ÿþ<HTML><HEAD><TITLE>25º Congresso Brasileiro de Microbiologia </TITLE><link rel=STYLESHEET type=text/css href=css.css></HEAD><BODY aLink=#ff0000 bgColor=#FFFFFF leftMargin=0 link=#000000 text=#000000 topMargin=0 vLink=#000000 marginheight=0 marginwidth=0><table align=center width=700 cellpadding=0 cellspacing=0><tr><td align=left bgcolor=#cccccc valign=top width=550><font face=arial size=2><strong><font face=Verdana, Arial, Helvetica, sans-serif size=3><font size=1>25º Congresso Brasileiro de Microbiologia </font></font></strong><font face=Verdana size=1><b><br></b></font><font face=Verdana, Arial,Helvetica, sans-serif size=1><strong> </strong></font></font></td><td align=right bgcolor=#cccccc valign=top width=150><font face=arial size=2><strong><font face=Verdana, Arial, Helvetica, sans-serif size=1><font size=1>ResumoID:909-1</font></em></font></strong></font></td></tr><tr><td colspan=2><br><br><table align=center width=700><tr><td>Área: <b>Ecologia Microbiana ( Divisão I )</b><p align=justify><strong>PRODUCTION REGULATION OF SECONDARY METABOLITES BY FUSARIC ACID AND THEIR ROLES IN SUPPRESSION OF <SPAN STYLE="FONT-STYLE: ITALIC;">FUSARIUM </SPAN>SPP.BY THE RHIZOBACTERIUM PSEUDOMONAS FLUORESCENS PF-5 </strong></p><p align=justify><b><u>Maria Carolina Quecine Quecine </u></b> (<i>ESALQ-USP</i>); <b>Teresa Kidarsa Kidarsa </b> (<i>USDA-ARS</i>); <b>Marcella D. Henkels Henkels </b> (<i>USDA-ARS</i>); <b>Brenda T. Shaffer Shaffer </b> (<i>USDA-ARS</i>); <b>Aline Aparecida Pizzirani-kleiner Pizzirani-kleiner </b> (<i>ESALQ-USP</i>); <b>Joyce Loper Loper </b> (<i>USDA-ARS</i>)<br><br></p><b><font size=2>Resumo</font></b><p align=justify class=tres><font size=2> <link rel="File-List" href="file:///C:%5CDOCUME%7E1%5Cmquecine%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml"><o:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place"></o:smarttagtype><o:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="State"></o:smarttagtype><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if !mso]><object classid="clsid:38481807-CA0E-42D2-BF39-B33AF135CC4D" id=ieooui></object> <style> st1:*{behavior:url(#ieooui) } </style> <![endif]--><style> <!-- /* Font Definitions */ @font-face {font-family:Calibri; panose-1:2 15 5 2 2 2 4 3 2 4; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:-1610611985 1073750139 0 0 159 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin-top:0in; margin-right:0in; margin-bottom:12.0pt; margin-left:0in; line-height:114%; mso-pagination:none; mso-layout-grid-align:none; punctuation-wrap:simple; font-size:11.0pt; font-family:Calibri; mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:Calibri; mso-font-kerning:14.0pt;} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> </style><!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} </style> <![endif]--> <p class="MsoNormal" style="text-align: justify; line-height: 200%;"><i><span style="font-family: Arial;">Pseudomonas fluorescens</span></i><span style="font-family: Arial;"> strain Pf-5 is a rhizosphere bacterium that acts as a biocontrol agent of soilborne plant diseases, and produces at least 10 different secondary metabolites including several with antifungal properties. Previously, other workers showed that the mycotoxin fusaric acid (FA), which is produced by many <i>Fusarium</i> spp., inhibited the production of 2,4-diacetylphoroglucinol (2,4-DAPG) by Pseudomonas spp. The goal of this study was to determine the role of Pf-5 metabolites in the suppression of<i> Fusarium</i> spp. and to investigate FA<i> </i>effects on secondary metabolite production. <span style="">&nbsp;</span>We derived site-directed mutants of Pf-5 with single and multiple mutations in the biosynthetic gene clusters for the antifungal metabolites 2,4-DAPG, pyrrolnitrin, pyoluteorin, hydrogen cyanide, rhizoxin, pyoverdine and enantio-pyochelin.<span style="">&nbsp; </span>These mutants were tested for suppression of the pathogens <i>Fusarium verticillioides</i> from corn and sugarcane and <i>Fusarium oxysporum</i> f. sp. <i>pisi</i> from pea. <i>Fusarium</i> spp. were similar, but not identical, in their sensitivity to Pf-5 metabolites. Rhizoxin and 2,4-DAPG were found to be primarily responsible for fungal antagonism by Pf-5 on several culture media.<span style="">&nbsp; </span>The influence of FA on secondary metabolism by Pf-5 was investigated using RT-qPCR and HPLC. Amendment of the culture medium with FA decreased 2,4-DAPG production and transcript levels of 2,4-DAPG biosynthetic genes. FA also influenced transcript abundance of pyoluteorin, rhizoxin, and pyoverdine biosynthesis genes. Similar results were confirmed by HPLC analysis. These results indicate that the mycotoxin influenced antibiotic production by Pf-5 at the transcriptional level. Our results demonstrated the importance of two compounds, rhizoxin and 2,4-DAPG, in suppression of <i>Fusarium</i> spp. by Pf-5, and confirmed that an inter-species signaling system mediated by FA influenced secondary metabolites production by the bacterial biological control organism.<o:p></o:p></span></p> <p class="MsoNormal" style="text-align: justify; line-height: 200%;"><span style="font-family: Arial;">Financial Support: State of <st1:state w:st="on"><st1:place w:st="on">São</st1:place></st1:state> Paulo Research Foundation  FAPESP 05-53748-6 and National Research Initiative Competitive Grants 2006-35319-17427 from USDA-CSREES.<o:p></o:p></span></p> </font></p><br><b>Palavras-chave: </b>&nbsp;Pseudomonas fluorescens, Fusarium spp., secondary metabolites, fusaric acid, biological control</td></tr></table></tr></td></table></body></html>