Volatile organic compounds (VOC) play an important role in protecting plants from insect and path... more Volatile organic compounds (VOC) play an important role in protecting plants from insect and pathogen attack. In this study, we investigated the leaf volatile profiles of 14 citrus varieties. The VOC in citrus leaves were extracted with n-hexane and analyzed using gas chromatography-mass spectrometry (GC-MS). Overall, 4six volatile compounds were identified in the n-hexane extract from citrus leaves. Most of the detected compounds belonged to 3 main groups (monoterpenes, sesquiterpenes, and aliphatic aldehydes). Principle component analysis was used to examine the relative distribution of the studied varieties to each other. Interestingly, volatile profiles of varieties that are tolerant to Candidatus Liberibacter asiaticus (CLas) were different from those of the susceptible ones. Tolerant and moderately tolerant cultivars contained relatively higher amounts of volatiles than susceptible varieties. In addition, tolerant varieties were also higher in specific compounds which are known for their antimicrobial activities. These compounds include Aldehydes (undecanal, neral, geranial, and citronellal) and some monoterpenes such as linalool, d-limonene, myrcene, a- and b- phellandrene. In addition, some sesquiterpene compounds including t-caryophellene, g-elemene, b-elemene, germacrene D, and geranyl acetate were higher in tolerant and moderately tolerant cultivars. Severinia buxifolia which is known for its tolerance to CLas and many other pathogens contained higher levels of santalenes and coumarins. Our results indicated that citrus leaf volatiles might play a role in citrus tolerance to CLas. The results of this study may help in understanding of the mechanism of citrus tolerance against CLas.
Phytohormones mainly affect plant development and trigger varied responses to biotic and abiotic ... more Phytohormones mainly affect plant development and trigger varied responses to biotic and abiotic stresses. The sensitivity of methods used to profile phytohormones is a vital factor that affects the results. We used an improved GC–MS-based method in the selective ion-monitoring (SIM) mode to study the phytohormone profiling in citrus tissues. One extraction solvent mixture and two derivatization reagents were used, methyl chloroformate (MCF) and N-Methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA). The method showed a low limit of detection and low limit of quantification with high extraction recovery percentage and reproducibility. Overall, we detected 13 phytohormones belonging to six different groups. Auxins, SAs, tJA, and ABA were detected after derivatization with MCF while cytokinins and GAs were detected after derivatization with MSTFA. Cytokinins, SAs, and gibberellins were found in all tissues while auxins and tJA were observed only in the leaves. ABA was found in leaves and roots, but not in root tips. The method we used is efficient, precise, and appropriate to study citrus phytohormonal profiles to understand their crosstalk and responses to environmental and biological stresses.
Rice is the staple food crop for a large part of the human population in the world today. Rice bl... more Rice is the staple food crop for a large part of the human population in the world today. Rice blast caused by Pyricularia grisea (Cooke) Sacc. is the most important and threatening disease that attack rice. Failures of entire rice crops have resulted directly from rice blast epidemics. Improvement of rice production can be achieved through many factors, such as nitrogen fertilization and replacement of the traditional cultivated varieties by new high yielding ones in the suitable dates of sowing. A study was carried out in 2009 and 2010 seasons to understand the effect of nitrogen application rates and sowing dates on the development of rice blast under Egyptian conditions. Nine rice isolates were identified as 4 races and identified as IE (11.11%), IG (11.11%), IH (66.67%) and II (11.11%). In both seasons, the results showed that only four cultivars (Giza 171, Sakha 101, Sakha 104 and Reiho ) were susceptible to P. grisea, while Giza 177, Giza 178, Giza 182, Sakha 102, Sakha 103 and Hybrid1 were resistant. Additionally, increasing N-rates from zero to 40, 60 and 80 N unit/feddan resulted in a significant progressive increase in all disease characters in both seasons. The resistant cultivar Hybrid1 recorded the highest values for grain yield and its components. Under all N-rates, leaf blast infection severity on the four susceptible cultivars started in the first score (June 10th 2009 and June 05th 2010). The infection increased by time to reach its maximum in the fourth score in both seasons, then decreased again in the 5th and 6th scores. High significant correlations were obtained in general between disease parameters and yield components for susceptible cultivars. The regression coefficients between grain yield and each of the studied parameters i.e. leaf blast infection severity (LBIS) and panicle blast infection severity (PBIS) ranged from significant to highly significant for the four susceptible rice cultivars. The results also revealed that Reiho cultivar has the highest LBIS, while the highest leaf blast infection percentage (LBIP) was recorded by Sakha 104 in both seasons. Also, Sakha 104 has the highest numerical values of PBIS, panicle blast infection percentage (PBIP) and flag leaf collar rot infection (FLCRI) in both seasons. The resistant cultivar Hybrid1 recorded the highest values for grain yield and some of its components. Lesion size (length and width), lesion area, damage area and area under disease progress curve (AUDPC) were highly detected for Giza 171 in both seasons. Based on these results, it can be concluded that an integrated management program should be implemented to control rice blast disease effectively. This program includes widely cultivation of resistant rice cultivars such as Hybrid1 and in the same time, the susceptible cultivars i.e. Giza 171, Sakha 101, Sakha 104 and Reiho must be banned. Furthermore, this study also revealed that high application doses of nitrogen fertilizers and late sowing dates are not recommended especially with the highly susceptible cultivars.
Volatile organic compounds (VOC) play an important role in protecting plants from insect and path... more Volatile organic compounds (VOC) play an important role in protecting plants from insect and pathogen attack. In this study, we investigated the leaf volatile profiles of 14 citrus varieties. The VOC in citrus leaves were extracted with n-hexane and analyzed using gas chromatography-mass spectrometry (GC-MS). Overall, 4six volatile compounds were identified in the n-hexane extract from citrus leaves. Most of the detected compounds belonged to 3 main groups (monoterpenes, sesquiterpenes, and aliphatic aldehydes). Principle component analysis was used to examine the relative distribution of the studied varieties to each other. Interestingly, volatile profiles of varieties that are tolerant to Candidatus Liberibacter asiaticus (CLas) were different from those of the susceptible ones. Tolerant and moderately tolerant cultivars contained relatively higher amounts of volatiles than susceptible varieties. In addition, tolerant varieties were also higher in specific compounds which are known for their antimicrobial activities. These compounds include Aldehydes (undecanal, neral, geranial, and citronellal) and some monoterpenes such as linalool, d-limonene, myrcene, a- and b- phellandrene. In addition, some sesquiterpene compounds including t-caryophellene, g-elemene, b-elemene, germacrene D, and geranyl acetate were higher in tolerant and moderately tolerant cultivars. Severinia buxifolia which is known for its tolerance to CLas and many other pathogens contained higher levels of santalenes and coumarins. Our results indicated that citrus leaf volatiles might play a role in citrus tolerance to CLas. The results of this study may help in understanding of the mechanism of citrus tolerance against CLas.
Phytohormones mainly affect plant development and trigger varied responses to biotic and abiotic ... more Phytohormones mainly affect plant development and trigger varied responses to biotic and abiotic stresses. The sensitivity of methods used to profile phytohormones is a vital factor that affects the results. We used an improved GC–MS-based method in the selective ion-monitoring (SIM) mode to study the phytohormone profiling in citrus tissues. One extraction solvent mixture and two derivatization reagents were used, methyl chloroformate (MCF) and N-Methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA). The method showed a low limit of detection and low limit of quantification with high extraction recovery percentage and reproducibility. Overall, we detected 13 phytohormones belonging to six different groups. Auxins, SAs, tJA, and ABA were detected after derivatization with MCF while cytokinins and GAs were detected after derivatization with MSTFA. Cytokinins, SAs, and gibberellins were found in all tissues while auxins and tJA were observed only in the leaves. ABA was found in leaves and roots, but not in root tips. The method we used is efficient, precise, and appropriate to study citrus phytohormonal profiles to understand their crosstalk and responses to environmental and biological stresses.
Rice is the staple food crop for a large part of the human population in the world today. Rice bl... more Rice is the staple food crop for a large part of the human population in the world today. Rice blast caused by Pyricularia grisea (Cooke) Sacc. is the most important and threatening disease that attack rice. Failures of entire rice crops have resulted directly from rice blast epidemics. Improvement of rice production can be achieved through many factors, such as nitrogen fertilization and replacement of the traditional cultivated varieties by new high yielding ones in the suitable dates of sowing. A study was carried out in 2009 and 2010 seasons to understand the effect of nitrogen application rates and sowing dates on the development of rice blast under Egyptian conditions. Nine rice isolates were identified as 4 races and identified as IE (11.11%), IG (11.11%), IH (66.67%) and II (11.11%). In both seasons, the results showed that only four cultivars (Giza 171, Sakha 101, Sakha 104 and Reiho ) were susceptible to P. grisea, while Giza 177, Giza 178, Giza 182, Sakha 102, Sakha 103 and Hybrid1 were resistant. Additionally, increasing N-rates from zero to 40, 60 and 80 N unit/feddan resulted in a significant progressive increase in all disease characters in both seasons. The resistant cultivar Hybrid1 recorded the highest values for grain yield and its components. Under all N-rates, leaf blast infection severity on the four susceptible cultivars started in the first score (June 10th 2009 and June 05th 2010). The infection increased by time to reach its maximum in the fourth score in both seasons, then decreased again in the 5th and 6th scores. High significant correlations were obtained in general between disease parameters and yield components for susceptible cultivars. The regression coefficients between grain yield and each of the studied parameters i.e. leaf blast infection severity (LBIS) and panicle blast infection severity (PBIS) ranged from significant to highly significant for the four susceptible rice cultivars. The results also revealed that Reiho cultivar has the highest LBIS, while the highest leaf blast infection percentage (LBIP) was recorded by Sakha 104 in both seasons. Also, Sakha 104 has the highest numerical values of PBIS, panicle blast infection percentage (PBIP) and flag leaf collar rot infection (FLCRI) in both seasons. The resistant cultivar Hybrid1 recorded the highest values for grain yield and some of its components. Lesion size (length and width), lesion area, damage area and area under disease progress curve (AUDPC) were highly detected for Giza 171 in both seasons. Based on these results, it can be concluded that an integrated management program should be implemented to control rice blast disease effectively. This program includes widely cultivation of resistant rice cultivars such as Hybrid1 and in the same time, the susceptible cultivars i.e. Giza 171, Sakha 101, Sakha 104 and Reiho must be banned. Furthermore, this study also revealed that high application doses of nitrogen fertilizers and late sowing dates are not recommended especially with the highly susceptible cultivars.
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A study was carried out in 2009 and 2010 seasons to understand the effect of nitrogen application rates and sowing dates on the development of rice blast under Egyptian conditions.
Nine rice isolates were identified as 4 races and identified as IE (11.11%), IG (11.11%), IH (66.67%) and II (11.11%).
In both seasons, the results showed that only four cultivars (Giza 171, Sakha 101, Sakha 104 and Reiho ) were susceptible to P. grisea, while Giza 177, Giza 178, Giza 182, Sakha 102, Sakha 103 and Hybrid1 were resistant. Additionally, increasing N-rates from zero to 40, 60 and 80 N unit/feddan resulted in a significant progressive increase in all disease characters in both seasons. The resistant cultivar Hybrid1 recorded the highest values for grain yield and its components. Under all N-rates, leaf blast infection severity on the four susceptible cultivars started in the first score (June 10th 2009 and June 05th 2010). The infection increased by time to reach its maximum in the fourth score in both seasons, then decreased again in the 5th and 6th scores. High significant correlations were obtained in general between disease parameters and yield components for susceptible cultivars. The regression coefficients between grain yield and each of the studied parameters i.e. leaf blast infection severity (LBIS) and panicle blast infection severity (PBIS) ranged from significant to highly significant for the four susceptible rice cultivars. The results also revealed that Reiho cultivar has the highest LBIS, while the highest leaf blast infection percentage (LBIP) was recorded by Sakha 104 in both seasons. Also, Sakha 104 has the highest numerical values of PBIS, panicle blast infection percentage (PBIP) and flag leaf collar rot infection (FLCRI) in both seasons. The resistant cultivar Hybrid1 recorded the highest values for grain yield and some of its components. Lesion size (length and width), lesion area, damage area and area under disease progress curve (AUDPC) were highly detected for Giza 171 in both seasons.
Based on these results, it can be concluded that an integrated management program should be implemented to control rice blast disease effectively. This program includes widely cultivation of resistant rice cultivars such as Hybrid1 and in the same time, the susceptible cultivars i.e. Giza 171, Sakha 101, Sakha 104 and Reiho must be banned. Furthermore, this study also revealed that high application doses of nitrogen fertilizers and late sowing dates are not recommended especially with the highly susceptible cultivars.
A study was carried out in 2009 and 2010 seasons to understand the effect of nitrogen application rates and sowing dates on the development of rice blast under Egyptian conditions.
Nine rice isolates were identified as 4 races and identified as IE (11.11%), IG (11.11%), IH (66.67%) and II (11.11%).
In both seasons, the results showed that only four cultivars (Giza 171, Sakha 101, Sakha 104 and Reiho ) were susceptible to P. grisea, while Giza 177, Giza 178, Giza 182, Sakha 102, Sakha 103 and Hybrid1 were resistant. Additionally, increasing N-rates from zero to 40, 60 and 80 N unit/feddan resulted in a significant progressive increase in all disease characters in both seasons. The resistant cultivar Hybrid1 recorded the highest values for grain yield and its components. Under all N-rates, leaf blast infection severity on the four susceptible cultivars started in the first score (June 10th 2009 and June 05th 2010). The infection increased by time to reach its maximum in the fourth score in both seasons, then decreased again in the 5th and 6th scores. High significant correlations were obtained in general between disease parameters and yield components for susceptible cultivars. The regression coefficients between grain yield and each of the studied parameters i.e. leaf blast infection severity (LBIS) and panicle blast infection severity (PBIS) ranged from significant to highly significant for the four susceptible rice cultivars. The results also revealed that Reiho cultivar has the highest LBIS, while the highest leaf blast infection percentage (LBIP) was recorded by Sakha 104 in both seasons. Also, Sakha 104 has the highest numerical values of PBIS, panicle blast infection percentage (PBIP) and flag leaf collar rot infection (FLCRI) in both seasons. The resistant cultivar Hybrid1 recorded the highest values for grain yield and some of its components. Lesion size (length and width), lesion area, damage area and area under disease progress curve (AUDPC) were highly detected for Giza 171 in both seasons.
Based on these results, it can be concluded that an integrated management program should be implemented to control rice blast disease effectively. This program includes widely cultivation of resistant rice cultivars such as Hybrid1 and in the same time, the susceptible cultivars i.e. Giza 171, Sakha 101, Sakha 104 and Reiho must be banned. Furthermore, this study also revealed that high application doses of nitrogen fertilizers and late sowing dates are not recommended especially with the highly susceptible cultivars.