title: Novel bifunctional nucleases, OmBBD and AtBBD1, are involved in abscisic acid-mediated callose deposition in Arabidopsis.
abstract: Screening of the expressed sequence tag library of the wild rice species Oryza minuta revealed an unknown gene that was rapidly and strongly induced in response to attack by a rice fungal pathogen (Magnaporthe oryzae) and an insect (Nilaparvata lugens) and by wounding, abscisic acid (ABA), and methyl jasmonate treatments. Its recombinant protein was identified as a bifunctional nuclease with both RNase and DNase activities in vitro. This gene was designated OmBBD (for O. minuta bifunctional nuclease in basal defense response). Overexpression of OmBBD in an Arabidopsis (Arabidopsis thaliana) model system caused the constitutive expression of the PDF1.2, ABA1, and AtSAC1 genes, which are involved in priming ABA-mediated callose deposition. This activation of defense responses led to an increased resistance against Botrytis cinerea. atbbd1, the knockout mutant of the Arabidopsis ortholog AtBBD1, was susceptible to attack by B. cinerea and had deficient callose deposition. Overexpression of either OmBBD or AtBBD1 in atbbd1 plants complemented the susceptible phenotype of atbbd1 against B. cinerea as well as the deficiency of callose deposition. We suggest that OmBBD and AtBBD1 have a novel regulatory role in ABA-mediated callose deposition.
authors.affiliation: School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea.
authors.forename: Min Kyoung
authors.initials: MK
authors.lastname: You
authors.forename: Hyun Young
authors.initials: HY
authors.lastname: Shin
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Sung Han
authors.initials: SH
authors.lastname: Ok
authors.forename: Sung Ki
authors.initials: SK
authors.lastname: Cho
authors.forename: Ji Ung
authors.initials: JU
authors.lastname: Jeung
authors.forename: Sang Dong
authors.initials: SD
authors.lastname: Yoo
authors.forename: Jeong Kook
authors.initials: JK
authors.lastname: Kim
authors.forename: Jeong Sheop
authors.initials: JS
authors.lastname: Shin
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D020171:Botrytis; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000235:genetics; D003851:Deoxyribonucleases / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D005936:Glucans / Q000378:metabolism*; D020082:Magnaporthe; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D012260:Ribonucleases / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D018744:DNA, Plant; D005936:Glucans; D000040:Abscisic Acid; C048306:callose; D003851:Deoxyribonucleases; D012260:Ribonucleases