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Stress tolerance and grain yield of transgenic rice plants
Special Abstracts / Journal of Biotechnology 150S (2010) S1–S576
an extensive framework for new applied biotech tools. Although crop innovation and crop protection are based on general applied biotech principles, they must be adapted locally and be linked to the problems, priorities and local constraints of researchers and farmers.Rice and its pathogen Xanthomonas oryzae pv. oryzae (Xoo) provide an excellent example to assess the status and potential of biotech tools and their delivery into useful products in the field. During the last decade, the culture of rice has drastically increased in West-Africa, and Xoo, the causal agent of rice bacterial blight, has concomitantly increased in most West-African rice growing areas based on recent reports. Yield losses caused by Xoo range from 20 to 30% and can be as high as 50% in some areas. The disease is expanding to new rice-cultivated areas and represents a significant threat to food security in the region. The use of resistant cultivars is still the most economical and effective way to control this disease. To facilitate development of and strategic deployment of rice cultivars with resistance to bacterial blight, biotechnology tools and approaches, including marker-assisted breeding, gene combinations for disease control, and multiplex-PCR for pathogen diagnosis, have been developed. Although these technologies are routinely used in Asia and the USA, their application in West-Africa remains limited. Major challenges to their implementation in Africa are often the costs and the sophistication of the techniques required. Thus, developers of the technologies at research institutions need to work with end users from an early stage to create and promote the integration of successful, low cost applications of research biotech products. In this presentation we will give examples of the different biotechnologies available in our laboratories and others, or currently being developed to improve disease control. We will also discuss how to facilitate their application and delivery to the field. Improving the transfer of biotechnologies through existing laboratory hubs in Africa should greatly benefit African farmers by improving their ability to combat this economically important plant disease. doi:10.1016/j.jbiotec.2010.08.296 [P&F.19] Quorum sensing effects on Pseudomonas corrugata plant interaction and antagonistic activity Grazia Licciardello 1,2,∗ , Iris Bertani 3 , Laura Steindler 3 , Patrizia Bella 2 , Vittorio Venturi 3 , Vittoria Catara 2 1
Scientific and Technology Park of Sicily, Italy Department of Phytosanitary Science and Technologies, Italy 3 Bacteriology Group, International Centre for Genetic Engineering and Biotechnology, Italy Keywords: Quorum sensing; Pseudomonas corrugata; Tomato pith necrosis; Regulation 2
Quorum sensing (QS) is a cell-density dependent regulatory system, which in Pseudomonas spp. controls the expression of genes involved in virulence, biocontrol and ecological fitness. We investigated the role of QS in the phytopathogenic bacterium P. corrugata, causal agent of tomato pith necrosis. The genetic system PcoI-PcoR codifies for the LuxR transcriptional activator PcoR and the PcoI autoinducer synthase (LuxI family) responsible of the synthesis of N-acyl-homoserine lactones (AHLs) molecular signals. Analysis of knock-out mutants showed that QS is involved in virulence on tomato and in vitro antagonistic activity against a number of fungi and bacteria. In particular, QS seems to be involved in the regulation of lipodepsipeptide (LDP) production, a key virulence factor in tomato necrosis. We found that LDP production is cell-densitydependent.
S115
Further sequencing revealed that pcoI gene is co-transcribed with rfiA and is directly linked to QS. The deduced RfiA codifies for a transcriptional regulator belonging to the LuxR family protein that, differently to PcoR, does not contain an autoinducer binding domain. We also identified downstream rfiA, an operon, designated pcoABC, encoding for a tripartite resistance nodulationcell-division (RND) transporter system, partially involved in the secretion of LDP. Transcriptional analysis revealed that the expression of pcoABC is controlled by RfiA and QS by a hierarchical regulatory system. Knock-out mutants analysis showed that RfiA has a crucial role in P. corrugata/plant interaction. In fact, RfiA inactivation drastically reduced necrosis development in tomato pith and inhibited antagonistic activity related to LDP production in vitro. Tomato inoculation with different mutants revealed that in presence of AHLs, PcoR activates gene expression of virulence factors via RfiA. However, PcoR, in absence of AHL signals, can induce virulence gene expression via another yet unknown mechanism. doi:10.1016/j.jbiotec.2010.08.297 [P&F.20] Stress tolerance and grain yield of transgenic rice plants J.S. Jeong 1 , Y.S. Kim Kim 1 , Y.D. Choi 2 , M.K. Kim 2 , J.K. Kim 1,∗ 1
Myongji University, Korea, Republic of Seoul National University, Korea, Republic of Keywords: Drought tolerance; Transgenic rice; OsNAC10; Field test 2
Drought poses a serious threat to the sustainability of rice yields in rainfed agriculture. Here we report the results of a functional genomics approach that identified a rice NAC-domain gene, OsNAC10, which improved performance of transgenic rice plants under field drought conditions. A group of OsNAC genes were prescreened for enhanced stress tolerance when overexpressed in rice. The OsNAC10, one of the effective members selected from prescreening, is expressed predominantly in roots and panicles, and induced by drought, high salinity and abscisic acid. Overexpression of OsNAC10 in rice under the control of the constitutive promoter GOS2 and the root-specific promoter RCc3 increased the plant tolerance to drought, high salinity and low temperature at the vegetative stage. More importantly, the RCc3:OsNAC10 plants showed significantly enhanced drought tolerance at the reproductive stage, increasing grain yield by 25-42% and 5-14% over controls in the field under drought and normal conditions, respectively. Grain yield of GOS2:OsNAC10 plants in the field, in contrast, remained similar to that of controls under both normal and drought conditions. These differences in performance under field drought conditions reflect the difference in expression of OsNAC10-dependent target genes in roots as well as in leaves of the two transgenic plants, as revealed by microarray analyses. Root diameter of the RCc3:OsNAC10 plants was thicker by 1.25-fold than that of the GOS2:OsNAC10 and NT plants due to the enlarged stele, cortex and epidermis. Overall, our results demonstrated that root specific overexpression of OsNAC10 enlarges roots, enhancing drought tolerance of transgenic plants, which increases grain yield significantly under field drought conditions. doi:10.1016/j.jbiotec.2010.08.298
an extensive framework for new applied biotech tools. Although crop innovation and crop protection are based on general applied biotech principles, they must be adapted locally and be linked to the problems, priorities and local constraints of researchers and farmers.Rice and its pathogen Xanthomonas oryzae pv. oryzae (Xoo) provide an excellent example to assess the status and potential of biotech tools and their delivery into useful products in the field. During the last decade, the culture of rice has drastically increased in West-Africa, and Xoo, the causal agent of rice bacterial blight, has concomitantly increased in most West-African rice growing areas based on recent reports. Yield losses caused by Xoo range from 20 to 30% and can be as high as 50% in some areas. The disease is expanding to new rice-cultivated areas and represents a significant threat to food security in the region. The use of resistant cultivars is still the most economical and effective way to control this disease. To facilitate development of and strategic deployment of rice cultivars with resistance to bacterial blight, biotechnology tools and approaches, including marker-assisted breeding, gene combinations for disease control, and multiplex-PCR for pathogen diagnosis, have been developed. Although these technologies are routinely used in Asia and the USA, their application in West-Africa remains limited. Major challenges to their implementation in Africa are often the costs and the sophistication of the techniques required. Thus, developers of the technologies at research institutions need to work with end users from an early stage to create and promote the integration of successful, low cost applications of research biotech products. In this presentation we will give examples of the different biotechnologies available in our laboratories and others, or currently being developed to improve disease control. We will also discuss how to facilitate their application and delivery to the field. Improving the transfer of biotechnologies through existing laboratory hubs in Africa should greatly benefit African farmers by improving their ability to combat this economically important plant disease. doi:10.1016/j.jbiotec.2010.08.296 [P&F.19] Quorum sensing effects on Pseudomonas corrugata plant interaction and antagonistic activity Grazia Licciardello 1,2,∗ , Iris Bertani 3 , Laura Steindler 3 , Patrizia Bella 2 , Vittorio Venturi 3 , Vittoria Catara 2 1
Scientific and Technology Park of Sicily, Italy Department of Phytosanitary Science and Technologies, Italy 3 Bacteriology Group, International Centre for Genetic Engineering and Biotechnology, Italy Keywords: Quorum sensing; Pseudomonas corrugata; Tomato pith necrosis; Regulation 2
Quorum sensing (QS) is a cell-density dependent regulatory system, which in Pseudomonas spp. controls the expression of genes involved in virulence, biocontrol and ecological fitness. We investigated the role of QS in the phytopathogenic bacterium P. corrugata, causal agent of tomato pith necrosis. The genetic system PcoI-PcoR codifies for the LuxR transcriptional activator PcoR and the PcoI autoinducer synthase (LuxI family) responsible of the synthesis of N-acyl-homoserine lactones (AHLs) molecular signals. Analysis of knock-out mutants showed that QS is involved in virulence on tomato and in vitro antagonistic activity against a number of fungi and bacteria. In particular, QS seems to be involved in the regulation of lipodepsipeptide (LDP) production, a key virulence factor in tomato necrosis. We found that LDP production is cell-densitydependent.
S115
Further sequencing revealed that pcoI gene is co-transcribed with rfiA and is directly linked to QS. The deduced RfiA codifies for a transcriptional regulator belonging to the LuxR family protein that, differently to PcoR, does not contain an autoinducer binding domain. We also identified downstream rfiA, an operon, designated pcoABC, encoding for a tripartite resistance nodulationcell-division (RND) transporter system, partially involved in the secretion of LDP. Transcriptional analysis revealed that the expression of pcoABC is controlled by RfiA and QS by a hierarchical regulatory system. Knock-out mutants analysis showed that RfiA has a crucial role in P. corrugata/plant interaction. In fact, RfiA inactivation drastically reduced necrosis development in tomato pith and inhibited antagonistic activity related to LDP production in vitro. Tomato inoculation with different mutants revealed that in presence of AHLs, PcoR activates gene expression of virulence factors via RfiA. However, PcoR, in absence of AHL signals, can induce virulence gene expression via another yet unknown mechanism. doi:10.1016/j.jbiotec.2010.08.297 [P&F.20] Stress tolerance and grain yield of transgenic rice plants J.S. Jeong 1 , Y.S. Kim Kim 1 , Y.D. Choi 2 , M.K. Kim 2 , J.K. Kim 1,∗ 1
Myongji University, Korea, Republic of Seoul National University, Korea, Republic of Keywords: Drought tolerance; Transgenic rice; OsNAC10; Field test 2
Drought poses a serious threat to the sustainability of rice yields in rainfed agriculture. Here we report the results of a functional genomics approach that identified a rice NAC-domain gene, OsNAC10, which improved performance of transgenic rice plants under field drought conditions. A group of OsNAC genes were prescreened for enhanced stress tolerance when overexpressed in rice. The OsNAC10, one of the effective members selected from prescreening, is expressed predominantly in roots and panicles, and induced by drought, high salinity and abscisic acid. Overexpression of OsNAC10 in rice under the control of the constitutive promoter GOS2 and the root-specific promoter RCc3 increased the plant tolerance to drought, high salinity and low temperature at the vegetative stage. More importantly, the RCc3:OsNAC10 plants showed significantly enhanced drought tolerance at the reproductive stage, increasing grain yield by 25-42% and 5-14% over controls in the field under drought and normal conditions, respectively. Grain yield of GOS2:OsNAC10 plants in the field, in contrast, remained similar to that of controls under both normal and drought conditions. These differences in performance under field drought conditions reflect the difference in expression of OsNAC10-dependent target genes in roots as well as in leaves of the two transgenic plants, as revealed by microarray analyses. Root diameter of the RCc3:OsNAC10 plants was thicker by 1.25-fold than that of the GOS2:OsNAC10 and NT plants due to the enlarged stele, cortex and epidermis. Overall, our results demonstrated that root specific overexpression of OsNAC10 enlarges roots, enhancing drought tolerance of transgenic plants, which increases grain yield significantly under field drought conditions. doi:10.1016/j.jbiotec.2010.08.298