One hundred twenty-five endophytic microorganisms were isolated from the roots,stems,and leaves of four prominent rice cultivars growing in temperate regions.Their potential to combat rice blast disease and promote pl...One hundred twenty-five endophytic microorganisms were isolated from the roots,stems,and leaves of four prominent rice cultivars growing in temperate regions.Their potential to combat rice blast disease and promote plant growth was investigated.The dual culture tests highlighted the strong antagonistic activity of five fungal(ranging from 89%–70%)and five bacterial(72%–61%)endophytes.Subsequent examination focused on volatile compounds produced by selected isolates to counter the blast pathogen.Among these,the highest chitinase(13.76μg mL−1)and siderophore(56.64%),was exhibited by Aspergillus flavus,and the highest HCN production was shown by Stenotrophomonas maltophilia(36.15μM mL−1).In terms of growth promotion traits,Aspergillus flavus and Enterobacter cloacae excelled in activities viz,phosphorous solubilization,ammonia production,auxin and gibberellic acid production,and nitrogen fixation.The Identity of these endophytes was confirmed through molecular analysis as Trichoderma afroharzianum,Trichoderma harzianum,Penicillium rubens,Aspergillus flavus,Stenotrophomonas rhizophila,Stenotrophomonas maltophilia,Bacillus cereus,Enterobacter cloacae,and Bacillus licheniformis.Under greenhouse conditions,the highest disease control was shown by isolate Bacillus licheniformis and A.flavus with an inhibition of 79%,followed by S.rhizophila(77%)and T.afroharzianum(73%).The overall results of this study showed that Bacillus licheniformis and Stenotrophomonas rhizophila have great potential to be used as bio-stimulant and biocontrol agents to manage rice blast disease.展开更多
Abiotic stresses including drought,salinity,heat,cold,flooding,and ultraviolet radiation causes crop losses worldwide.In recent times,preventing these crop losses and producing more food and feed to meet the demands o...Abiotic stresses including drought,salinity,heat,cold,flooding,and ultraviolet radiation causes crop losses worldwide.In recent times,preventing these crop losses and producing more food and feed to meet the demands of ever-increasing human populations have gained unprecedented importance.However,the proportion of agricultural lands facing multiple abiotic stresses is expected only to rise under a changing global climate fueled by anthropogenic activities.Identifying the mechanisms developed and deployed by plants to counteract abiotic stresses and maintain their growth and survival under harsh conditions thus holds great significance.Recent investigations have shown that phytohormones,including the classical auxins,cytokinins,ethylene,and gibberellins,and newer members including brassinosteroids,jasmonates,and strigolactones may prove to be important metabolic engineering targets for producing abiotic stress-tolerant crop plants.In this review,we summarize and critically assess the roles that phytohormones play in plant growth and development and abiotic stress tolerance,besides their engineering for conferring abiotic stress tolerance in transgenic crops.We also describe recent successes in identifying the roles of phytohormones under stressful conditions.We conclude by describing the recent progress and future prospects including limitations and challenges of phytohormone engineering for inducing abiotic stress tolerance in crop plants.展开更多
An inhabitant of north western Himalayan region and a gynodioceious plant having a lot of medicinal properties, Valeriana jatamansi Jones (Valerianaceae) is an enlisted endangered plant in the world. It was introduced...An inhabitant of north western Himalayan region and a gynodioceious plant having a lot of medicinal properties, Valeriana jatamansi Jones (Valerianaceae) is an enlisted endangered plant in the world. It was introduced in the research station of North Bengal Agricultural University (27.06°N 88.47°E) situated in north eastern Himalayan region of Darjeeling district in the state of West Bengal from Sikkim Sangtok (27°25'N 88°31'E) of north Sikkim area in India for the purpose of conservation. As we noticed some irregular development of floral organs, we investigated some pertinent questions regarding ecological aberrations found in plants. We found plants introduced in north eastern Himalayan region changed their homology of number flower petals and position of stamens seen naturally in north western Himalayan region as per the reports. Was there any genetic or extreme environmental stress condition caused a sudden change in floral structure as it is generally known as a rare phenomenon and frequently not seen? What were the correlations of different floral parts and fitness of population in different morphotypes? We predicted possible outcomes of seed setting by univariate regression models in a particular environment in addition to this investigation. We proposed three models of heterozygousity for answering the reasons of unstable floral form from a general known floral form, where silent mutations help the plants to survive in adverse conditions in spite of deformed or variable formed of floral morphology.展开更多
Molecular mechanisms of hybrid breakdown associated with sterility (F<sub>2</sub> sterility) are poorly understood as compared with those of F<sub>1</sub> hybrid sterility. Previously, we chara...Molecular mechanisms of hybrid breakdown associated with sterility (F<sub>2</sub> sterility) are poorly understood as compared with those of F<sub>1</sub> hybrid sterility. Previously, we characterized three unlinked epistatic loci, hybrid sterility-a1 (hsa1), hsa2, and hsa3, responsible for the F<sub>2</sub> sterility in a cross between Oryza sativa ssp. indica and japonica. In this study, we identified that the hsa1 locus contains two interacting genes, HSA1a and HSA1b, within a 30-kb region. HSA1a-j (japonica allele) encodes a highly conserved plant-specific domain of unknown function protein (DUF1618), whereasthe indica allele (HSA1a-i<sup>s</sup>) has two deletion mutations that cause disruption of domain structure. The second gene, HSA1b-i<sup>s</sup>, encodes an uncharacterized proteinwith some similarity to a nucleotide-binding protein. Homozygous introgression of indica HSA1a-i<sup>s</sup>-HSA1b-i<sup>s</sup> alleles into japonica showed female gamete abortion at an early mitotic stage. The fact that the recombinant haplotype HSA1a-j-HSA1b-i<sup>s</sup> caused semi-sterility in the heterozygous state with the HSA1a-i<sup>s</sup>-HSA1b-i<sup>s</sup> haplotype suggests that variation in the hsa1 locus is a possible cause of the wide-spectrum sterility barriers seen in F<sub>1</sub> hybrids and successive generations in rice. We propose a simple genetic model to explain how a single causal mechanism can drive both F<sub>1</sub> and F<sub>2</sub> hybrid sterility.展开更多
基金The authors extend their appreciation to the Researchers Supporting Project Number(RSP2023R298),King Saud University,Riyadh,Saudi Arabia.
文摘One hundred twenty-five endophytic microorganisms were isolated from the roots,stems,and leaves of four prominent rice cultivars growing in temperate regions.Their potential to combat rice blast disease and promote plant growth was investigated.The dual culture tests highlighted the strong antagonistic activity of five fungal(ranging from 89%–70%)and five bacterial(72%–61%)endophytes.Subsequent examination focused on volatile compounds produced by selected isolates to counter the blast pathogen.Among these,the highest chitinase(13.76μg mL−1)and siderophore(56.64%),was exhibited by Aspergillus flavus,and the highest HCN production was shown by Stenotrophomonas maltophilia(36.15μM mL−1).In terms of growth promotion traits,Aspergillus flavus and Enterobacter cloacae excelled in activities viz,phosphorous solubilization,ammonia production,auxin and gibberellic acid production,and nitrogen fixation.The Identity of these endophytes was confirmed through molecular analysis as Trichoderma afroharzianum,Trichoderma harzianum,Penicillium rubens,Aspergillus flavus,Stenotrophomonas rhizophila,Stenotrophomonas maltophilia,Bacillus cereus,Enterobacter cloacae,and Bacillus licheniformis.Under greenhouse conditions,the highest disease control was shown by isolate Bacillus licheniformis and A.flavus with an inhibition of 79%,followed by S.rhizophila(77%)and T.afroharzianum(73%).The overall results of this study showed that Bacillus licheniformis and Stenotrophomonas rhizophila have great potential to be used as bio-stimulant and biocontrol agents to manage rice blast disease.
文摘Abiotic stresses including drought,salinity,heat,cold,flooding,and ultraviolet radiation causes crop losses worldwide.In recent times,preventing these crop losses and producing more food and feed to meet the demands of ever-increasing human populations have gained unprecedented importance.However,the proportion of agricultural lands facing multiple abiotic stresses is expected only to rise under a changing global climate fueled by anthropogenic activities.Identifying the mechanisms developed and deployed by plants to counteract abiotic stresses and maintain their growth and survival under harsh conditions thus holds great significance.Recent investigations have shown that phytohormones,including the classical auxins,cytokinins,ethylene,and gibberellins,and newer members including brassinosteroids,jasmonates,and strigolactones may prove to be important metabolic engineering targets for producing abiotic stress-tolerant crop plants.In this review,we summarize and critically assess the roles that phytohormones play in plant growth and development and abiotic stress tolerance,besides their engineering for conferring abiotic stress tolerance in transgenic crops.We also describe recent successes in identifying the roles of phytohormones under stressful conditions.We conclude by describing the recent progress and future prospects including limitations and challenges of phytohormone engineering for inducing abiotic stress tolerance in crop plants.
文摘An inhabitant of north western Himalayan region and a gynodioceious plant having a lot of medicinal properties, Valeriana jatamansi Jones (Valerianaceae) is an enlisted endangered plant in the world. It was introduced in the research station of North Bengal Agricultural University (27.06°N 88.47°E) situated in north eastern Himalayan region of Darjeeling district in the state of West Bengal from Sikkim Sangtok (27°25'N 88°31'E) of north Sikkim area in India for the purpose of conservation. As we noticed some irregular development of floral organs, we investigated some pertinent questions regarding ecological aberrations found in plants. We found plants introduced in north eastern Himalayan region changed their homology of number flower petals and position of stamens seen naturally in north western Himalayan region as per the reports. Was there any genetic or extreme environmental stress condition caused a sudden change in floral structure as it is generally known as a rare phenomenon and frequently not seen? What were the correlations of different floral parts and fitness of population in different morphotypes? We predicted possible outcomes of seed setting by univariate regression models in a particular environment in addition to this investigation. We proposed three models of heterozygousity for answering the reasons of unstable floral form from a general known floral form, where silent mutations help the plants to survive in adverse conditions in spite of deformed or variable formed of floral morphology.
文摘Molecular mechanisms of hybrid breakdown associated with sterility (F<sub>2</sub> sterility) are poorly understood as compared with those of F<sub>1</sub> hybrid sterility. Previously, we characterized three unlinked epistatic loci, hybrid sterility-a1 (hsa1), hsa2, and hsa3, responsible for the F<sub>2</sub> sterility in a cross between Oryza sativa ssp. indica and japonica. In this study, we identified that the hsa1 locus contains two interacting genes, HSA1a and HSA1b, within a 30-kb region. HSA1a-j (japonica allele) encodes a highly conserved plant-specific domain of unknown function protein (DUF1618), whereasthe indica allele (HSA1a-i<sup>s</sup>) has two deletion mutations that cause disruption of domain structure. The second gene, HSA1b-i<sup>s</sup>, encodes an uncharacterized proteinwith some similarity to a nucleotide-binding protein. Homozygous introgression of indica HSA1a-i<sup>s</sup>-HSA1b-i<sup>s</sup> alleles into japonica showed female gamete abortion at an early mitotic stage. The fact that the recombinant haplotype HSA1a-j-HSA1b-i<sup>s</sup> caused semi-sterility in the heterozygous state with the HSA1a-i<sup>s</sup>-HSA1b-i<sup>s</sup> haplotype suggests that variation in the hsa1 locus is a possible cause of the wide-spectrum sterility barriers seen in F<sub>1</sub> hybrids and successive generations in rice. We propose a simple genetic model to explain how a single causal mechanism can drive both F<sub>1</sub> and F<sub>2</sub> hybrid sterility.
