title: Cytosolic ascorbate peroxidase 2 (cAPX 2) is involved in the soybean response to flooding.
abstract: Proteomic analyses of soybean seedlings responding to flooding were conducted to identify key proteins involved. The seeds were germinated on a spongy matrix for two days, and then subjected to flooding for three days. After flooding, the total number of roots, the length of the main root, the lengths of the lateral and adventitious roots, and the fresh weight of the underground tissues of flooded soybean seedlings were significantly suppressed compared with nontreated plants. To identify the early flooding-responsive proteins, the seedling roots were used for preparing cytosolic and membrane fractions. After two-dimensional polyacrylamide gel electrophoresis and silver staining, 208 proteins were detected, and the levels of 44 were different from those of the control. The expression pattern of 10 proteins among the 44 from six different soybean cultivars confirmed that the 10 were flooding-responsive proteins. One of the 10 proteins was dominantly down-regulated under flooding conditions and was identified as cytosolic ascorbate peroxidase 2 (cAPX 2). Northern-hybridization showed that the abundance of cAPX 2 transcript decreased significantly after flooding, as did the enzymatic activity of APX. These results suggest that cAPX 2 is involved in flooding stress responses in young soybean seedlings.
authors.affiliation: National Institute of Crop Science, Kannondai 2-1-18, Tsukuba 305-8518, Japan.
authors.forename: Fang
authors.initials: F
authors.lastname: Shi
authors.forename: Ryo
authors.initials: R
authors.lastname: Yamamoto
authors.forename: Satoshi
authors.initials: S
authors.lastname: Shimamura
authors.forename: Susumu
authors.initials: S
authors.lastname: Hiraga
authors.forename: Norikazu
authors.initials: N
authors.lastname: Nakayama
authors.forename: Takuji
authors.initials: T
authors.lastname: Nakamura
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Yukawa
authors.forename: Mayumi
authors.initials: M
authors.lastname: Hachinohe
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Setsuko
authors.initials: S
authors.lastname: Komatsu
mesh_terms: D060387:Ascorbate Peroxidases; D015536:Down-Regulation; D055868:Floods; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000201:enzymology; D013025:Glycine max / Q000201:enzymology*; D013997:Time Factors; D014867:Water / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D014867:Water; D010544:Peroxidases; D060387:Ascorbate Peroxidases