Novel bifunctional nucleases, OmBBD and AtBBD1, are involved in abscisic acid-mediated callose deposition in Arabidopsis.
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.
You
Min Kyoung
MK
School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea.
Shin
Hyun Young
HY
Kim
Young Jin
YJ
Ok
Sung Han
SH
Cho
Sung Ki
SK
Jeung
Ji Ung
JU
Yoo
Sang Dong
SD
Kim
Jeong Kook
JK
Shin
Jeong Sheop
JS
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
D018744:DNA, Plant; D005936:Glucans; D000040:Abscisic Acid; C048306:callose; D003851:Deoxyribonucleases; D012260:Ribonucleases