study, we monitored RhMKK2/4/5/9 expression, the potential upstream kinase to RhMPK6, in rose gynoecia during dehydration and rehydration.
  
  
  
  We found only RhMKK9 was rapidly and strongly induced by rehydration. Silencing of RhMKK9 significantly decreased rehydration-triggered ethylene production. Consistently, the expression of several ethylene-responsive genes was down regulated in the petals of RhMKK9-silenced flowers. Moreover, we detected the DNA methylation level in the promoter and gene body of RhMKK9 by Chop-PCR. The results showed that rehydration specifically elevated the DNA methylation level on the RhMKK9 gene body, whereas it resulted in hypomethylation in its promoter.
  
  
  
  Our results showed that RhMKK9 possibly acts as the upstream component of the RhMKK9-RhMPK6-RhACS1 cascade and is responsible for water recovery-triggered ethylene production in rose gynoecia, and epigenetic DNA methylation is involved in the regulation of RhMKK9 expression by rehydration.
authors.affiliation: Department of Ornamental Horticulture, China Agricultural University, Beijing, 100193, China.|Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.
authors.forename: Jiwei
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Ornamental Horticulture, China Agricultural University, Beijing, 100193, China.|Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Flower Research Institute, Yunnan Academy of Agricultural Sciences, Kunming, 650205, China.
authors.forename: Qigang
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Ornamental Horticulture, China Agricultural University, Beijing, 100193, China.|Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Feng
authors.affiliation: Department of Ornamental Horticulture, China Agricultural University, Beijing, 100193, China.|Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Ornamental Horticulture, China Agricultural University, Beijing, 100193, China.|College of Biology and Environmental Engineering, Provincial Key Laboratory of Biocontrol, Guiyang University, Guiyang, 550005, China.
authors.forename: Yonglu
authors.initials: Y
authors.lastname: Meng
authors.affiliation: Department of Ornamental Horticulture, China Agricultural University, Beijing, 100193, China.|Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Ornamental Horticulture, China Agricultural University, Beijing, 100193, China.|Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.
authors.forename: Guoqin
authors.initials: G
authors.lastname: Liu
authors.affiliation: Department of Ornamental Horticulture, China Agricultural University, Beijing, 100193, China.|Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Ma
authors.affiliation: College of Horticulture and Landscape, University, Yunnan Agricultural University, Kunming, 650201, China.
authors.forename: Hongzhi
authors.initials: H
authors.lastname: Wu
authors.affiliation: Department of Ornamental Horticulture, China Agricultural University, Beijing, 100193, China.|Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.
authors.forename: Junping
authors.initials: J
authors.lastname: Gao
authors.affiliation: Department of Ornamental Horticulture, China Agricultural University, Beijing, 100193, China. ma_nan@cau.edu.cn.|Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China. ma_nan@cau.edu.cn.
authors.forename: Nan
authors.initials: N
authors.lastname: Ma
mesh_terms: D005030:Ethylenes / Q000096:biosynthesis*; D035264:Flowers / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D005810:Multigene Family; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D027826:Rosa / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D005030:Ethylenes; D010940:Plant Proteins; C036216:ethylene; D020929:Mitogen-Activated Protein Kinase Kinases
keywords: DNA methylation; Ethylene biosynthesis; Gynoecia; Rehydration; RhMKK9; Rose flower