Cadmium(Cd)is a toxic heavy metal occurring in the environment naturally and is also generated through various anthropogenic sources and acts as a pollutant.Human health is affected by Cd pollution in farmland soils b...Cadmium(Cd)is a toxic heavy metal occurring in the environment naturally and is also generated through various anthropogenic sources and acts as a pollutant.Human health is affected by Cd pollution in farmland soils because food is the main source of Cd intake in the non-smoking population.For crops,Cd toxicity may result from a disturbance in uptake and translocation of mineral nutrients and disturbance in plant metabolism,inhibiting plant growth and development.However,plants have Cd tolerance mechanisms,including restricted Cd uptake,decreased Cd root-to-shoot translocation,enhanced antioxidant enzyme activities,and increased production of phytochelatins.Furthermore,optimal supply of mineral nutrients is one of the strategies to alleviate the damaging effects of Cd on plants and to avoid its entry into the food chain.The emerging molecular knowledge contributes to understanding Cd uptake,translocation,and remobilization in plants.In this review,Cd toxicity and tolerance mechanisms,agricultural practices to minimize Cd accumulation,Cd competition with essential elements(calcium,copper,iron,zinc,and manganese),and genes associated with Cd uptake are discussed in detail,especially regarding how these mineral nutrients and genes play a role in decreasing Cd uptake and accumulation in crop plants.展开更多
Tomato bacterial wilt caused by Ralstonia solanacearum seriously threats tomato growth in tropical and temperate regions around the world.This study reported an antagonistic bacterial strain, Bacillus amyloliquefacien...Tomato bacterial wilt caused by Ralstonia solanacearum seriously threats tomato growth in tropical and temperate regions around the world.This study reported an antagonistic bacterial strain, Bacillus amyloliquefaciens strain SQRT3, isolated from the rhizosphere soil of tomato plants, which strongly inhibited in vitro growth of pathogenic R.solanacearum.The suppression of tomato bacterial wilt by strain SQRT3 was demonstrated under greenhouse conditions.Additionally, induced systemic resistance(ISR) in tomato as one of the potential disease suppression mechanisms was investigated in the plants inoculated with the isolated bacterial strain SQRT3.The results showed that strain SQRT3 applied with R.solanacearum by drenching significantly reduced tomato bacterial wilt by 68.1% biocontrol efficiency(BE) and suppressed the R.solanacearum populations in the rhizosphere soil compared to the control only drenched with R.solanacearum.The BE of the isolated bacterial strain SQRT3 against tomato wilt increased to 84.1%by root-dipping.Tomato plants treated with both strain SQRT3 and R.solanacearum showed increases in activities of peroxidase and polyphenol oxidase compared with other treatments.The application of strain SQRT3 reduced membrane lipid peroxidation in tomato leaves.The expressions of marker genes for jasmonic acid-and salicylic acid-dependent signaling pathways were faster and stronger in tomato plants treated with both strain SQRT3 and R.solanacearum than in plants treated with either R.solanacearum or strain SQRT3 alone.Collectively, the findings indicated that strain SQRT3 can effectively control tomato wilt.展开更多
Erwinia amylovora species were isolated from the blossoms, exudates, infected fruits, leaves and bent branches of diseased apple, pear and hawthorn trees, selected in the Chy, Osh and Jalal Abad regions. Biochemical a...Erwinia amylovora species were isolated from the blossoms, exudates, infected fruits, leaves and bent branches of diseased apple, pear and hawthorn trees, selected in the Chy, Osh and Jalal Abad regions. Biochemical and pathogenicity tests, alongside PCR analyses, were conducted to identify the local isolates of Erwinia amylovora. The alternative antagonistic microorganisms which combat bacterium E. amylovora were tested within in vitro and in vivo conditions. The results revealed the ability of Streptomyces antagonistic bacteria to decrease fire blight severity on pear and apple trees during the first stage of the fire blight disease in leaf tissues. Streptomyces strain C1-4 suppressed E. amylovora disease symptoms in the leaf tissues and excised apple and pear shoots. The incidence of fire blight on leaves was reduced by about 70% with two applications of bacterial antagonists. Further studies at different locations in Kyrgyzstan, using large scale application, would allow for stronger recommendations to be made, including studies and recommendations on their ability to prevent disease and to use them as main components in an integrated pest management program.展开更多
To assess the effect of rice straw mulching on changes of antagonistic bacteria and the incidence of wheat sharp eyespot, a multi-year field study was performed to compare unmulched plots and the plots mulched with ri...To assess the effect of rice straw mulching on changes of antagonistic bacteria and the incidence of wheat sharp eyespot, a multi-year field study was performed to compare unmulched plots and the plots mulched with rice straw for two or three years. Bacterial and fungal populations were evaluated in the cultures prepared from the wheat rhizosphere and bulk soils. Rice straw mulching increased the number of pseudomonas colony forming units in wheat rhizosphere and bulk soils. The proportion of total bacteria that were fluorescent pseudomonads was higher in mulched than in unmulched soil. Bacterial isolates antagonistic to Rhizoctonia cerealis were identified using an inhibition zone test. A series of these isolates were typed by partial sequencing of the 16S rRNA gene. Pseudomonads had higher antagonistic activity against R. cerealis than other species, and more than 80% of rhizosphere fluorescent pseudomonads were antagonistic to R. eerealis. The disease indices were lower in the mulched plots than in the unmulched control. These results suggest that rice straw mulching in a rice-wheat rotation increases the number of fluorescent pseudomonads. Additionally, these fluorescent pseudomonads may contribute to the control of wheat sharp eyespot.展开更多
基金supported by the Science and Technology Innovation Fund of Henan Agricultural University,China(No.KJCX2019A19)the National Key R&D Program of China(No.2017YFD0201700)the Doctoral Scientific Research Foundation of Henan Agricultural University,China(No.30500592)。
文摘Cadmium(Cd)is a toxic heavy metal occurring in the environment naturally and is also generated through various anthropogenic sources and acts as a pollutant.Human health is affected by Cd pollution in farmland soils because food is the main source of Cd intake in the non-smoking population.For crops,Cd toxicity may result from a disturbance in uptake and translocation of mineral nutrients and disturbance in plant metabolism,inhibiting plant growth and development.However,plants have Cd tolerance mechanisms,including restricted Cd uptake,decreased Cd root-to-shoot translocation,enhanced antioxidant enzyme activities,and increased production of phytochelatins.Furthermore,optimal supply of mineral nutrients is one of the strategies to alleviate the damaging effects of Cd on plants and to avoid its entry into the food chain.The emerging molecular knowledge contributes to understanding Cd uptake,translocation,and remobilization in plants.In this review,Cd toxicity and tolerance mechanisms,agricultural practices to minimize Cd accumulation,Cd competition with essential elements(calcium,copper,iron,zinc,and manganese),and genes associated with Cd uptake are discussed in detail,especially regarding how these mineral nutrients and genes play a role in decreasing Cd uptake and accumulation in crop plants.
基金financially supported by the Science and Technology Program of Jiangsu Province,China(No.BE2014398)the National Natural Science Foundation of China(No.41571242)
文摘Tomato bacterial wilt caused by Ralstonia solanacearum seriously threats tomato growth in tropical and temperate regions around the world.This study reported an antagonistic bacterial strain, Bacillus amyloliquefaciens strain SQRT3, isolated from the rhizosphere soil of tomato plants, which strongly inhibited in vitro growth of pathogenic R.solanacearum.The suppression of tomato bacterial wilt by strain SQRT3 was demonstrated under greenhouse conditions.Additionally, induced systemic resistance(ISR) in tomato as one of the potential disease suppression mechanisms was investigated in the plants inoculated with the isolated bacterial strain SQRT3.The results showed that strain SQRT3 applied with R.solanacearum by drenching significantly reduced tomato bacterial wilt by 68.1% biocontrol efficiency(BE) and suppressed the R.solanacearum populations in the rhizosphere soil compared to the control only drenched with R.solanacearum.The BE of the isolated bacterial strain SQRT3 against tomato wilt increased to 84.1%by root-dipping.Tomato plants treated with both strain SQRT3 and R.solanacearum showed increases in activities of peroxidase and polyphenol oxidase compared with other treatments.The application of strain SQRT3 reduced membrane lipid peroxidation in tomato leaves.The expressions of marker genes for jasmonic acid-and salicylic acid-dependent signaling pathways were faster and stronger in tomato plants treated with both strain SQRT3 and R.solanacearum than in plants treated with either R.solanacearum or strain SQRT3 alone.Collectively, the findings indicated that strain SQRT3 can effectively control tomato wilt.
文摘Erwinia amylovora species were isolated from the blossoms, exudates, infected fruits, leaves and bent branches of diseased apple, pear and hawthorn trees, selected in the Chy, Osh and Jalal Abad regions. Biochemical and pathogenicity tests, alongside PCR analyses, were conducted to identify the local isolates of Erwinia amylovora. The alternative antagonistic microorganisms which combat bacterium E. amylovora were tested within in vitro and in vivo conditions. The results revealed the ability of Streptomyces antagonistic bacteria to decrease fire blight severity on pear and apple trees during the first stage of the fire blight disease in leaf tissues. Streptomyces strain C1-4 suppressed E. amylovora disease symptoms in the leaf tissues and excised apple and pear shoots. The incidence of fire blight on leaves was reduced by about 70% with two applications of bacterial antagonists. Further studies at different locations in Kyrgyzstan, using large scale application, would allow for stronger recommendations to be made, including studies and recommendations on their ability to prevent disease and to use them as main components in an integrated pest management program.
基金Supported by the National Key Technology R&D Program of China (No. 2006BAD08A05)the National Special Research Programs for Non-Profit Trades of China (No. nyhyzx3-16)
文摘To assess the effect of rice straw mulching on changes of antagonistic bacteria and the incidence of wheat sharp eyespot, a multi-year field study was performed to compare unmulched plots and the plots mulched with rice straw for two or three years. Bacterial and fungal populations were evaluated in the cultures prepared from the wheat rhizosphere and bulk soils. Rice straw mulching increased the number of pseudomonas colony forming units in wheat rhizosphere and bulk soils. The proportion of total bacteria that were fluorescent pseudomonads was higher in mulched than in unmulched soil. Bacterial isolates antagonistic to Rhizoctonia cerealis were identified using an inhibition zone test. A series of these isolates were typed by partial sequencing of the 16S rRNA gene. Pseudomonads had higher antagonistic activity against R. cerealis than other species, and more than 80% of rhizosphere fluorescent pseudomonads were antagonistic to R. eerealis. The disease indices were lower in the mulched plots than in the unmulched control. These results suggest that rice straw mulching in a rice-wheat rotation increases the number of fluorescent pseudomonads. Additionally, these fluorescent pseudomonads may contribute to the control of wheat sharp eyespot.
