title: Molecular cloning and functional analysis of a novel type of Bowman-Birk inhibitor gene family in rice.
abstract: Bowman-Birk inhibitor (BBI) genes encode serine protease inhibitors that have repetitive cysteine-rich domains with reactive sites for the trypsin or chymotrypsin family. We have identified seven BBI genes from japonica rice (Oryza sativa subsp. japonica var Teqing). All of the genes identified were found in a single cluster on the southern end of the long arm of rice chromosome 1. Four of the seven BBI genes have two repetitive cysteine-rich domains, whereas one has a truncated domain with only one reactive site. We have also identified three novel BBI genes, each of which possesses three repetitive domains instead of two. In situ hybridization analyses indicated that the accumulation of rice BBI transcripts was differentially regulated in germinating embryos and also in the leaves, roots, and flower organs at later developmental stages. Different members of the rice BBI gene family displayed different expression patterns during rice seed germination, and wounding induced the expression of rice BBI transcripts. The three-domain BBIs had higher expression levels than the two-domain BBIs. It was also found that the mRNA of rice BBI genes was present in abundant amounts in scutellar epithelium and aleurone layer cells. RBBI3-1, one of the three-domain RBBI, exhibited in vitro trypsin-inhibiting activity but no chymotrypsin-inhibiting activity. Overexpression of RBBI2-3 in transgenic rice plants resulted in resistance to the fungal pathogen Pyricularia oryzae, indicating that proteinase inhibitors confer resistance against the fungal pathogen in vivo and that they might play a role in the defense system of the rice plant.
authors.affiliation: Peking-Yale Joint Center for Plant Molecular Genetics and Agro-Biotechnology, National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Li-Jia
authors.initials: LJ
authors.lastname: Qu
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.forename: Meihua
authors.initials: M
authors.lastname: Liu
authors.forename: Naisui
authors.initials: N
authors.lastname: Pan
authors.forename: Haruko
authors.initials: H
authors.lastname: Okamoto
authors.forename: Zhongzhuan
authors.initials: Z
authors.lastname: Lin
authors.forename: Chengyun
authors.initials: C
authors.lastname: Li
authors.forename: Donghui
authors.initials: D
authors.lastname: Li
authors.forename: Jinling
authors.initials: J
authors.lastname: Wang
authors.forename: Guofeng
authors.initials: G
authors.lastname: Zhu
authors.forename: Xin
authors.initials: X
authors.lastname: Zhao
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.forename: Hongya
authors.initials: H
authors.lastname: Gu
authors.forename: Zhangliang
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D017343:Genes, Plant; D018745:Genome, Plant; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D005810:Multigene Family; D012275:Oryza / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014361:Trypsin Inhibitors / Q000235:genetics
chemical_list: D010940:Plant Proteins; D014361:Trypsin Inhibitors