OsTGAP1, a bZIP Transcription Factor, Coordinately Regulates the Inductive Production of Diterpenoid Phytoalexins in Rice

Production of major diterpenoid phytoalexins, momilactones and phytocassanes, is induced in rice upon recognition of pathogenic invasion as plant defense-related compounds. We recently showed that biosynthetic genes for momilactones are clustered on rice chromosome 4 and co-expressed after elicitation, mimicking pathogen attack. Because genes for most metabolic pathways in plants are not organized in gene clusters, examination of the mechanism(s) regulating the expression of such clustered genes is needed. Here, we report a chitin oligosaccharide elicitor-inducible basic leucine zipper transcription factor, OsTGAP1, which is essential for momilactone biosynthesis and regulates the expression of the five genes in the cluster. The knock-out mutant for OsTGAP1 had almost no expression of the five clustered genes (OsCPS4, OsKSL4, CYP99A2, CYP99A3, and OsMAS) or production of momilactones upon elicitor treatment. Inductive expression of OsKSL7 for phytocassane biosynthesis was also largely affected in the ostgap1 mutant, although phytocassane accumulation still occurred. Conversely, OsTGAP1-overexpressing lines exhibited enhanced expression of the clustered genes and hyperaccumulation of momilactones in response to the elicitor. Furthermore, enhanced expression of OsKSL7 and hyperaccumulation of phytocassanes was also observed. We also found that OsTGAP1 overexpression can influence transcriptional up-regulation of OsDXS3 in the methylerythritol phosphate pathway, eventually leading to inductive production of diterpenoid phytoalexins. These results indicate that OsTGAP1 functions as a key regulator of the coordinated transcription of genes involved in inductive diterpenoid phytoalexin production in rice and mainly exerts an essential role on expression of the clustered genes for momilactone biosynthesis. Production of major diterpenoid phytoalexins, momilactones and phytocassanes, is induced in rice upon recognition of pathogenic invasion as plant defense-related compounds. We recently showed that biosynthetic genes for momilactones are clustered on rice chromosome 4 and co-expressed after elicitation, mimicking pathogen attack. Because genes for most metabolic pathways in plants are not organized in gene clusters, examination of the mechanism(s) regulating the expression of such clustered genes is needed. Here, we report a chitin oligosaccharide elicitor-inducible basic leucine zipper transcription factor, OsTGAP1, which is essential for momilactone biosynthesis and regulates the expression of the five genes in the cluster. The knock-out mutant for OsTGAP1 had almost no expression of the five clustered genes (OsCPS4, OsKSL4, CYP99A2, CYP99A3, and OsMAS) or production of momilactones upon elicitor treatment. Inductive expression of OsKSL7 for phytocassane biosynthesis was also largely affected in the ostgap1 mutant, although phytocassane accumulation still occurred. Conversely, OsTGAP1-overexpressing lines exhibited enhanced expression of the clustered genes and hyperaccumulation of momilactones in response to the elicitor. Furthermore, enhanced expression of OsKSL7 and hyperaccumulation of phytocassanes was also observed. We also found that OsTGAP1 overexpression can influence transcriptional up-regulation of OsDXS3 in the methylerythritol phosphate pathway, eventually leading to inductive production of diterpenoid phytoalexins. These results indicate that OsTGAP1 functions as a key regulator of the coordinated transcription of genes involved in inductive diterpenoid phytoalexin production in rice and mainly exerts an essential role on expression of the clustered genes for momilactone biosynthesis. Plants attacked by pathogenic microorganisms respond with a variety of defensive reactions, including the production of antimicrobial secondary metabolites known as phytoalexins (1VanEtten H.D. Mansfield J.W. Bailey J.A. Farmer E.E. Plant Cell. 1994; 6: 1191-1192Crossref PubMed Google Scholar). These compounds are transiently generated in response to signal molecules called elicitors, which are usually derived from pathogens. In rice, 14 diterpenoid phytoalexins have been identified to date in suspension-cultured cells treated with biotic elicitors, such as chitin oligosaccharide, and in leaves infected with the blast fungus Magnaporthe grisea or irradiated with UV light. Phytoalexins can be classified into four groups, based on the structure of their hydrocarbon precursors: phytocassanes A–E, oryzalexins A–F, momilactones A and B, and oryzalexin S (2Koga J. Shimura M. Oshima K. Ogawa N. Yamauchi T. Ogasawara N. 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Tetrahedron. 1993; 49: 2025-2032Crossref Scopus (62) Google Scholar). Geranylgeranyl diphosphate, a common precursor of diterpenoid phytoalexins, is first cyclized by OsCPS2/OsCyc2 and OsCPS4/OsCyc1 to yield ent-copalyl diphosphate and syn-copalyl diphosphate (11Otomo K. Kenmoku H. Oikawa H. König W.A. Toshima H. Mitsuhashi W. Yamane H. Sassa T. Toyomasu T. Plant J. 2004; 39: 886-893Crossref PubMed Scopus (140) Google Scholar, 12Sakamoto T. Miura K. Itoh H. Tatsumi T. Ueguchi-Tanaka M. Ishiyama K. Kobayashi M. Agrawal G.K. Takeda S. Abe K. Miyao A. Hirochika H. Kitano H. Ashikari M. Matsuoka M. Plant Physiol. 2004; 134: 1642-1653Crossref PubMed Scopus (525) Google Scholar). Next, OsKSL7/OsDTC1, OsKSL10, OsKSL4, and OsKSL8/OsDTC2 catalyze the second cyclization of ent-copalyl diphosphate or syn-copalyl diphosphate to four distinct diterpene hydrocarbons: ent-cassa-12,15-diene, ent-sandaracopimaradiene, 9βH-pimara-7,15-diene, and stemar-13-ene, respectively (13Cho E.M. Okada A. Kenmoku H. Otomo K. Toyomasu T. Mitsuhashi W. Sassa T. Yajima A. Yabuta G. Mori K. Oikawa H. Toshima H. Shibuya N. Nojiri H. Omori T. Nishiyama M. Yamane H. Plant J. 2004; 37: 1-8Crossref PubMed Scopus (89) Google Scholar, 14Nemoto T. Cho E.M. Okada A. Okada K. Otomo K. Kanno Y. Toyomasu T. Mitsuhashi W. Sassa T. Minami E. Shibuya N. Nishiyama M. Nojiri H. Yamane H. FEBS Lett. 2004; 571: 182-186Crossref PubMed Scopus (58) Google Scholar, 15Peters R.J. Phytochemistry. 2006; 67: 2307-2317Crossref PubMed Scopus (150) Google Scholar). For momilactone biosynthesis, two cytochrome P450 monooxygenase (P450) genes (CYP99A2 and CYP99A3) and a dehydrogenase gene (OsMAS) are also involved in the downstream oxidation steps of the diterpene hydrocarbons. Intriguingly, five genes for momilactone biosynthesis are localized in a narrow region of chromosome 4, creating a functional gene cluster (Fig. 1) (16Shimura K. Okada A. Okada K. Jikumaru Y. Ko K.W. Toyomasu T. Sassa T. Hasegawa M. Kodama O. Shibuya N. Koga J. Nojiri H. Yamane H. J. Biol. Chem. 2007; 282: 34013-34018Abstract Full Text Full Text PDF PubMed Scopus (204) Google Scholar). Genes for most metabolic pathways in plants are not organized in gene clusters. However, there are some examples of gene clusters for the biosynthesis of isoprenoids and plant defense compounds other than momilactones in rice. For example, the genes responsible for the biosynthesis of thalianol in Arabidopsis, benzoxazinoids in maize, and avenacins in oat are all organized in clusters (17Qi X. Bakht S. Leggett M. Maxwell C. Melton R. Osbourn A. Proc. Natl. Acad. Sci. U.S.A. 2004; 101: 8233-8238Crossref PubMed Scopus (226) Google Scholar, 18Field B. Osbourn A.E. Science. 2008; 320: 543-547Crossref PubMed Scopus (302) Google Scholar, 19Frey M. Chomet P. Glawischnig E. Stettner C. Grün S. Winklmair A. Eisenreich W. Bacher A. Meeley R.B. Briggs S.P. Simcox K. Gierl A. Science. 1997; 277: 696-699Crossref PubMed Scopus (507) Google Scholar). The spatial expression of the avenacin biosynthetic genes is tightly regulated and occurs only in the root epidermis, the site of accumulation of the end product (20Qi X. Bakht S. Qin B. Leggett M. Hemmings A. Mellon F. Eagles J. Werck-Reichhart D. Schaller H. Lesot A. Melton R. Osbourn A. Proc. Natl. Acad. Sci. U.S.A. 2006; 103: 18848-18853Crossref PubMed Scopus (146) Google Scholar). In contrast, the rice momilactone biosynthetic gene cluster exhibits a temporally coordinated expression pattern of mRNAs, peaking at 6–12 h after elicitor treatment of rice cell suspension cultures (11Otomo K. Kenmoku H. Oikawa H. König W.A. Toshima H. Mitsuhashi W. Yamane H. Sassa T. Toyomasu T. Plant J. 2004; 39: 886-893Crossref PubMed Scopus (140) Google Scholar, 21Okada A. Shimizu T. Okada K. Kuzuyama T. Koga J. Shibuya N. Nojiri H. Yamane H. Plant Mol. Biol. 2007; 65: 177-187Crossref PubMed Scopus (107) Google Scholar). Such coordinated, stress-inducible clustered gene expression, responsible for the biosynthesis of one particular compound, has not previously been reported in plants. Thus, it is interesting to examine the mechanism(s) regulating the coordinated expression of the momilactone biosynthetic gene cluster. Here, we report the identification of an elicitor-inducible basic leucine zipper (bZIP) 3The abbreviations used are: bZIPbasic leucine zipperMEPmethylerythritol phosphateRTreverse transcriptionqRTquantitative reverse transcriptionGSTglutathione S-transferaseGCgas chromatographyMSmass spectrometryLCliquid chromatographyLUCluciferaseTGATGACG-sequence-specific binding protein. 3The abbreviations used are: bZIPbasic leucine zipperMEPmethylerythritol phosphateRTreverse transcriptionqRTquantitative reverse transcriptionGSTglutathione S-transferaseGCgas chromatographyMSmass spectrometryLCliquid chromatographyLUCluciferaseTGATGACG-sequence-specific binding protein. transcription factor, OsTGAP1, which is essential for the biosynthesis of momilactone in rice and which coordinately regulates the expression of all five genes in the cluster. We also show that OsTGAP1 can influence the expression of a phytocassane biosynthetic gene and the upstream methylerythritol phosphate (MEP) pathway gene, leading to production of phytocassanes. These results indicate that OsTGAP1 functions as a key regulator of the coordinated transcription of genes involved in inductive diterpenoid phytoalexins production in rice. basic leucine zipper methylerythritol phosphate reverse transcription quantitative reverse transcription glutathione S-transferase gas chromatography mass spectrometry liquid chromatography luciferase TGACG-sequence-specific binding protein. basic leucine zipper methylerythritol phosphate reverse transcription quantitative reverse transcription glutathione S-transferase gas chromatography mass spectrometry liquid chromatography luciferase TGACG-sequence-specific binding protein. Purified chitooctaose (Yaizu Suisankagaku Industry Co., Ltd., Tokyo, Japan) was re-N-acetylated to give N-acetylchitooctaose, as described (22Ito Y. Kaku H. Shibuya N. Plant J. 1997; 12: 347-356Crossref PubMed Scopus (131) Google Scholar), and used as a chitin oligosaccharide elicitor throughout this study. Oryza sativa L. cv. Nipponbare was used as the wild type. Calli of O. sativa L. cv. Nipponbare were cultured as described previously (13Cho E.M. Okada A. Kenmoku H. Otomo K. Toyomasu T. Mitsuhashi W. Sassa T. Yajima A. Yabuta G. Mori K. Oikawa H. Toshima H. Shibuya N. Nojiri H. Omori T. Nishiyama M. Yamane H. Plant J. 2004; 37: 1-8Crossref PubMed Scopus (89) Google Scholar). Six days after transfer to fresh culture medium, the cultured rice cells were used for assays with a chitin oligosaccharide elicitor treatment (N-acetylchitooctaose, 1 ppm) throughout this study. Tos17-inserted mutants of H0155 (for AK073715) and NC0005 (for AK102690) were obtained from the National Institute of Agrobiological Sciences of Japan (Tos17 mutant panel project; available on the World Wide Web). The insertion site of Tos17 is indicated in supplemental Fig. S2A. The Tos17 homozygous mutants were selected by PCR genotyping, and generated cultured cells of the mutant were used for the experiments. The OsKSL4 promoter fragments were amplified by PCR, using genomic DNA prepared from suspension-cultured rice cells (cv. Nipponbare) as template. The mutated constructs were generated via a two-step PCR process (primer overlapping mutagenesis), and the core TGAC sequence was converted to CCTA. The OsKSL4 promoter and mutated constructs were into the and of the basic the luciferase gene For the OsTGAP1 sequence was amplified using OsTGAP1 obtained from the The OsTGAP1 was to the of the transcription to the which is the of a promoter of the binding site was used as a M. M. A. T. 67: PubMed Scopus Google Scholar). For the production of and the of the OsTGAP1 sequence was into For the was by into and into The was also into T. T. T. K. M. Y. K. Matsuoka K. T. T. J. 2007; PubMed Scopus Google and used for rice cells by as described by Kaku H. Y. N. C. N. K. Minami E. Shibuya N. Proc. Natl. Acad. Sci. U.S.A. 2006; 103: PubMed Scopus Google Scholar). of was by and with an and were used to the of For the a reverse and Tokyo, Japan) were was using on an PCR from were using the in and the results were as to the expression of as described previously A. Shimizu T. Okada K. Kuzuyama T. Koga J. Shibuya N. Nojiri H. Yamane H. Plant Mol. Biol. 2007; 65: 177-187Crossref PubMed Scopus (107) Google Scholar). was with the to the rice days after transfer to fresh culture medium, were used for The OsKSL4 was in a with the and 1 of DNA was into the rice cells the were in with or for h at in and in cell The and was using a Tokyo, Japan) to the the after the of was the upstream of OsKSL4 were and The OsTGAP1 was in E. as a glutathione S-transferase The E. a for the expression of was cultured in The was on and used for fragments were amplified by PCR using the (for or the (for mutated as template. assays were using a second to the were from suspension-cultured rice cells using and by gas spectrometry as described previously (13Cho E.M. Okada A. Kenmoku H. Otomo K. Toyomasu T. Mitsuhashi W. Sassa T. Yajima A. Yabuta G. Mori K. Oikawa H. Toshima H. Shibuya N. Nojiri H. Omori T. Nishiyama M. Yamane H. Plant J. 2004; 37: 1-8Crossref PubMed Scopus (89) Google Scholar). Phytoalexins were from suspension-cultured rice cells after and by liquid mass spectrometry as described previously T. Jikumaru Y. Okada A. Okada K. Koga J. K. Minami E. Shibuya N. Hasegawa M. Kodama O. Nojiri H. Yamane H. Phytochemistry. 2008; PubMed Scopus (58) Google Scholar). The used for genotyping, and are in supplemental regulating for momilactone biosynthesis, we first a chitin oligosaccharide elicitor-inducible promoter a region upstream of the OsKSL4 gene, responsible for the first to momilactone biosynthesis, using a Fig. that from to and to the promoter of to the elicitor. A for known recognition for transcription in the region and the of two that are known to be by transcription including E. Plant Cell. PubMed Scopus Google Scholar), and two TGAC which are recognition for transcription T. S. Plant Sci. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). These were to (Fig. of the promoter identified a in the region from to upstream of the site of OsKSL4 as a for the elicitor-inducible expression of OsKSL4 (Fig. that a transcription was involved in the We on elicitor-inducible transcription with expression to that of OsKSL4 or to the OsKSL4 gene by the elicitor treatment A. Shimizu T. Okada K. Kuzuyama T. Koga J. Shibuya N. Nojiri H. Yamane H. Plant Mol. Biol. 2007; 65: 177-187Crossref PubMed Scopus (107) Google Scholar). than transcription of transcription genes were based on their expression after elicitor treatment (Fig. the and were transcription the of Fig. can to the and are involved in defense E. P. L. S. J. E. Plant J. PubMed Google Scholar). Thus, we transcription as to OsKSL4 gene of genes by that the gene was induced 4 h after elicitor treatment than expression to by and the gene was induced for h after to OsKSL4 (Fig. We not expression of the gene and it as a that the product was to the and and and that the product was classified in the Fig. is to the involved in of transcription J. PubMed Scopus Google Scholar), and is involved in defense M. J. X. Plant Physiol. 2007; PubMed Scopus Google Scholar), the of is still of the and was using as a (Fig. Thus, we on the and genes to were responsible for the expression of We used the rice Tos17 insertion mutants H0155 (for AK073715) and NC0005 (for AK102690) to examine their mutants obtained from the the Tos17 insertion in the first of and the of Fig. H. Plant Mol. Biol. 1997; PubMed Google Scholar, H. Plant Biol. PubMed Scopus Google Scholar, A. Y. Kitano H. Itoh J. M. K. O. Y. Hirochika H. Plant Mol. Biol. 2007; PubMed Scopus Google Scholar). were to be expression in response to Fig. of phytoalexins in the culture and h after elicitor treatment that the of momilactones in H0155 mutant cells to than of that in cells (Fig. the phytocassanes were almost the the mutant and cells at the phytocassanes were than that in cells at h in the H0155 mutant (Fig. The inductive expression of OsKSL4 after was in the H0155 mutant with cells (Fig. The inductive expression of OsKSL7 after the in cells was also in the H0155 mutant, the expression at h and h after the were than that of cells (Fig. In to expression of genes for phytoalexin biosynthesis, the upstream gene expression responsible for diphosphate production was also in the H0155 The expression of OsDXS3 in rice, which phosphate involved in the first in the pathway in was in the H0155 mutant (Fig. of diterpene after that accumulation of 9βH-pimara-7,15-diene, a precursor for was only in the accumulation of ent-cassa-12,15-diene, a precursor for phytocassanes, was to the in the H0155 mutant and cells (Fig. These results that is essential for the momilactone biosynthesis the up-regulation of OsKSL4 gene expression and has a role in of OsKSL7 and OsDXS3 expression induced by elicitor which to production of phytocassanes after the elicitor the gene was OsTGAP1 sativa for phytoalexin production In the NC0005 mutant, diterpenoid phytoalexin production and the biosynthetic gene expression were with that in cells Fig. that is to be involved in regulating phytoalexin biosynthesis. assays that OsTGAP1 the DNA the region in the OsKSL4 in a (Fig. We also found that OsTGAP1 as a transcriptional using a in which the binding sequence is to as a and the is to OsTGAP1 as an (Fig. the of we that OsTGAP1 regulates momilactone biosynthesis of OsKSL4 expression, by binding to the in the OsKSL4 the in which OsTGAP1 regulates expression of phytoalexin biosynthetic rice plants OsTGAP1 to a were generated (Fig. In accumulation of momilactones was by (Fig. Furthermore, OsTGAP1-overexpressing lines had enhanced accumulation of momilactones with cells after treatment with elicitor (Fig. accumulation of phytocassanes in the was (Fig. the was treated with the enhanced accumulation of phytocassanes was also in the lines as in hyperaccumulation of momilactones (Fig. The of phytoalexins with the expression of the not OsKSL4, and OsDXS3 expression in the OsTGAP1-overexpressing lines was by the lines exhibited induced expression of genes (Fig. a of expression was in the cells with cells h after elicitation, with the hyperaccumulation of momilactones and phytocassanes in of expression of genes were for at h after in the lines (Fig. These results that OsTGAP1 can influence the biosynthetic pathway for diterpenoid phytoalexins, including the upstream pathway, at a transcriptional eventually leading to production of a of the diterpenoid phytoalexins. previously the momilactone biosynthetic genes are organized in a gene coordinated, expression upon elicitor treatment. OsTGAP1 overexpression to production of momilactones elicitation, that the five momilactone biosynthetic including OsKSL4, be coordinately regulated by we expression of the genes in the momilactone biosynthetic gene cluster in the ostgap1 mutant and the expression of the five momilactone biosynthetic genes (OsCPS4, OsKSL4, CYP99A2, CYP99A3, and OsMAS) was in ostgap1 expression of the gene and the gene of which are the were (Fig. The clustered not the were in the cells by an elicitor (Fig. The results indicate that clustered genes for momilactone biosynthesis are coordinately regulated by In this we identified an elicitor-inducible rice transcription factor, OsTGAP1, which is essential for elicitor-inducible production of momilactones and which coordinately regulates the expression of all five genes in the momilactone biosynthetic gene cluster. OsTGAP1 was also to be involved in the transcriptional of OsKSL7 for phytocassane biosynthesis and OsDXS3 in the that OsTGAP1 can influence momilactone and phytocassane production up-regulation of the biosynthetic genes and the upstream pathway gene the elicitor treatment. OsTGAP1 expression is induced by treatment with a chitin oligosaccharide OsTGAP1 be a regulator that the expression of biosynthetic genes and upstream pathway genes for diterpenoid phytoalexin production as of the defensive the of a chitin oligosaccharide elicitor H. Y. N. C. N. K. Minami E. Shibuya N. Proc. Natl. Acad. Sci. U.S.A. 2006; 103: PubMed Scopus Google Scholar). In Arabidopsis, genes that the phytoalexin are coordinately and their expression is the of an key transcription D. Y. L. G. J. S. Proc. Natl. Acad. Sci. U.S.A. 2008; PubMed Scopus Google Scholar). the transcription which regulates the expression of the two P450 genes and involved in biosynthesis, has been reported K. S. K. S. J. P. O. J. J. M. J. 2008; PubMed Scopus Google Scholar), a key transcription that is involved in the coordinated up-regulation of biosynthetic genes is still the and genes are not in a gene cluster. Thus, such a of OsTGAP1 in regulating chitin expression of the momilactone biosynthetic gene cluster to be of rice plants. showed that OsTGAP1 is to the including which has been to in M. J. X. Plant Physiol. 2007; PubMed Scopus Google Scholar). The that OsTGAP1 in the defensive response in rice. a of a using the and the Oryza available on the World Wide at transcription genes are in rice. only including OsTGAP1, were selected as elicitor by Thus, to narrow the elicitor-inducible regulating the OsKSL4 expression using the was in this We used the rice Tos17 insertion mutant H0155 for of a of H0155 has not been the of the mutant is most to a of the OsTGAP1 four homozygous plants that we by of a all exhibited the momilactone showed that OsTGAP1 was responsible for elicitor-inducible production of momilactones and the expression of the biosynthetic Because accumulation of momilactones h after the elicitation, not phytocassanes, was affected by the OsTGAP1 OsTGAP1 was to a influence on momilactone biosynthetic gene in OsKSL4 gene expression was to h after in the ostgap1 mutant, OsKSL7 expression in the mutant was still h after the elicitation, which was with the expression in the of OsKSL7 expression was in the mutant the of OsKSL7 expression in the ostgap1 mutant is at this OsKSL7 expression with up-regulation is with the accumulation of phytocassanes in the ostgap1 mutant (Fig. 4, and to expression of OsDXS3 in the upstream pathway, of OsDXS3 gene expression was in the ostgap1 mutant after Thus, the inductive expression of momilactone biosynthetic genes to be regulated by OsTGAP1 in a from that of and OsDXS3 gene The ostgap1 mutant also showed that all five genes for momilactone biosynthesis in the cluster were regulated by OsTGAP1 upon elicitor expression of genes of the cluster and was of the clustered genes for momilactone biosynthesis by OsTGAP1 was also using These results that the OsTGAP1 has a on regulating the gene cluster for momilactone biosynthesis. We found that OsTGAP1 overexpression can also influence transcriptional up-regulation of the phytocassane biosynthetic gene and the pathway gene elicitation, eventually leading to diterpene phytoalexin OsTGAP1 was to as a transcriptional (Fig. OsTGAP1 be to influence expression of genes by binding to their In can be found in the promoter of OsKSL7 and OsDXS3 Fig. the binding of OsTGAP1 to the to be the that OsTGAP1 be the regulator for the production of diterpenoid phytoalexins and phytoalexin biosynthetic genes and the upstream pathway gene responsible for diphosphate, the precursor of diterpene phytoalexins, after elicitor OsTGAP1 expression of the clustered genes for momilactone biosynthesis also be A of in the region the clustered genes than that be by However, we also found that a of in other from the momilactone cluster in that the promoter of not only the five momilactone biosynthetic genes also genes Fig. OsTGAP1 to the promoter of all clustered genes to their expression, it is also that OsTGAP1 regulates expression of the clustered genes for momilactone biosynthesis by other than binding to all in promoter of the clustered of on the momilactone biosynthetic gene cluster be the leading to of the of also that OsTGAP1 was not to the expression of genes for diterpenoid phytoalexin biosynthesis. that a of OsTGAP1 the of an that functions with OsTGAP1 upon elicitor treatment can the of biosynthetic gene expression (Fig. of has been to the of this C. C. A. R. T. D. Plant Cell. PubMed Scopus Google and also a to OsTGAP1 However, that are involved in are not in OsTGAP1 Fig. that this is not the for OsTGAP1 of which are to gene expression for diterpenoid phytoalexin biosynthesis with OsTGAP1, for the of the in which OsTGAP1 coordinately all genes involved in diterpenoid phytoalexin including the momilactone biosynthetic gene is results for the of an coordinated by OsTGAP1 to defensive compounds in rice. We M. and M. for the T. for the and Y. and H. Hirochika for rice and Tos17 mutant We also A. Osbourn for the with