ស្វែងរកតាមប្រភេទឯកសារ
ស្វែងរកតាមប្រភេទដំណាំ
អត្ថបទថ្មីៗ
ចំនួនភ្ញៀវចូលទស្សនា
        
ថ្ងៃនេះ
ថ្ងៃម្សិលមិញ
សប្តាហ៍នេះ
សប្តាហ័មុន
ខែនេះ
ខែមុន
ពាក្យគន្លឺះ  

ស្វែងរក
ស្វែងរកលំអិត
បណ្ណាល័យ
ចំណងជើង:
Increased productivity of rainfed lowland rice cropping systems of the Mekong region, by Shu Fukai, Makara Ouk, Crop & Pasture Science, 2012, 63, 944–973
បរិយាយ:
Abstract

Rice in Thailand, Laos and Cambodia (the Mekong region) is grown mostly as a mono crop once a year in the wet season in the rainfed lowlands. Some lowland areas have access to irrigation water, and rice double cropping is practised while non-rice crops are grown in a limited area in the dry season after harvesting wet season rice. In all cases wet season rice is grown mostly for subsistence under rainfed with low input, and combined with low soil fertility and frequent occurrence of drought, the yield is generally low with a mean of 2.5 t/ha and the yield increase was slow in recent years. More recently demand for labour in the regional centres has caused labour shortages in the rural area and rice crops may not be managed in the traditional manner such as the practice of manually transplanting of rice seedlings. For the last two decades research efforts have been made to minimise the adverse effect of abiotic factors and to meet the changing nature of the socioeconomic environment, resulting in increased understanding of factors determining productivity of rainfed lowland rice and the cropping systems based on it. This review describes such achievements in five sections – water environment characterisation to quantify drought problems, soil environment and fertiliser management, direct seeding to develop technology to cope with the labour shortage, variety improvement for rainfed lowland rice in drought-prone environment, and crop intensification and diversification that shift practices from traditional subsistence agriculture to more market-oriented agriculture. Each section is concluded with issues for future research need. The last section of the paper describes future research challenges for the rainfed rice-based lowland cropping systems in the Mekong region and possible implication on rainfed lowland rice system on other regions.

Full article
 
keyword:
cropping system, direct seeding, drought, rainfed lowland rice, rice breeding, soil fertility.
Abstract

Rice in Thailand, Laos and Cambodia (the Mekong region) is grown mostly as a mono crop once a year in the wet season in the rainfed lowlands. Some lowland areas have access to irrigation water, and rice double cropping is practised while non-rice crops are grown in a limited area in the dry season after harvesting wet season rice. In all cases wet season rice is grown mostly for subsistence under rainfed with low input, and combined with low soil fertility and frequent occurrence of drought, the yield is generally low with a mean of 2.5 t/ha and the yield increase was slow in recent years. More recently demand for labour in the regional centres has caused labour shortages in the rural area and rice crops may not be managed in the traditional manner such as the practice of manually transplanting of rice seedlings. For the last two decades research efforts have been made to minimise the adverse effect of abiotic factors and to meet the changing nature of the socioeconomic environment, resulting in increased understanding of factors determining productivity of rainfed lowland rice and the cropping systems based on it. This review describes such achievements in five sections – water environment characterisation to quantify drought problems, soil environment and fertiliser management, direct seeding to develop technology to cope with the labour shortage, variety improvement for rainfed lowland rice in drought-prone environment, and crop intensification and diversification that shift practices from traditional subsistence agriculture to more market-oriented agriculture. Each section is concluded with issues for future research need. The last section of the paper describes future research challenges for the rainfed rice-based lowland cropping systems in the Mekong region and possible implication on rainfed lowland rice system on other regions.

Full article
 
ចំណងជើង:
Farmers’ perceptions on cassava cultivation in Cambodia, by U. Sopheap, A. Patanothaiand T.M. Aye, KHON KAEN AGR. J. 39 : 279-294 (2011).
បរិយាយ:
Abstract
Cassava is one of the most important upland crops of Cambodia. While improved technologies are needed for sustainable production of the crop, their adoption depends on how farmers view cassava against other crops. The objective of this study was to assess the perception of Cambodian farmers on growing cassava, relative to other upland crops. The study was conducted in Kampong Cham province in Northeast Cambodia which has the largest cassava production area in the country. Secondary data on production and price of cassava and other crops were collected, and 45 households in four cassava production zones were interviewed to obtain information on farmer's perceptions on cassava and other crops. The results showed that production of cassava and other upland crops in Cambodia has increased substantially during recent years, reflecting increased market demand and improved prices. Farmers in the study area in Kampong Cham province regard rice and cassava as their priority crops, and have a greater preference for growing them than other crops, including maize, soybean, mungbean, peanut, sesame and rubber. Rice, however, is grown mainly for domestic consumption, while cassava is grown as a source of cash income. The marketing aspects of the crop, i.e., good price and easy to sell, were the most important considerations for farmers' strong preference for cassava relative to other upland crops. With the current trend of favorable marketing conditions, cassava production in Cambodia is anticipated to expand further, while farmers are also likely to adopt improved technologies that will sustain or improve their cassava yields, even if involving extra input costs. These findings can potentially be used as a basis for the further development and extension of technologies for sustainable production of cassava in Cambodia.

Full article


keyword:
Cassava production, upland crops, farmers’ preference, farmers’ attitude, technology adoption.
Abstract
Cassava is one of the most important upland crops of Cambodia. While improved technologies are needed for sustainable production of the crop, their adoption depends on how farmers view cassava against other crops. The objective of this study was to assess the perception of Cambodian farmers on growing cassava, relative to other upland crops. The study was conducted in Kampong Cham province in Northeast Cambodia which has the largest cassava production area in the country. Secondary data on production and price of cassava and other crops were collected, and 45 households in four cassava production zones were interviewed to obtain information on farmer's perceptions on cassava and other crops. The results showed that production of cassava and other upland crops in Cambodia has increased substantially during recent years, reflecting increased market demand and improved prices. Farmers in the study area in Kampong Cham province regard rice and cassava as their priority crops, and have a greater preference for growing them than other crops, including maize, soybean, mungbean, peanut, sesame and rubber. Rice, however, is grown mainly for domestic consumption, while cassava is grown as a source of cash income. The marketing aspects of the crop, i.e., good price and easy to sell, were the most important considerations for farmers' strong preference for cassava relative to other upland crops. With the current trend of favorable marketing conditions, cassava production in Cambodia is anticipated to expand further, while farmers are also likely to adopt improved technologies that will sustain or improve their cassava yields, even if involving extra input costs. These findings can potentially be used as a basis for the further development and extension of technologies for sustainable production of cassava in Cambodia.

Full article


ចំណងជើង:
Unveiling constraints to cassava production in Cambodia: An analysis from farmers’ yield variations, by U. Sopheap; A. Patanothai; T.M. Aye, Article 2, Volume 6, Issue 4, Autumn 2012, Page 409-428
បរិយាយ:
Abstract
Cassava (Manihot esculenta Crantz) is currently the most important upland crop of Cambodia, but information on yield variations and causal factors which is important for efficiently targeting efforts to increase production is still lacking. The objectives of this study were to determine the yield variations and causal factors for cassava production in Kampong Cham province in Cambodia. Forty five households in four production zones were selected for the study. A farm survey employing semi-structured interviews, combined with field visits, were used for the collection of information on farmers' practices in cassava cultivation, while crop cutting was done to provide estimates of cassava yields. The data were analyzed for yield variations, yield gaps and causal factors. The results showed large variations in yield among farmers' fields, ranging from 12.7 to 37.2 t ha -1. The fields were divided into five yield categories, with the mean yields of the lower four categories ranging from 76.0 to 34.2% of the maximum yields, with corresponding yield gaps ranging from 8.9 to 24.4 t ha -1. The main yield constraints identified were soil nutrient deficits, short crop duration and weed competition. The highest yielding fields had no production constraints, but the number and/or the level of constraints increased in fields with lower crop yields. However, for different fields with similar yield levels, the main production constraints sometimes differed. The results clearly indicated that there are opportunities for yield improvement and narrowing of yield gaps through the adoption of field specific improved technologies and management practices.

Full Article


keyword:
Keywords: Yield gap; Yield limiting factors; Cassava cultivation; Production constraints; crop management
Abstract
Cassava (Manihot esculenta Crantz) is currently the most important upland crop of Cambodia, but information on yield variations and causal factors which is important for efficiently targeting efforts to increase production is still lacking. The objectives of this study were to determine the yield variations and causal factors for cassava production in Kampong Cham province in Cambodia. Forty five households in four production zones were selected for the study. A farm survey employing semi-structured interviews, combined with field visits, were used for the collection of information on farmers' practices in cassava cultivation, while crop cutting was done to provide estimates of cassava yields. The data were analyzed for yield variations, yield gaps and causal factors. The results showed large variations in yield among farmers' fields, ranging from 12.7 to 37.2 t ha -1. The fields were divided into five yield categories, with the mean yields of the lower four categories ranging from 76.0 to 34.2% of the maximum yields, with corresponding yield gaps ranging from 8.9 to 24.4 t ha -1. The main yield constraints identified were soil nutrient deficits, short crop duration and weed competition. The highest yielding fields had no production constraints, but the number and/or the level of constraints increased in fields with lower crop yields. However, for different fields with similar yield levels, the main production constraints sometimes differed. The results clearly indicated that there are opportunities for yield improvement and narrowing of yield gaps through the adoption of field specific improved technologies and management practices.

Full Article


ចំណងជើង:
Pathogenicity of Rice Blast (Pyricularia oryzae Cavara) Isolates from Cambodia, by Yoshimichi FUKUTA, Ikumi KOGA, Tochi UNG, Khay SATHYA, Akiko KAWASAKI-TANAKA, Yohei KOIDE, Nobuya KOBAYASHI, Mitsuhiro OBARA, Hun YADANA, Nagao HAYASHI,
បរិយាយ:
Abstract
The evaluation of a total of 122 blast (Pyricularia oryzae Cavara) isolates collected from the Tonle Sap and Mekong river regions of Cambodia revealed wide variation. Using a new designation system, the blast isolates were categorized into 92 races based on the reaction patterns of rice (Oryza sativa L.) differential varieties (DVs) harboring 23 resistance genes and of 1 susceptible cultivar, Lijiangxintuanheigu (LTH). Cluster analysis was used to classify the blast isolates into 3 groups — I, IIa, and IIb — using data from these reaction patterns of the DVs and LTH. We used the classifications established under the new designation system, alongside cluster analysis and the geographical distribution of blast isolates, to investigate the diversity and differentiation of blast races in the Tonle Sap and Mekong river regions. The distributions of the blast races differed between the 2 regions, although blast isolates of group IIa were distributed commonly in both regions and groups I and IIb occurred at higher frequencies in the Tonle Sap region rather than the Mekong region. The blast isolates in groups I and IIb were also less diverse than those in group IIa. Accordingly, Group II blast isolates overall were distributed in both regions with high diversity, but some modified blast isolates were additionally distributed in the Tonle Sap region. We also investigated the pathogenicities of blast isolates from wild rice (Oryza rufipogon Griff) weeds neighboring the cultivated rice, and discuss the relationship between these isolates and those from cultivated rice.

Full Article
keyword:
cluster analysis, differential variety, diversity, pathotype, resistance gene
Abstract
The evaluation of a total of 122 blast (Pyricularia oryzae Cavara) isolates collected from the Tonle Sap and Mekong river regions of Cambodia revealed wide variation. Using a new designation system, the blast isolates were categorized into 92 races based on the reaction patterns of rice (Oryza sativa L.) differential varieties (DVs) harboring 23 resistance genes and of 1 susceptible cultivar, Lijiangxintuanheigu (LTH). Cluster analysis was used to classify the blast isolates into 3 groups — I, IIa, and IIb — using data from these reaction patterns of the DVs and LTH. We used the classifications established under the new designation system, alongside cluster analysis and the geographical distribution of blast isolates, to investigate the diversity and differentiation of blast races in the Tonle Sap and Mekong river regions. The distributions of the blast races differed between the 2 regions, although blast isolates of group IIa were distributed commonly in both regions and groups I and IIb occurred at higher frequencies in the Tonle Sap region rather than the Mekong region. The blast isolates in groups I and IIb were also less diverse than those in group IIa. Accordingly, Group II blast isolates overall were distributed in both regions with high diversity, but some modified blast isolates were additionally distributed in the Tonle Sap region. We also investigated the pathogenicities of blast isolates from wild rice (Oryza rufipogon Griff) weeds neighboring the cultivated rice, and discuss the relationship between these isolates and those from cultivated rice.

Full Article
ចំណងជើង:
Analysis of major constraints and opportunities of chilli and tomato for off-season production and their marketing in Kampot Province, Cambodia, by SINATH SREY, MASTER OF AGRIBUSINESS, 2013
បរិយាយ:

keyword:
N/A

ចំណងជើង:
Resilience of Cambodian lowland rice farming systems to future climate uncertainty, by P.L. Poulton, N.P. Dalgliesh, S. Vang, C.H. Roth, Field Crops Research 198 (2016) 160–170
បរិយាយ:
Abstract

Rice production is the major source of food security in Cambodia where 85% of the total arable land is cultivated to rice with traditional transplanted medium and later maturity varieties accounting for >70% of the plantings during the monsoon period. Climate change poses risks and opportunities to the sus- tained productivity of rice based farming systems in Cambodia. The objective of this study is to evaluate adaptation strategies that support the replacement of traditional low input systems with a ‘response’ farming approach for better temporal utilisation of available labour, land and water resources. Options include replacing a traditional transplanted crop with short duration varieties, more efficient crop estab- lishment methods and better agronomic and fertiliser management that responds to timing, intensity and longevity of the monsoon and has potential to mitigate effects of current and future climate variabil- ity. To achieve this, we apply the APSIM farming systems model to evaluate how adaptation options for smallholder farmers can increase or maintain overall productivity within present day climate variability and future climates, using downscaled GCM baseline and 2030 climate scenarios. To extend beyond the 2030 climate change scenarios, we also assess production risk from an increase in ambient air temper- ature of 1.4–4.3 ◦C, atmospheric CO2 concentration of 545–885 ppm and variation in rainfall, for rainfed and irrigated systems to 2090. Modelled scenarios indicate a yield response to elevated CO2 of 17.5% at a concentration of 680 ppm for current temperature and rainfall and are consistent with established physiological effects of CO2 on crop yields. In response to temperature, yields decreased by 4% per degree increase from an average annual baseline temperature of 28 ◦C. Adaptation strategies involving deploy- ment of short duration rice varieties, in conjunction with direct seeding and better N management, indicate comparable and improved production can be achieved to 2030 under likely future climate pro- jections. However, beyond 2030, the distribution and timing of rainfall has a significant influence on rainfed lowland rice in Cambodia. In this case a more transformational approach involving widespread provision of irrigation water will be required to offset climate change impacts.

Full Article
 
keyword:
APSIM Climate change Response farming Cambodia Rice
Abstract

Rice production is the major source of food security in Cambodia where 85% of the total arable land is cultivated to rice with traditional transplanted medium and later maturity varieties accounting for >70% of the plantings during the monsoon period. Climate change poses risks and opportunities to the sus- tained productivity of rice based farming systems in Cambodia. The objective of this study is to evaluate adaptation strategies that support the replacement of traditional low input systems with a ‘response’ farming approach for better temporal utilisation of available labour, land and water resources. Options include replacing a traditional transplanted crop with short duration varieties, more efficient crop estab- lishment methods and better agronomic and fertiliser management that responds to timing, intensity and longevity of the monsoon and has potential to mitigate effects of current and future climate variabil- ity. To achieve this, we apply the APSIM farming systems model to evaluate how adaptation options for smallholder farmers can increase or maintain overall productivity within present day climate variability and future climates, using downscaled GCM baseline and 2030 climate scenarios. To extend beyond the 2030 climate change scenarios, we also assess production risk from an increase in ambient air temper- ature of 1.4–4.3 ◦C, atmospheric CO2 concentration of 545–885 ppm and variation in rainfall, for rainfed and irrigated systems to 2090. Modelled scenarios indicate a yield response to elevated CO2 of 17.5% at a concentration of 680 ppm for current temperature and rainfall and are consistent with established physiological effects of CO2 on crop yields. In response to temperature, yields decreased by 4% per degree increase from an average annual baseline temperature of 28 ◦C. Adaptation strategies involving deploy- ment of short duration rice varieties, in conjunction with direct seeding and better N management, indicate comparable and improved production can be achieved to 2030 under likely future climate pro- jections. However, beyond 2030, the distribution and timing of rainfall has a significant influence on rainfed lowland rice in Cambodia. In this case a more transformational approach involving widespread provision of irrigation water will be required to offset climate change impacts.

Full Article
 
ចំណងជើង:
Resistance to Sri Lankan Cassava MosaicVirus (SLCMV) in Genetically Engineered Cassava cv. KU50 through RNA Silencing, by Valentine Otang Ntui, Kynet Kong, Raham Sher Khan, Tomoko Igawa, Gnanaguru Janaky Janavi , Ramalingam Rabindran, Ikuo Nakamura , Masahiro Mii, PLOS ONE | DOI:10.1371/journal.pone.0120551 April 22, 2015
បរិយាយ:
Abstract
Cassava ranks fifth among the starch producing crops of the world, its annual bioethanol yield is higher than for any other crop. Cassava cultivar KU50, the most widely grown culti- var for non-food purposes is susceptible to Sri Lankan cassava mosaic virus (SLCMV). The objective of this work was to engineer resistance to SLCMV by RNA interference (RNAi) in order to increase biomass yield, an important aspect for bioethanol production. Here, we produced transgenic KU50 lines expressing dsRNA homologous to the region between the AV2 and AV1 of DNA A of SLCMV. High level expression of dsRNA of SLCMV did not in- duce any growth abnormality in the transgenic plants. Transgenic lines displayed high lev- els of resistance to SLCMV compared to the wild-type plants and no virus load could be detected in uninoculated new leaves of the infected resistant lines after PCR amplification and RT-PCR analysis. The agronomic performance of the transgenic lines was unimpaired after inoculation with the virus as the plants presented similar growth when compared to the mock inoculated control plants and revealed no apparent reduction in the amount and weight of tubers produced. We show that the resistance is correlated with post-transcription- al gene silencing because of the production of transgene specific siRNA. The results dem- onstrate that transgenic lines exhibited high levels of resistance to SLCMV. This resistance coupled with the desirable yield components in the transgenic lines makes them better can- didates for exploitation in the production of biomass as well as bioethanol.

Full Article
 
keyword:
N/A
Abstract
Cassava ranks fifth among the starch producing crops of the world, its annual bioethanol yield is higher than for any other crop. Cassava cultivar KU50, the most widely grown culti- var for non-food purposes is susceptible to Sri Lankan cassava mosaic virus (SLCMV). The objective of this work was to engineer resistance to SLCMV by RNA interference (RNAi) in order to increase biomass yield, an important aspect for bioethanol production. Here, we produced transgenic KU50 lines expressing dsRNA homologous to the region between the AV2 and AV1 of DNA A of SLCMV. High level expression of dsRNA of SLCMV did not in- duce any growth abnormality in the transgenic plants. Transgenic lines displayed high lev- els of resistance to SLCMV compared to the wild-type plants and no virus load could be detected in uninoculated new leaves of the infected resistant lines after PCR amplification and RT-PCR analysis. The agronomic performance of the transgenic lines was unimpaired after inoculation with the virus as the plants presented similar growth when compared to the mock inoculated control plants and revealed no apparent reduction in the amount and weight of tubers produced. We show that the resistance is correlated with post-transcription- al gene silencing because of the production of transgene specific siRNA. The results dem- onstrate that transgenic lines exhibited high levels of resistance to SLCMV. This resistance coupled with the desirable yield components in the transgenic lines makes them better can- didates for exploitation in the production of biomass as well as bioethanol.

Full Article
 
ចំណងជើង:
Retransformation of Marker-Free Potato for Enhanced Resistance Against Fungal Pathogens by Pyramiding Chitinase and Wasabi Defensin Genes, by Raham Sher Khan, Nader Ahmed Darwish, Bushra Khattak, Valentine Otang Ntui, Kynet Kong, Kazuki Shimomae, Ikuo Nakamura, Masahiro Mii, Mol Biotechnol DOI 10.1007/s12033-014-9760-2
បរិយាយ:

Abstract

Multi-auto-transformation vector system has been one of the strategies to produce marker-free transgenic plants without using selective chemicals and plant growth regulators and thus facilitating transgene stacking. In the study reported here, retransformation was carried out in marker-free transgenic potato CV. May Queen containing ChiC gene (isolated from Streptomyces griseus strain HUT 6037) with wasabi defensin (WD) gene (isolated from Wasabia japonica) to pyramid the two disease resistant genes. Molecular analyses of the developed shoots confirmed the existence of both the genes of interest (ChiC and WD) in transgenic plants. Co-expression of the genes was confirmed by RT-PCR, northern blot, and western blot analyses. Disease resistance assay of in vitro plants showed that the transgenic lines co-expressing both the ChiC and WD genes had higher resistance against the fungal pathogens, Fusarium oxysporum (Fusarium wilt) and Alternaria solani (early blight) compared to the non-transformed control and the transgenic lines expressing either of the ChiC or WD genes. The disease resistance potential of the transgenic plants could be increased by transgene stacking or multiple transformations.

Full Article
 

keyword:
Retransformation, MAT vector, Genestacking, Fusarium oxysporum, Alternaria solani, Potato

Abstract

Multi-auto-transformation vector system has been one of the strategies to produce marker-free transgenic plants without using selective chemicals and plant growth regulators and thus facilitating transgene stacking. In the study reported here, retransformation was carried out in marker-free transgenic potato CV. May Queen containing ChiC gene (isolated from Streptomyces griseus strain HUT 6037) with wasabi defensin (WD) gene (isolated from Wasabia japonica) to pyramid the two disease resistant genes. Molecular analyses of the developed shoots confirmed the existence of both the genes of interest (ChiC and WD) in transgenic plants. Co-expression of the genes was confirmed by RT-PCR, northern blot, and western blot analyses. Disease resistance assay of in vitro plants showed that the transgenic lines co-expressing both the ChiC and WD genes had higher resistance against the fungal pathogens, Fusarium oxysporum (Fusarium wilt) and Alternaria solani (early blight) compared to the non-transformed control and the transgenic lines expressing either of the ChiC or WD genes. The disease resistance potential of the transgenic plants could be increased by transgene stacking or multiple transformations.

Full Article
 

ចំណងជើង:
RNAi-Mediated Resistance to Cucumber Mosaic Virus (CMV) in Genetically Engineered Tomato, by Valentine Otang Ntui, Kynet Kong, Pejman Azadi, Raham Sher Khan, Dong Poh Chin, Tomoko Igawa, Masahiro Mii, Ikuo Nakamura. American Journal of Plant Sciences, 2014, 5, 554-572
បរិយាយ:
Abstract
Cucumber  mosaic  virus  is  one  of  the  most  constraints  to  the  production  of  tomato and  other vegetable crops worldwide. Here, we generated an RNAi construct containing inverted repeat of  1138  bp  fragment  of  a  partial  replicase  gene  of  CMV-O  and  used  it  to  produce  transgenic tomato plants expressing CMV-specific dsRNA of the replicase gene. Inoculation of transgenic plants  with  CMV  strain  O  discriminated  three  categories  of  plants: plants  that  showed  com- plete resistance, which were free of symptoms; highly resistant plants, which had mild symp- toms,  but  later  recovered  because  new  leaves  that  emerged  were  free  of  symptoms;  and  sus- ceptible  plants,  which  showed  severe  symptoms  similar  to  wild-type  plants.  The  completely resistant lines were selected and challenged with a closely related strain, CMV-Y. Interestingly, the transgenic plant lines either remained immune or showed high levels of resistance to the strain.  No virus  could  be  detected  in  uninoculated  new  leaves  of  the  resistant  lines  after RT-PCR  and  Dot  immunobinding  assay  (DIBA)  analyses.  We  could  show  that  the  resistance  is correlated with  post-transcriptional  gene  silencing  because  of  the  production  of  transgenic specific siRNA.

Full Article
 
keyword:
CMV; dsRNA; PTGS; Replicase Gene; RNAi; Tomato
Abstract
Cucumber  mosaic  virus  is  one  of  the  most  constraints  to  the  production  of  tomato and  other vegetable crops worldwide. Here, we generated an RNAi construct containing inverted repeat of  1138  bp  fragment  of  a  partial  replicase  gene  of  CMV-O  and  used  it  to  produce  transgenic tomato plants expressing CMV-specific dsRNA of the replicase gene. Inoculation of transgenic plants  with  CMV  strain  O  discriminated  three  categories  of  plants: plants  that  showed  com- plete resistance, which were free of symptoms; highly resistant plants, which had mild symp- toms,  but  later  recovered  because  new  leaves  that  emerged  were  free  of  symptoms;  and  sus- ceptible  plants,  which  showed  severe  symptoms  similar  to  wild-type  plants.  The  completely resistant lines were selected and challenged with a closely related strain, CMV-Y. Interestingly, the transgenic plant lines either remained immune or showed high levels of resistance to the strain.  No virus  could  be  detected  in  uninoculated  new  leaves  of  the  resistant  lines  after RT-PCR  and  Dot  immunobinding  assay  (DIBA)  analyses.  We  could  show  that  the  resistance  is correlated with  post-transcriptional  gene  silencing  because  of  the  production  of  transgenic specific siRNA.

Full Article
 
ចំណងជើង:
Synthetic chitinase gene driven by root-specific LjNRT2 and AtNRT2.1 promoters confers resistance to Fusarium oxysporum in transgenic tobacco and tomato, by Kynet Kong, So Makabe, Valentine Otang Ntui, Raham Sher Khan, Ikuo Nakamura. Plant Biotechnol Rep DOI 10.1007/s11816-013-0303-2
បរិយាយ:

Abstract

Fusarium wilt is a soil-borne disease causing substantial yield losses in various crops and vegetables. We have previously reported the synthetic chitinase (NIC) gene (1.2 kb), in which codon usage of fungus, replaced with that of plant, conferred resistance against Botrytis cinerea. In this study, the NIC or GUS gene was linked to two root-specific promoters, LjNRT2 or AtNRT2.1 (nitrate transporter 2), derived from Lotus japonica and Arabidopsis thaliana, respectively. Transgenic tobacco lines expressing LjNRT2-GUS and LjNRT2-NIC, and tomato lines expressing AtNRT2.1-NIC, were produced by Agrobacterium-mediated transformation. GUS histochemical staining was observed in vascular regions of the roots but was conspicuously absent in the leaves of transgenic plants. Western blot analysis showed the production of NIC proteins in the roots but not in the leaves of transgenic tobacco and tomato lines. These results indicate that LjNRT2 and AtNRT2.1 promoters expressed transgenes in a root-specific manner. When in vitro whole plant resistance assay against Fusarium oxysporum was conducted, transgenic plants showed increased levels of resistance compared to non-transgenic plants. Antifungal activities of the root extract against spore germination of F. oxysporum showed lower CFU (colony-forming unit) than those of the leaf extract. Root colonization assay against F. oxysporum showed much lower CFU values in the roots of transgenic plants than in those of non-transgenic plants. These results suggest that NIC gene triggered by the root-specific promoters successfully expressed only in the roots and conferred increased levels of resistance against the root pathogen, F. oxysporum.

Full article

keyword:
Biosafety. Fusarium oxysporum. Root colonization. Root-specific promoter. Soil borne disease. Synthetic chitinase gene

Abstract

Fusarium wilt is a soil-borne disease causing substantial yield losses in various crops and vegetables. We have previously reported the synthetic chitinase (NIC) gene (1.2 kb), in which codon usage of fungus, replaced with that of plant, conferred resistance against Botrytis cinerea. In this study, the NIC or GUS gene was linked to two root-specific promoters, LjNRT2 or AtNRT2.1 (nitrate transporter 2), derived from Lotus japonica and Arabidopsis thaliana, respectively. Transgenic tobacco lines expressing LjNRT2-GUS and LjNRT2-NIC, and tomato lines expressing AtNRT2.1-NIC, were produced by Agrobacterium-mediated transformation. GUS histochemical staining was observed in vascular regions of the roots but was conspicuously absent in the leaves of transgenic plants. Western blot analysis showed the production of NIC proteins in the roots but not in the leaves of transgenic tobacco and tomato lines. These results indicate that LjNRT2 and AtNRT2.1 promoters expressed transgenes in a root-specific manner. When in vitro whole plant resistance assay against Fusarium oxysporum was conducted, transgenic plants showed increased levels of resistance compared to non-transgenic plants. Antifungal activities of the root extract against spore germination of F. oxysporum showed lower CFU (colony-forming unit) than those of the leaf extract. Root colonization assay against F. oxysporum showed much lower CFU values in the roots of transgenic plants than in those of non-transgenic plants. These results suggest that NIC gene triggered by the root-specific promoters successfully expressed only in the roots and conferred increased levels of resistance against the root pathogen, F. oxysporum.

Full article

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