The“Green Revolution”spread worldwide due to the propagation of the causative gene of a semi-dwarf variety of wheat Norin 10 mutant,which was bred by Dr.Gonjiro Inazuka in 1935.This dwarf variety was later used to h...The“Green Revolution”spread worldwide due to the propagation of the causative gene of a semi-dwarf variety of wheat Norin 10 mutant,which was bred by Dr.Gonjiro Inazuka in 1935.This dwarf variety was later used to help produce high-yielding,semi-dwarf winter wheat varieties by Prof.Orille Vogel,which were then crossed with Mexican wheat varieties to produce a dwarf variety by Dr.Norman Borlaug in 1953.Dwarf wheat is more productive because it is less prone to lodging and allows higher nitrogen fertilizer application.The introduction of dwarf wheat to agriculture later contributed significantly to improve food security in developing countries by increasing world wheat productivity five-fold.The leader of the project,Dr.Borlaug,was awarded the Nobel Peace Prize for his work and is known as the father of the Green Revolution.Studies on wheat semi-dwarfism derived from Norin 10 by Prof.Mike Gale led to the molecular characterization of the Rht1 gene(Gale and Marshall,1976).In 1999,Prof.Harberd and his group identified the DELLA protein,a gibberellin(GA)signaling factor previously reported in Arabidopsis,as the causal gene corresponding to the phenotype Rht1 and demonstrated that variant forms of the GA–DELLA mechanism are crucial to yield(Peng et al.,1999).In rice,a GA biosynthesis mutant that exhibits a semi-dwarf phenotype due to stabilization of the rice DELLA protein SLR1 also played an important role in increasing yield(Sasaki et al.,2002).The induction of dwarfism through the use of GA biosynthesis inhibitors is also an important mechanism for increasing food production in wheat and rice(Rademacher,2000).However,this increase has recently reached a plateau.In addition,varieties used in the Green Revolution have low soil mineral nutrient(nitrogen)use efficiency(NUE)and rely on environmentally unsustainable fertilizer applications to achieve high yields.In this context,new approaches for increasing yields are essential for future food security by a way to coordinate high yield and NUE characteristics in cereal production.In 2018,Li et al.reported that the balanced opposing activities and physical interactions of the rice GROWTH-REGULATING FACTOR 4(GRF4)transcription factor and the growth inhibitor DELLA confer homeostatic co-regulation of growth and the metabolism of carbon and nitrogen(Li et al.,2018).The role of GRF4 is to enhance and combine the process of nitrogen assimilation,carbon fixation,and growth,while DELLA works in opposition to these functions.The accumulation of DELLA in Green Revolution varieties not only causes dwarfism and increases yield but also decreases the efficiency of nitrogen usage.Modulating the expression of GRF4 and rebalancing GRF4–DELLA toward GRF4 represent viable strategies to enhance nitrogen utilization efficiency and grain yield in Green Revolution cultivars.Therefore,GRF4 has the potential to contribute to further improving the productivity and sustainability of agriculture,which are key goals of the Green Revolution.However,a deeper understanding of the co-regulatory mechanisms of GRF4 that integrate growth,nitrogen assimilation,and carbon fixations is still necessary.展开更多
Strigolactones （SLs） are a novel class of plant hormones and rhizosphere communication signals, although the molecular mechanisms underlying their activities have not yet been fully determined. Nor is their applicat...Strigolactones （SLs） are a novel class of plant hormones and rhizosphere communication signals, although the molecular mechanisms underlying their activities have not yet been fully determined. Nor is their application in agriculture well developed. The importance of plant hormone agonists has been demonstrated in both basic and applied research, and chemicals that mimic strigolactone functions should greatly facilitate strigolactone research. Here, we report our discovery of a new phenoxyfuranone compound, 4-Br debranone （4BD）, that shows similar activity to that of the major strigolactone （SL） analog GR24 in many aspects of a biological assay on plants. 4BD strongly inhibited tiller bud outgrowth in the SL-deficient rice mutant d10 at the same concentration as GR24, with no adverse effects, even dur- ing prolonged cultivation. This result was also observed in the Arabidopsis thaliana SL-deficient mutants max1, max3, and max4. However, the application of 4BD to the Arabidopsis SL-insensitive mutant max2 induced no morphological changes in it. The expression of SL biosynthetic genes was also reduced by 4BD treatment, probably via negative feed- back regulation. However, in a seed germination assay on Striga hermonthica, a root parasitic plant, 4BD showed far less activity than GR24. These results suggest that 4BD is the first plant-specific strigolactone mimic.展开更多
Strigolactones,a class of plant hormones with multiple functions,mediate plant-plant and plantmicroorganism communications in the rhizosphere.In this study,we developed potent strigolactone antagonists,which covalentl...Strigolactones,a class of plant hormones with multiple functions,mediate plant-plant and plantmicroorganism communications in the rhizosphere.In this study,we developed potent strigolactone antagonists,which covalently bindto the strigolactone receptor D14,by preparing an array of triazole urea compounds.Using yeast two-hybrid and rice-tillering assays,we identified a triazole urea compound KK094 as a potent inhibitor of strigolactone receptors.Liquid chromatography-tandem mass spectrometry analysis and X-ray crystallography revealed that KK094 was hydrolyzed by D14,and that a reaction product of this degradation covalently binds to the Ser residue of the catalytic triad of D14.Furthermore,we identified two triazole urea compounds KK052 and KK073,whose effects on D14-D53/D14-SLR1 complex formation were opposite due to the absence (KK052)or presence (KK073)of a trifluoromethyl group on their phenyl ring.These results demonstrate that triazole urea compounds are potentially powerful tools for agricultural application and may be useful for the elucidation of the complicated mechanism underlying strigolactone perception.展开更多
We undertook a chemical genetics screen to identify chemical inhibitors of brassinosteroid （BR） action. From a chemical library of 10,000 small molecules, one compound was found to inhibit hypocotyl length and activ...We undertook a chemical genetics screen to identify chemical inhibitors of brassinosteroid （BR） action. From a chemical library of 10,000 small molecules, one compound was found to inhibit hypocotyl length and activate the expression of a BR-repressed reporter gene （CPD：：GUS） in Arabidopsis, and it was named brassinopride （BRP）. These effects of BRP could be reversed by co-treatment with brassinolide, suggesting that BRP either directly or indirectly inhibits BR biosynthesis. Interestingly, the compound causes exaggerated apical hooks, similar to that caused by ethylene treatment. The BRP-induced apical hook phenotype can be blocked by a chemical inhibitor of ethylene perception or an ethylene-insensitive mutant, suggesting that, in addition to inhibiting BR, BRP activates ethylene response. Analysis of BRP analogs provided clues about structural features important for its effects on two separate targets in the BR and ethylene pathways. Analyses of the responses of various BR and ethylene mutants to BRP, ethylene, and BR treatments revealed modes of cross-talk between ethylene and BR in dark-grown seedlings. Our results suggest that active downstream BR signaling, but not BR synthesis or a BR gradient, is required for ethylene-induced apical hook formation. The BRP-related compounds can be useful tools for manipulating plant growth and studying hormone interactions.展开更多
Zaxinone is an apocarotenoid regulatory metabolite required for normal rice growth and development.In addition,zaxinone has a large application potential in agriculture,due to its growth-promoting activity and capabil...Zaxinone is an apocarotenoid regulatory metabolite required for normal rice growth and development.In addition,zaxinone has a large application potential in agriculture,due to its growth-promoting activity and capability to alleviate infestation by the root parasitic plant Striga through decreasing strigolactone(SL)production.However,zaxinone is poorly accessible to the scientific community because of its laborious organic synthesis that impedes its further investigation and utilization.In this study,we developed easy-to-synthesize and highly efficient mimics of zaxinone(MiZax).We performed a structure-activity relationship study using a series of apocarotenoids distinguished from zaxinone by different structural features.Using the obtained results,we designed several phenyl-based compounds synthesized with a high-yield through a simple method.Activity tests showed that MiZax3 and MiZax5 exert zaxinone activity in rescuing root growth of a zaxinone-deficient rice mutant,promoting growth,and reducing SL content in roots and root exudates of wild-type plants.Moreover,these compounds were at least as efficient as zaxinone in suppressing transcript level of SL biosynthesis genes and in alleviating Striga infestation under greenhouse conditions,and did not negatively impact mycorrhization.Taken together,MiZax are a promising tool for elucidating zaxinone biology and investigating rice development,and suitable candidates for combating Striga and increasing crop growth.展开更多
Strigolactones(SLs)are plant hormones that regulate the branching of plants and seed germination stimulants of root parasitic plants.As root parasites are a great threat to agricultural production,the use of SL agonis...Strigolactones(SLs)are plant hormones that regulate the branching of plants and seed germination stimulants of root parasitic plants.As root parasites are a great threat to agricultural production,the use of SL agonists could be anticipated to provide an efficient method for regulating root parasites as suicidal germination inducers.A series of phenoxyfuranone-type SL mimics,termed debranones,has been reported to show potent bioactivities,including reduction of the tiller number on rice,and stimulation of seed germination in the root parasite Striga hermonthica.To exert both activities,two substituents on the phenyl ring of the molecules were important but at least a substituent at the 2-position must be an electron-withdrawing group.However,little is known about the effect of the properties of the substituents at the 2-position on bioactivities.Here,we found that different substituents at the 2-position give different preferences for bioactivities.Halogenated debranones were more effective than the others and SL agonist GR24 for inhibiting rice tiller but far less effective in the induction of S.hermonthica germination.Meanwhile,nitrile and methyl derivatives clearly stimulated the germination of S.hermonthica seeds.Although their IC_(50) values were 100 times higher than that of GR24 in the receptor competitive binding assay,their physiological activities were approximately 1/10 of GR24.These differences could be due to their uptake in plants and/or their physicochemical stability under our experimental conditions.These findings could support the design of more potent and selective SL agonists that could contribute to solving big agricultural issues.展开更多
Dear Editor,Most of the plant hormones found in flowering plants contribute to growth regulation in the moss Physcomitrella patens. This moss does not produce gibberellin （GA） （Figure 1A）. An ent-kaurene synthase ...Dear Editor,Most of the plant hormones found in flowering plants contribute to growth regulation in the moss Physcomitrella patens. This moss does not produce gibberellin （GA） （Figure 1A）. An ent-kaurene synthase （PpCPS/KS） and an ent-kaurene oxidase （PpKO） have been identified in P. patens, but in contrast to flowering plants, P. patens has no ent-kaurenoic acid oxidase （KAO） homologs （Hayashi et al., 2010; Miyazaki et al., 2011, Fiqure 1A）.展开更多
文摘The“Green Revolution”spread worldwide due to the propagation of the causative gene of a semi-dwarf variety of wheat Norin 10 mutant,which was bred by Dr.Gonjiro Inazuka in 1935.This dwarf variety was later used to help produce high-yielding,semi-dwarf winter wheat varieties by Prof.Orille Vogel,which were then crossed with Mexican wheat varieties to produce a dwarf variety by Dr.Norman Borlaug in 1953.Dwarf wheat is more productive because it is less prone to lodging and allows higher nitrogen fertilizer application.The introduction of dwarf wheat to agriculture later contributed significantly to improve food security in developing countries by increasing world wheat productivity five-fold.The leader of the project,Dr.Borlaug,was awarded the Nobel Peace Prize for his work and is known as the father of the Green Revolution.Studies on wheat semi-dwarfism derived from Norin 10 by Prof.Mike Gale led to the molecular characterization of the Rht1 gene(Gale and Marshall,1976).In 1999,Prof.Harberd and his group identified the DELLA protein,a gibberellin(GA)signaling factor previously reported in Arabidopsis,as the causal gene corresponding to the phenotype Rht1 and demonstrated that variant forms of the GA–DELLA mechanism are crucial to yield(Peng et al.,1999).In rice,a GA biosynthesis mutant that exhibits a semi-dwarf phenotype due to stabilization of the rice DELLA protein SLR1 also played an important role in increasing yield(Sasaki et al.,2002).The induction of dwarfism through the use of GA biosynthesis inhibitors is also an important mechanism for increasing food production in wheat and rice(Rademacher,2000).However,this increase has recently reached a plateau.In addition,varieties used in the Green Revolution have low soil mineral nutrient(nitrogen)use efficiency(NUE)and rely on environmentally unsustainable fertilizer applications to achieve high yields.In this context,new approaches for increasing yields are essential for future food security by a way to coordinate high yield and NUE characteristics in cereal production.In 2018,Li et al.reported that the balanced opposing activities and physical interactions of the rice GROWTH-REGULATING FACTOR 4(GRF4)transcription factor and the growth inhibitor DELLA confer homeostatic co-regulation of growth and the metabolism of carbon and nitrogen(Li et al.,2018).The role of GRF4 is to enhance and combine the process of nitrogen assimilation,carbon fixation,and growth,while DELLA works in opposition to these functions.The accumulation of DELLA in Green Revolution varieties not only causes dwarfism and increases yield but also decreases the efficiency of nitrogen usage.Modulating the expression of GRF4 and rebalancing GRF4–DELLA toward GRF4 represent viable strategies to enhance nitrogen utilization efficiency and grain yield in Green Revolution cultivars.Therefore,GRF4 has the potential to contribute to further improving the productivity and sustainability of agriculture,which are key goals of the Green Revolution.However,a deeper understanding of the co-regulatory mechanisms of GRF4 that integrate growth,nitrogen assimilation,and carbon fixations is still necessary.
文摘Strigolactones （SLs） are a novel class of plant hormones and rhizosphere communication signals, although the molecular mechanisms underlying their activities have not yet been fully determined. Nor is their application in agriculture well developed. The importance of plant hormone agonists has been demonstrated in both basic and applied research, and chemicals that mimic strigolactone functions should greatly facilitate strigolactone research. Here, we report our discovery of a new phenoxyfuranone compound, 4-Br debranone （4BD）, that shows similar activity to that of the major strigolactone （SL） analog GR24 in many aspects of a biological assay on plants. 4BD strongly inhibited tiller bud outgrowth in the SL-deficient rice mutant d10 at the same concentration as GR24, with no adverse effects, even dur- ing prolonged cultivation. This result was also observed in the Arabidopsis thaliana SL-deficient mutants max1, max3, and max4. However, the application of 4BD to the Arabidopsis SL-insensitive mutant max2 induced no morphological changes in it. The expression of SL biosynthetic genes was also reduced by 4BD treatment, probably via negative feed- back regulation. However, in a seed germination assay on Striga hermonthica, a root parasitic plant, 4BD showed far less activity than GR24. These results suggest that 4BD is the first plant-specific strigolactone mimic.
文摘Strigolactones,a class of plant hormones with multiple functions,mediate plant-plant and plantmicroorganism communications in the rhizosphere.In this study,we developed potent strigolactone antagonists,which covalently bindto the strigolactone receptor D14,by preparing an array of triazole urea compounds.Using yeast two-hybrid and rice-tillering assays,we identified a triazole urea compound KK094 as a potent inhibitor of strigolactone receptors.Liquid chromatography-tandem mass spectrometry analysis and X-ray crystallography revealed that KK094 was hydrolyzed by D14,and that a reaction product of this degradation covalently binds to the Ser residue of the catalytic triad of D14.Furthermore,we identified two triazole urea compounds KK052 and KK073,whose effects on D14-D53/D14-SLR1 complex formation were opposite due to the absence (KK052)or presence (KK073)of a trifluoromethyl group on their phenyl ring.These results demonstrate that triazole urea compounds are potentially powerful tools for agricultural application and may be useful for the elucidation of the complicated mechanism underlying strigolactone perception.
文摘We undertook a chemical genetics screen to identify chemical inhibitors of brassinosteroid （BR） action. From a chemical library of 10,000 small molecules, one compound was found to inhibit hypocotyl length and activate the expression of a BR-repressed reporter gene （CPD：：GUS） in Arabidopsis, and it was named brassinopride （BRP）. These effects of BRP could be reversed by co-treatment with brassinolide, suggesting that BRP either directly or indirectly inhibits BR biosynthesis. Interestingly, the compound causes exaggerated apical hooks, similar to that caused by ethylene treatment. The BRP-induced apical hook phenotype can be blocked by a chemical inhibitor of ethylene perception or an ethylene-insensitive mutant, suggesting that, in addition to inhibiting BR, BRP activates ethylene response. Analysis of BRP analogs provided clues about structural features important for its effects on two separate targets in the BR and ethylene pathways. Analyses of the responses of various BR and ethylene mutants to BRP, ethylene, and BR treatments revealed modes of cross-talk between ethylene and BR in dark-grown seedlings. Our results suggest that active downstream BR signaling, but not BR synthesis or a BR gradient, is required for ethylene-induced apical hook formation. The BRP-related compounds can be useful tools for manipulating plant growth and studying hormone interactions.
基金the Bill&Melinda Gates Foundation(grant no.OPP1194472)a Competitive Research Grant(CRG2017)to S.A.-B.from King Abdullah University of Science and Technology(KAUST)+2 种基金the Core Research for Evolutional Science and Technology(CREST)Programthe SATREPS Program of the Japan Science and Technology Agency(JST)JSPS Grant-in-Aid for Scientific Research(grant no.18H03939)to T.A.
文摘Zaxinone is an apocarotenoid regulatory metabolite required for normal rice growth and development.In addition,zaxinone has a large application potential in agriculture,due to its growth-promoting activity and capability to alleviate infestation by the root parasitic plant Striga through decreasing strigolactone(SL)production.However,zaxinone is poorly accessible to the scientific community because of its laborious organic synthesis that impedes its further investigation and utilization.In this study,we developed easy-to-synthesize and highly efficient mimics of zaxinone(MiZax).We performed a structure-activity relationship study using a series of apocarotenoids distinguished from zaxinone by different structural features.Using the obtained results,we designed several phenyl-based compounds synthesized with a high-yield through a simple method.Activity tests showed that MiZax3 and MiZax5 exert zaxinone activity in rescuing root growth of a zaxinone-deficient rice mutant,promoting growth,and reducing SL content in roots and root exudates of wild-type plants.Moreover,these compounds were at least as efficient as zaxinone in suppressing transcript level of SL biosynthesis genes and in alleviating Striga infestation under greenhouse conditions,and did not negatively impact mycorrhization.Taken together,MiZax are a promising tool for elucidating zaxinone biology and investigating rice development,and suitable candidates for combating Striga and increasing crop growth.
基金partly supported by a grant from the Core Research for Evolutional Science and Technology(CREST)Program of the Japan Science and Technology Agency(JST)the Japan International Cooperation Agency(JICA)+1 种基金JST under a joint program of Science and Technology Research Partnership for Sustainable Development(SATREPS)a JSPS Grant-in-Aid for Scientific Research(Grant no.18H03939 to TA).
文摘Strigolactones(SLs)are plant hormones that regulate the branching of plants and seed germination stimulants of root parasitic plants.As root parasites are a great threat to agricultural production,the use of SL agonists could be anticipated to provide an efficient method for regulating root parasites as suicidal germination inducers.A series of phenoxyfuranone-type SL mimics,termed debranones,has been reported to show potent bioactivities,including reduction of the tiller number on rice,and stimulation of seed germination in the root parasite Striga hermonthica.To exert both activities,two substituents on the phenyl ring of the molecules were important but at least a substituent at the 2-position must be an electron-withdrawing group.However,little is known about the effect of the properties of the substituents at the 2-position on bioactivities.Here,we found that different substituents at the 2-position give different preferences for bioactivities.Halogenated debranones were more effective than the others and SL agonist GR24 for inhibiting rice tiller but far less effective in the induction of S.hermonthica germination.Meanwhile,nitrile and methyl derivatives clearly stimulated the germination of S.hermonthica seeds.Although their IC_(50) values were 100 times higher than that of GR24 in the receptor competitive binding assay,their physiological activities were approximately 1/10 of GR24.These differences could be due to their uptake in plants and/or their physicochemical stability under our experimental conditions.These findings could support the design of more potent and selective SL agonists that could contribute to solving big agricultural issues.
文摘Dear Editor,Most of the plant hormones found in flowering plants contribute to growth regulation in the moss Physcomitrella patens. This moss does not produce gibberellin （GA） （Figure 1A）. An ent-kaurene synthase （PpCPS/KS） and an ent-kaurene oxidase （PpKO） have been identified in P. patens, but in contrast to flowering plants, P. patens has no ent-kaurenoic acid oxidase （KAO） homologs （Hayashi et al., 2010; Miyazaki et al., 2011, Fiqure 1A）.
