Abstract
BackgroundAspartic protease (APs) plays important roles in plant growth, development and biotic and abiotic stresses. We previously reported that the expression of a rice AP gene (OsAP77, Os10g0537800) was induced by probenazole (PBZ), a chemical inducer of disease resistance. In this study we examined some characteristics of this gene in response to fungal, bacterial and viral pathogens.ResultsTo elucidate the spatial and temporal expression of OsAP77, the chimeric gene was constructed carrying the structural gene encoding β-glucuronidase (GUS) driven by the OsAP77 promoter. This construct was introduced into rice and the transgenic lines were tested to analyze gene expression by fungal, bacterial and viral infections. Inoculation with Magnaporthe oryzae or Xanthomonas oryzae pv. oryzae revealed the enhanced GUS activities in vascular tissues surrounding the symptom sites by each pathogen. Moreover, GUS activity also increased after inoculation with Cucumber mosaic virus (CMV). Transgenic plants immersed in a solution containing salicylic acid (SA), isonicotinic acid (INA), hydrogen peroxide (H2O2) or abscisic acid (ABA) showed an increased level of GUS activity exclusively in vascular tissues. RT-PCR analysis showed that OsAP77 was induced not only by infection with these pathogens, but also after treatment with SA, INA, H2O2 or ABA. A knockout mutant line of OsAP77 by the insertion of Tos17 after inoculation with M. oryzae, X. oryzae pv. oryzae or CMV showed an enhanced susceptibility compared to wild type.ConclusionThese results suggest that the expression of OsAP77 is induced by pathogen infection and defense related signaling molecules in a vascular tissue specific manner and that this gene has a positive role of defense response against fungal, bacterial and viral infections.Electronic supplementary materialThe online version of this article (doi:10.1186/s12284-014-0009-2) contains supplementary material, which is available to authorized users.
Highlights
Aspartic protease (APs) plays important roles in plant growth, development and biotic and abiotic stresses
Shimono et al (2003) found that OsAP77 induced by 10 fold with the microarray analysis after PBZ treatment (S02370) it was under the detection level by northern blot analysis
Characterization of putative cis-acting elements in the 5′-flanking region of OsAP77 In order to better understand the organization of the regulatory region of the OsAP77 gene, 1,999 bp fragment of the 5′-flanking region of OsAP77 was isolated by the combinations of primers; OsAP77 pro-5′ and OsAP77 pro-3′, respectively (Table 1)
Summary
Aspartic protease (APs) plays important roles in plant growth, development and biotic and abiotic stresses. We previously reported that the expression of a rice AP gene (OsAP77, Os10g0537800) was induced by probenazole (PBZ), a chemical inducer of disease resistance. Aspartic protease 77 (OsAP77, Os10g0537800, accession number AK061277) is a PBZ-inducible gene. More recently the overexpression of the rice ortholog (OsCDR1/OsAP5, Os01g08330) has been reported to induce resistance against fungal and bacterial infections in Arabidopsis and rice (Prasad et al 2009). Chen et al (2009) identified the total number of 96 AP genes in rice and showed the expression data for most of them Those of both OsCDR1/OsAP5 and OsAP77 were not shown in their list because it includes only OsAPs of which the expression was detectable in their test. Both APs have signal peptide and a protease motif but are different in active sites: presence/absence in OsCDR1/OsAP77, respectively (Chen et al 2009)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
