Indole-3-acetic acid （IAA）, a major plant auxin, is produced in both tryptophan-dependent and tryptophan-independent pathways. A major pathway in Arabidopsis thaliana generates IAA in two reactions from tryptophan. ...Indole-3-acetic acid （IAA）, a major plant auxin, is produced in both tryptophan-dependent and tryptophan-independent pathways. A major pathway in Arabidopsis thaliana generates IAA in two reactions from tryptophan. Step one converts tryptophan to indole-3-pyruvic acid （IPA） by tryptophan aminotransferases followed by a rate-limiting step converting IPA to IAA catalyzed by YUCCA proteins. We identified eight putative StYUC （Solanum tuberosum YUCCA） genes whose deduced amino acid sequences share 50%-70% identity with those of Arabidopsis YUCCA proteins. All include canonical, conserved YUCCA sequences： FATGY motif, FMO signature sequence, and FAD-binding and NADP-binding sequences. In addition, five genes were found with -50% amino acid sequence identity to Arabidopsis trypto-phan aminotransferases. Transgenic potato （Solanum tuberosum cv. Jowon） constitutively overexpressing Arabidopsis AtYUC6 displayed high-auxin phenotypes such as narrow downward-curled leaves, increased height, erect stature, and longevity. Transgenic potato plants overexpressing AtYUC6 showed enhanced drought tolerance based on reduced water loss. The phenotype was correlated with reduced levels of reactive oxygen species in leaves. The results suggest a func-tional YUCCA pathway of auxin biosynthesis in potato that may be exploited to alter plant responses to the environment.展开更多
Auxin has been regarded as the main signal molecule coordinating the growth and ripening of fruits in strawberry, the reference genomic system for Rosaceae. The mechanisms regulating auxin biosynthesis in strawberry a...Auxin has been regarded as the main signal molecule coordinating the growth and ripening of fruits in strawberry, the reference genomic system for Rosaceae. The mechanisms regulating auxin biosynthesis in strawberry are largely elusive. Recently, we demonstrated that two YUCCA genes are involved in flower and fruit development in cultivated strawberry. Here, we show that the woodland strawberry （Fragaria vesca L.） genome harbors nine loci for YUCCA genes and eight of them encode functional proteins. Transcription pattern in different plant organs was different for all eight FvYUCs. Functionality of the FvYUC6 gene was studied in transgenic strawberry over- expressing FvYUC6, which showed typical high-auxin pheno- types. Overexpression of FvYUC6 also delayed flowering and led to complete male sterility in F. vesta. Additionally, specific repression of FvYUC6 expression by RNA interference signifi- cantly inhibited vegetative growth and reduced plant fertility. The development of leaves, roots, flowers, and fruits was greatly affected in FvYUC6-repressed plants. Expression of a subset of auxin-responsive genes was well correlated with the changes of FvYUC6 transcript levels and free indole-3-acetic acid levels in transgenic strawberry. These observations are consistent with an important role of FvYUC6 in auxin synthesis, and support a main role of the gene product in vegetative and reproductive development in woodland strawberry.展开更多
Auxin plays important roles in various aspects of plant growth and development （Zhao, 2010）. In Arabidopsis, a number of YUCCA （YUC） genes, which are involved in auxin biosyn- thesis, have been identified （Zhao e...Auxin plays important roles in various aspects of plant growth and development （Zhao, 2010）. In Arabidopsis, a number of YUCCA （YUC） genes, which are involved in auxin biosyn- thesis, have been identified （Zhao et al., 2001; Woodward et al., 2005; Cheng et al., 2006, 2007; Kim et al., 2007; Chen et al., 2014）. YUC genes encode flavin monooxygenases （FMOs） that convert indole-3-pyruvate （IPA） to indole-3-acetic acid （IAA） （Zhao, 2012）. The Arabidopsis YUC family is comprised of 11 members （Zhao et al., 2001;展开更多
De novo root regeneration(DNRR) has wide applications in agriculture such as those related to cutting technology. Detached Arabidopsis thaliana leaf explants can regenerate adventitious roots without added hormones. T...De novo root regeneration(DNRR) has wide applications in agriculture such as those related to cutting technology. Detached Arabidopsis thaliana leaf explants can regenerate adventitious roots without added hormones. The regenerative ability is highly dependent on the developmental status of the leaf. An immature leaf has a higher regenerative ability, while a mature leaf is difficult to regenerate. Using RNASeq analysis, we showed that the expression levels of many genes, including those in the auxin network,changed during leaf maturation. Particularly, the expression levels of many YUCCA(YUC) genes in the auxin biosynthesis pathway are responsive to leaf maturation. Overexpression of YUC1 in the yuc-1 D dominant mutant rescued the rooting defects caused by leaf maturation. In addition, YUC4 expression levels were also affected by circadian rhythms. The regenerative ability was reduced in both immature and mature mutant leaf explants from the new wuschel-related homeobox 11-3(wox11-3) and wox12-3 mutant alleles created by the CRISPR/Cas9 method. Overall, the transcriptome and genetic data, together with the auxin concentration analysis, indicate that the ability to upregulate auxin levels upon detachment may be reduced during leaf maturation. Thus, multiple developmental and environmental signals may converge to control auxin accumulation, which affects the efficiency of the WOX11/12-mediated DNRR from leaf explants.展开更多
Brassinosteroids （BRs） are important plant hormones that act synergistically with auxin to regulate a variety of plant developmental and physiological processes. In the past decade, genetic and biochemical studies h...Brassinosteroids （BRs） are important plant hormones that act synergistically with auxin to regulate a variety of plant developmental and physiological processes. In the past decade, genetic and biochemical studies have revealed a linear signaling pathway that relies on protein phosphorylation to transmit the BR signal into the nucleus, altering ex- pression of hundreds of genes to promote plant growth. We conducted an activation-tagging based suppressor screen to look for Arabidopsis genes that, when overexpressed by inserted 35S enhancer elements, could suppress the dwarf phe- notype of a weak BR receptor mutant bril-301. This screen identified a total of six dominant activation-tagged bril sup- pressors （atbs-Ds）. Using a plasmid rescue approach, we discovered that the bril-301 suppression effect in four atbs-D mutants （atbs3-D to atbs6-D） was caused by overexpression of a YUCCA gene thought to be involved in tryptophan- dependent auxin biosynthesis. Interestingly, the three activation-tagged YUCCA genes belong to the YUCCA IIA subfamily that includes two other members out of 11 known Arabidopsis YUCCA genes. In addition, our molecular studies revealed a T-DNA insertion near a basic helix-loop-helix gene in atbsl-D and a T-DNA insertion in a region carrying a BR biosynthetic gene in atbs2-D. Further studies of these atbs-D mutants could lead to better understanding of the BR signaling process and the BR-auxin interaction.展开更多
The genus Yucca comprising of several species is dominant across the chaparrals,canyons and deserts of American South West and Mexico.This genus has long been a source of sustenance and drugs for the Native Americans....The genus Yucca comprising of several species is dominant across the chaparrals,canyons and deserts of American South West and Mexico.This genus has long been a source of sustenance and drugs for the Native Americans.In the wake of revived interest in drug discovery from plant sources,this genus has been investigated and startling nutritive and therapeutic capacities have come forth.Apart from the functional food potential,antioxidant,antiinflammation,antiarthritic,anticancer,antidiabetic,antimicrobial,and hypocholesterolaemic properties have also been revealed.Steroidal saponins,resveratrol and yuccaols have been identified to be the active principles with myriad biological actions.To stimulate further research on this genus of multiple food and pharmaceutical uses,this updated review has been prepared with references extracted from MEDLINE database.展开更多
In a completely randomized block design experiment, 16 ruminally cannulated sheep （40 ±2.1 kg）fed a 50% concentrate： 50% forage diet （DM basis） were given intraruminal doses of powdered Yucca schidigera extr...In a completely randomized block design experiment, 16 ruminally cannulated sheep （40 ±2.1 kg）fed a 50% concentrate： 50% forage diet （DM basis） were given intraruminal doses of powdered Yucca schidigera extract （YSE）. Doses of 0 （control）, 100, 200, or 300 mg kg^-1 diet were given at 8 p.m. and 4 a.m. On 15, 16, and 17 d of the experimental period, ruminal contents were sampled 0, 2, 4, 6, and 8 h after dosing, and blood samples were collected at the end of the experiment （18th and 19th d）. Acidity was not affected （P〉0.05） by the addition of YSE. Compared with the control, ruminal propionate concentration was increased by 29.4 and 29.8% （P〉 0.05） and the acetic acid concentration was decreased by 15.1 and 19.8% （P〉0.05） at 4 and 6 h after YSE （300 mg kg^-1） dosing, respectively. Ruminal ammonia concentration in the first 2 h after feeding was higher （P〈0.05） in the sheep that did not receive YSE （increased by 17.57 mg 100 mL^-1） than in those that received 200 mg kg^-1（increased by 6.77 mg 100 mL^-1） or 300 mg kg^-1 （increased by 6.50 mg 100 mL^-1） YSE. Protozoan populations in the rumen were lower （P〈0.05） in the animals that received 300 mg kg^-1 of YSE compared with the control. All serum parameters of the four groups were in the normal range and were similar among the treatment groups （P 〉 0.05）, after being fed for 19 d with different doses of YSE. The effect of YSE on ruminal ammonia concentration likely resulted from a decreased concentration of protozoan populations and, presumably, from ammonia binding by YSE.展开更多
Prescribed fire produced a landscape with two types of severely burned patches: charred shrub patches and charred patches with tree trunks at the center. Soil nematodes were more abundant in burned and unburned junipe...Prescribed fire produced a landscape with two types of severely burned patches: charred shrub patches and charred patches with tree trunks at the center. Soil nematodes were more abundant in burned and unburned juniper (Juniperus monosperma) tree patches than in yucca-shrub patches. There were no differences in nematode abundance between burned and unburned patches during the late spring and summer samples. Nematode abundance was significantly (p < 0.05) higher in unburned patches than in burned patches in the early spring samples, reflecting large differences in soil moisture between unburned and burned patches. There were no differences in soil nematode abundance between burned and unburned patches at oneyear post-burn and three-year post-burn sites. When all samples were pooled, taxonomic diversity, ecological indices, and abundance of trophic groups (bacteria-feeders, fungi-feeders, and omnivore-predators) were higher in unburned than burned patches. These results suggest that the long-term (up to three years post-burn) effects of fire on soil nematodes are indirect, i.e., by loss of tree canopies, litter accumulation, and shrub foliage, which affects soil temperatures and water redistribution.展开更多
文摘Indole-3-acetic acid （IAA）, a major plant auxin, is produced in both tryptophan-dependent and tryptophan-independent pathways. A major pathway in Arabidopsis thaliana generates IAA in two reactions from tryptophan. Step one converts tryptophan to indole-3-pyruvic acid （IPA） by tryptophan aminotransferases followed by a rate-limiting step converting IPA to IAA catalyzed by YUCCA proteins. We identified eight putative StYUC （Solanum tuberosum YUCCA） genes whose deduced amino acid sequences share 50%-70% identity with those of Arabidopsis YUCCA proteins. All include canonical, conserved YUCCA sequences： FATGY motif, FMO signature sequence, and FAD-binding and NADP-binding sequences. In addition, five genes were found with -50% amino acid sequence identity to Arabidopsis trypto-phan aminotransferases. Transgenic potato （Solanum tuberosum cv. Jowon） constitutively overexpressing Arabidopsis AtYUC6 displayed high-auxin phenotypes such as narrow downward-curled leaves, increased height, erect stature, and longevity. Transgenic potato plants overexpressing AtYUC6 showed enhanced drought tolerance based on reduced water loss. The phenotype was correlated with reduced levels of reactive oxygen species in leaves. The results suggest a func-tional YUCCA pathway of auxin biosynthesis in potato that may be exploited to alter plant responses to the environment.
基金the Science and Technology Commission of Shanghai Municipality (Shanghai Rising-Star Program (09QA1405300) to K. D., Key Program (12391901400) to Q. H. G.)Shanghai Academy of Agricultural Sciences (S & T Development Program (2012(13)) to K. D.). V. V. was funded by MICINN (Spain), grant no. BIO2010-15630
文摘Auxin has been regarded as the main signal molecule coordinating the growth and ripening of fruits in strawberry, the reference genomic system for Rosaceae. The mechanisms regulating auxin biosynthesis in strawberry are largely elusive. Recently, we demonstrated that two YUCCA genes are involved in flower and fruit development in cultivated strawberry. Here, we show that the woodland strawberry （Fragaria vesca L.） genome harbors nine loci for YUCCA genes and eight of them encode functional proteins. Transcription pattern in different plant organs was different for all eight FvYUCs. Functionality of the FvYUC6 gene was studied in transgenic strawberry over- expressing FvYUC6, which showed typical high-auxin pheno- types. Overexpression of FvYUC6 also delayed flowering and led to complete male sterility in F. vesta. Additionally, specific repression of FvYUC6 expression by RNA interference signifi- cantly inhibited vegetative growth and reduced plant fertility. The development of leaves, roots, flowers, and fruits was greatly affected in FvYUC6-repressed plants. Expression of a subset of auxin-responsive genes was well correlated with the changes of FvYUC6 transcript levels and free indole-3-acetic acid levels in transgenic strawberry. These observations are consistent with an important role of FvYUC6 in auxin synthesis, and support a main role of the gene product in vegetative and reproductive development in woodland strawberry.
基金financially supported by the grant from the National Plant Transgenic Program(No.2013ZX08003-003)from Ministry of Agriculture of the People’s Republic of China
文摘Auxin plays important roles in various aspects of plant growth and development （Zhao, 2010）. In Arabidopsis, a number of YUCCA （YUC） genes, which are involved in auxin biosyn- thesis, have been identified （Zhao et al., 2001; Woodward et al., 2005; Cheng et al., 2006, 2007; Kim et al., 2007; Chen et al., 2014）. YUC genes encode flavin monooxygenases （FMOs） that convert indole-3-pyruvate （IPA） to indole-3-acetic acid （IAA） （Zhao, 2012）. The Arabidopsis YUC family is comprised of 11 members （Zhao et al., 2001;
基金supported by grants from the National Natural Science Foundation of China (31630007, 31770399 and 21375066)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB27030103)+1 种基金the Key Research Program of CAS (QYZDB-SSWSMC010)the National Key Laboratory of Plant Molecular Genetics
文摘De novo root regeneration(DNRR) has wide applications in agriculture such as those related to cutting technology. Detached Arabidopsis thaliana leaf explants can regenerate adventitious roots without added hormones. The regenerative ability is highly dependent on the developmental status of the leaf. An immature leaf has a higher regenerative ability, while a mature leaf is difficult to regenerate. Using RNASeq analysis, we showed that the expression levels of many genes, including those in the auxin network,changed during leaf maturation. Particularly, the expression levels of many YUCCA(YUC) genes in the auxin biosynthesis pathway are responsive to leaf maturation. Overexpression of YUC1 in the yuc-1 D dominant mutant rescued the rooting defects caused by leaf maturation. In addition, YUC4 expression levels were also affected by circadian rhythms. The regenerative ability was reduced in both immature and mature mutant leaf explants from the new wuschel-related homeobox 11-3(wox11-3) and wox12-3 mutant alleles created by the CRISPR/Cas9 method. Overall, the transcriptome and genetic data, together with the auxin concentration analysis, indicate that the ability to upregulate auxin levels upon detachment may be reduced during leaf maturation. Thus, multiple developmental and environmental signals may converge to control auxin accumulation, which affects the efficiency of the WOX11/12-mediated DNRR from leaf explants.
文摘Brassinosteroids （BRs） are important plant hormones that act synergistically with auxin to regulate a variety of plant developmental and physiological processes. In the past decade, genetic and biochemical studies have revealed a linear signaling pathway that relies on protein phosphorylation to transmit the BR signal into the nucleus, altering ex- pression of hundreds of genes to promote plant growth. We conducted an activation-tagging based suppressor screen to look for Arabidopsis genes that, when overexpressed by inserted 35S enhancer elements, could suppress the dwarf phe- notype of a weak BR receptor mutant bril-301. This screen identified a total of six dominant activation-tagged bril sup- pressors （atbs-Ds）. Using a plasmid rescue approach, we discovered that the bril-301 suppression effect in four atbs-D mutants （atbs3-D to atbs6-D） was caused by overexpression of a YUCCA gene thought to be involved in tryptophan- dependent auxin biosynthesis. Interestingly, the three activation-tagged YUCCA genes belong to the YUCCA IIA subfamily that includes two other members out of 11 known Arabidopsis YUCCA genes. In addition, our molecular studies revealed a T-DNA insertion near a basic helix-loop-helix gene in atbsl-D and a T-DNA insertion in a region carrying a BR biosynthetic gene in atbs2-D. Further studies of these atbs-D mutants could lead to better understanding of the BR signaling process and the BR-auxin interaction.
文摘The genus Yucca comprising of several species is dominant across the chaparrals,canyons and deserts of American South West and Mexico.This genus has long been a source of sustenance and drugs for the Native Americans.In the wake of revived interest in drug discovery from plant sources,this genus has been investigated and startling nutritive and therapeutic capacities have come forth.Apart from the functional food potential,antioxidant,antiinflammation,antiarthritic,anticancer,antidiabetic,antimicrobial,and hypocholesterolaemic properties have also been revealed.Steroidal saponins,resveratrol and yuccaols have been identified to be the active principles with myriad biological actions.To stimulate further research on this genus of multiple food and pharmaceutical uses,this updated review has been prepared with references extracted from MEDLINE database.
文摘In a completely randomized block design experiment, 16 ruminally cannulated sheep （40 ±2.1 kg）fed a 50% concentrate： 50% forage diet （DM basis） were given intraruminal doses of powdered Yucca schidigera extract （YSE）. Doses of 0 （control）, 100, 200, or 300 mg kg^-1 diet were given at 8 p.m. and 4 a.m. On 15, 16, and 17 d of the experimental period, ruminal contents were sampled 0, 2, 4, 6, and 8 h after dosing, and blood samples were collected at the end of the experiment （18th and 19th d）. Acidity was not affected （P〉0.05） by the addition of YSE. Compared with the control, ruminal propionate concentration was increased by 29.4 and 29.8% （P〉 0.05） and the acetic acid concentration was decreased by 15.1 and 19.8% （P〉0.05） at 4 and 6 h after YSE （300 mg kg^-1） dosing, respectively. Ruminal ammonia concentration in the first 2 h after feeding was higher （P〈0.05） in the sheep that did not receive YSE （increased by 17.57 mg 100 mL^-1） than in those that received 200 mg kg^-1（increased by 6.77 mg 100 mL^-1） or 300 mg kg^-1 （increased by 6.50 mg 100 mL^-1） YSE. Protozoan populations in the rumen were lower （P〈0.05） in the animals that received 300 mg kg^-1 of YSE compared with the control. All serum parameters of the four groups were in the normal range and were similar among the treatment groups （P 〉 0.05）, after being fed for 19 d with different doses of YSE. The effect of YSE on ruminal ammonia concentration likely resulted from a decreased concentration of protozoan populations and, presumably, from ammonia binding by YSE.
文摘Prescribed fire produced a landscape with two types of severely burned patches: charred shrub patches and charred patches with tree trunks at the center. Soil nematodes were more abundant in burned and unburned juniper (Juniperus monosperma) tree patches than in yucca-shrub patches. There were no differences in nematode abundance between burned and unburned patches during the late spring and summer samples. Nematode abundance was significantly (p < 0.05) higher in unburned patches than in burned patches in the early spring samples, reflecting large differences in soil moisture between unburned and burned patches. There were no differences in soil nematode abundance between burned and unburned patches at oneyear post-burn and three-year post-burn sites. When all samples were pooled, taxonomic diversity, ecological indices, and abundance of trophic groups (bacteria-feeders, fungi-feeders, and omnivore-predators) were higher in unburned than burned patches. These results suggest that the long-term (up to three years post-burn) effects of fire on soil nematodes are indirect, i.e., by loss of tree canopies, litter accumulation, and shrub foliage, which affects soil temperatures and water redistribution.
