"HoneySweet" is a plum variety developed through genetic engineering to be highly resistant to plum pox potyvirus (PPV) the causal agent of sharka disease that threatens stone-fruit industries world-wide, an..."HoneySweet" is a plum variety developed through genetic engineering to be highly resistant to plum pox potyvirus (PPV) the causal agent of sharka disease that threatens stone-fruit industries world-wide, and most specifically in Europe. Field testing for over 15 years in Europe has demonstrated the stable and durable PPV resistance of “HoneySweet”. Resistance is based on gene silencing whereby the inserted gene induces a natural plant defense mechanism against viruses. This resistance has been transferred to seedlings through cross-hybridization as a single locus dominant trait making it useful as a parent for developing new plum varieties for specific growing areas and markets. “HoneySweet” plums are of high quality and compare well to the quality and nutritional value of conventional plums. “HoneySweet” demonstrates the utilization of genetic engineering to provide safe and effective solutions to important agricultural challenges facing growers, and ultimately consumers.展开更多
The C-repeat binding factor(CBF)transcription factor is involved in responses to low temperature and water deficit in many plant species.Overexpression of CBF genes leads to enhanced freezing tolerance and growth inhi...The C-repeat binding factor(CBF)transcription factor is involved in responses to low temperature and water deficit in many plant species.Overexpression of CBF genes leads to enhanced freezing tolerance and growth inhibition in many species.The overexpression of a peach CBF(PpCBF1)gene in a transgenic line of own-rooted apple(Malus×domestica)M.26 rootstock(T166)trees was previously reported to have additional effects on the onset of dormancy and time of spring budbreak.In the current study,the commercial apple cultivar‘Royal Gala’(RG)was grafted onto either non-transgenic M.26 rootstocks(RG/M.26)or transgenic M.26(T166)rootstocks(RG/T166)and field grown for 3 years.No PpCBF1 transcript was detected in the phloem or cambium of RG scions grafted on T166 rootstocks indicating that no graft transmission of transgene mRNA had occurred.In contrast to own-rooted T166 trees,no impact of PpCBF1 overexpression in T166 rootstocks was observed on the onset of dormancy,budbreak or non-acclimated leaf-cold hardiness in RG/T166 trees.Growth,however,as measured by stem caliper,current-year shoot extension and overall height,was reduced in RG/T166 trees compared with RG/M.26 trees.Although flowering was evident in both RG/T166 and RG/M.26 trees in the second season,the number of trees in flower,the number of shoots bearing flowers,and the number of flower clusters per shoot was significantly higher in RG/M.26 trees than RG/T166 trees in both the second and third year after planting.Elevated levels of RGL(DELLA)gene expression were observed in RG/T166 trees and T166 trees,which may play a role in the reduced growth observed in these tree types.A model is presented indicating how CBF overexpression in a rootstock might influence juvenility and flower abundance in a grafted scion.展开更多
Prunus persica(peach)trees carrying the“Pillar”or“Broomy”trait(br)have vertically oriented branches caused by loss-of-function mutations in a gene called TILLER ANGLE CONTROL 1(TAC1).TAC1 encodes a protein in the ...Prunus persica(peach)trees carrying the“Pillar”or“Broomy”trait(br)have vertically oriented branches caused by loss-of-function mutations in a gene called TILLER ANGLE CONTROL 1(TAC1).TAC1 encodes a protein in the IGT gene family that includes LAZY1 and DEEPER ROOTING 1(DRO1),which regulate lateral branch and root orientations,respectively.Here we found that some of the native TAC1 alleles in the hexaploid plum species Prunus domestica,which has a naturally more upright stature,contained a variable length trinucleotide repeat within the same exon 3 region previously found to be disrupted in pillar peach trees.RNAi silencing of TAC1 in plum resulted in trees with severely vertical branch orientations similar to those in pillar peaches but with an even narrower profile.In contrast,PpeTAC1 overexpression in plum led to trees with wider branch angles and more horizontal branch orientations.Pillar peach trees and transgenic plum lines exhibited pleiotropic phenotypes,including differences in trunk and branch diameter,stem growth,and twisting branch phenotypes.Expression profiling of pillar peach trees revealed differential expression of numerous genes associated with biotic and abiotic stress,hormone responses,plastids,reactive oxygen,secondary,and cell wall metabolism.Collectively,the data provide important clues for understanding TAC1 function and show that alteration of TAC1 expression may have broad applicability to agricultural and ornamental tree industries.展开更多
The Dormancy-associated MADS-box(DAM)gene cluster in peach serves as a key regulatory hub on which the seasonal temperatures act and orchestrate dormancy onset and exit,chilling response and floral bud developmental p...The Dormancy-associated MADS-box(DAM)gene cluster in peach serves as a key regulatory hub on which the seasonal temperatures act and orchestrate dormancy onset and exit,chilling response and floral bud developmental pace.Yet,how different temperature regimes interact with and regulate the six linked DAM genes remains unclear.Here,we demonstrate that chilling downregulates DAM1 and DAM3–6 in dormant floral buds with distinct patterns and identify DAM4 as the most abundantly expressed one.We reveal multiple epigenetic events,with tri-methyl histone H3 lysine 27(H3K27me3)induced by chilling specifically in DAM1 and DAM5,a 21-nt sRNA in DAM3 and a ncRNA induced in DAM4.Such induction is inversely correlated with downregulation of their cognate DAMs.We also show that the six DAMs were hypermethylated,associating with the production of 24-nt sRNAs.Hence,the chilling-responsive dynamic of the different epigenetic elements and their interactions likely define distinct expression abundance and downregulation pattern of each DAM.We further show that the expression of the five DAMs remains steadily unchanged or continuously downregulated at the ensuing warm temperature after chilling,and this state of regulation correlates with robust increase of sRNA expression,H3K27me3 and CHH methylation,which is particularly pronounced in DAM4.Such robust increase of repressive epigenetic marks may irreversibly reinforce the chillingimposed repression of DAMs to ensure flower-developmental programming free from any residual DAM inhibition.Taken together,we reveal novel information about genetic and epigenetic regulation of the DAM cluster in peach,which will be of fundamental significance in understanding of the regulatory mechanisms underlying chilling requirement and dormancy release,and of practical application for improvement of plasticity of flower time and bud break in fruit trees to adapt changing climates.展开更多
HoneySweet’plum(Prunus domestica)is resistant to Plum pox potyvirus,through an RNAi-triggered mechanism.Determining the precise nature of the transgene insertion event has been complicated due to the hexaploid genome...HoneySweet’plum(Prunus domestica)is resistant to Plum pox potyvirus,through an RNAi-triggered mechanism.Determining the precise nature of the transgene insertion event has been complicated due to the hexaploid genome of plum.DNA blots previously indicated an unintended hairpin arrangement of the Plum pox potyvirus coat protein gene as well as a multicopy insertion event.To confirm the transgene arrangement of the insertion event,‘HoneySweet’DNA was subjected to whole genome sequencing using Illumina short-read technology.Results indicated two different insertion events,one containing seven partial copies flanked by putative plum DNA sequence and a second with the predicted inverted repeat of the coat protein gene driven by a double 35S promoter on each side,flanked by plum DNA.To determine the locations of the two transgene insertions,a phased plum genome assembly was developed from the commercial plum‘Improved French’.A subset of the scaffolds(2447)that were>10 kb in length and representing,>95%of the genome were annotated and used for alignment against the‘HoneySweet’transgene reads.Four of eight matching scaffolds spanned both insertion sites ranging from 157,704 to 654,883 bp apart,however we were unable to identify which scaffold(s)represented the actual location of the insertion sites due to potential sequence differences between the two plum cultivars.Regardless,there was no evidence of any gene(s)being interrupted as a result of the insertions.Furthermore,RNA-seq data verified that the insertions created no new transcriptional units and no dramatic expression changes of neighboring genes.展开更多
The rice Xa21 gene, which confers resistance to the bacterial pathogen Xanthomonas oryzae pv. oryzae （Xoo）, encodes a receptor-like kinase, Few components involved in transducing the Xa21-mediated defense response h...The rice Xa21 gene, which confers resistance to the bacterial pathogen Xanthomonas oryzae pv. oryzae （Xoo）, encodes a receptor-like kinase, Few components involved in transducing the Xa21-mediated defense response have yet been identified. Here, we report that XA21 binds to a WRKY transcription factor, called OsWRKY62. The OsWRKY62 gene encodes two splice variants （OsWRKY62.1 and OsWRKY62.2）. OsWRKY62.1：smGFP2 and OsWRKY62.2：smGFP2 fusion pro- teins partially localize to the nucleus. Transgenic plants overexpressing OsWRKY62.1 are compromised in basal defense and Xa21-mediated resistance to Xoo. Furthermore, overexpression of OsWRKY62.1 suppresses the activation of defenserelated genes. These results imply that OsWRKY62 functions as a negative regulator of innate immunity in rice, and serves as a critical mediator of both basal and race-specific defense responses.展开更多
基金This work was supported in part by grants from the European Union,FP7-IRSES-Interest n 269292(2011-2014).
文摘"HoneySweet" is a plum variety developed through genetic engineering to be highly resistant to plum pox potyvirus (PPV) the causal agent of sharka disease that threatens stone-fruit industries world-wide, and most specifically in Europe. Field testing for over 15 years in Europe has demonstrated the stable and durable PPV resistance of “HoneySweet”. Resistance is based on gene silencing whereby the inserted gene induces a natural plant defense mechanism against viruses. This resistance has been transferred to seedlings through cross-hybridization as a single locus dominant trait making it useful as a parent for developing new plum varieties for specific growing areas and markets. “HoneySweet” plums are of high quality and compare well to the quality and nutritional value of conventional plums. “HoneySweet” demonstrates the utilization of genetic engineering to provide safe and effective solutions to important agricultural challenges facing growers, and ultimately consumers.
文摘The C-repeat binding factor(CBF)transcription factor is involved in responses to low temperature and water deficit in many plant species.Overexpression of CBF genes leads to enhanced freezing tolerance and growth inhibition in many species.The overexpression of a peach CBF(PpCBF1)gene in a transgenic line of own-rooted apple(Malus×domestica)M.26 rootstock(T166)trees was previously reported to have additional effects on the onset of dormancy and time of spring budbreak.In the current study,the commercial apple cultivar‘Royal Gala’(RG)was grafted onto either non-transgenic M.26 rootstocks(RG/M.26)or transgenic M.26(T166)rootstocks(RG/T166)and field grown for 3 years.No PpCBF1 transcript was detected in the phloem or cambium of RG scions grafted on T166 rootstocks indicating that no graft transmission of transgene mRNA had occurred.In contrast to own-rooted T166 trees,no impact of PpCBF1 overexpression in T166 rootstocks was observed on the onset of dormancy,budbreak or non-acclimated leaf-cold hardiness in RG/T166 trees.Growth,however,as measured by stem caliper,current-year shoot extension and overall height,was reduced in RG/T166 trees compared with RG/M.26 trees.Although flowering was evident in both RG/T166 and RG/M.26 trees in the second season,the number of trees in flower,the number of shoots bearing flowers,and the number of flower clusters per shoot was significantly higher in RG/M.26 trees than RG/T166 trees in both the second and third year after planting.Elevated levels of RGL(DELLA)gene expression were observed in RG/T166 trees and T166 trees,which may play a role in the reduced growth observed in these tree types.A model is presented indicating how CBF overexpression in a rootstock might influence juvenility and flower abundance in a grafted scion.
基金This work was supported by Agriculture and Food Research Initiative Competitive grant 10891264 from the USDA National Institute of Food and Agriculture and by the National Science Foundation grant number 1339211.
文摘Prunus persica(peach)trees carrying the“Pillar”or“Broomy”trait(br)have vertically oriented branches caused by loss-of-function mutations in a gene called TILLER ANGLE CONTROL 1(TAC1).TAC1 encodes a protein in the IGT gene family that includes LAZY1 and DEEPER ROOTING 1(DRO1),which regulate lateral branch and root orientations,respectively.Here we found that some of the native TAC1 alleles in the hexaploid plum species Prunus domestica,which has a naturally more upright stature,contained a variable length trinucleotide repeat within the same exon 3 region previously found to be disrupted in pillar peach trees.RNAi silencing of TAC1 in plum resulted in trees with severely vertical branch orientations similar to those in pillar peaches but with an even narrower profile.In contrast,PpeTAC1 overexpression in plum led to trees with wider branch angles and more horizontal branch orientations.Pillar peach trees and transgenic plum lines exhibited pleiotropic phenotypes,including differences in trunk and branch diameter,stem growth,and twisting branch phenotypes.Expression profiling of pillar peach trees revealed differential expression of numerous genes associated with biotic and abiotic stress,hormone responses,plastids,reactive oxygen,secondary,and cell wall metabolism.Collectively,the data provide important clues for understanding TAC1 function and show that alteration of TAC1 expression may have broad applicability to agricultural and ornamental tree industries.
基金funded by the ARS-INHouse fund,USDA-NIFA grant(3200000379-16-182)the National Natural Science Foundation of China(31772371)and AoE grant(AoE/M-403/16).
文摘The Dormancy-associated MADS-box(DAM)gene cluster in peach serves as a key regulatory hub on which the seasonal temperatures act and orchestrate dormancy onset and exit,chilling response and floral bud developmental pace.Yet,how different temperature regimes interact with and regulate the six linked DAM genes remains unclear.Here,we demonstrate that chilling downregulates DAM1 and DAM3–6 in dormant floral buds with distinct patterns and identify DAM4 as the most abundantly expressed one.We reveal multiple epigenetic events,with tri-methyl histone H3 lysine 27(H3K27me3)induced by chilling specifically in DAM1 and DAM5,a 21-nt sRNA in DAM3 and a ncRNA induced in DAM4.Such induction is inversely correlated with downregulation of their cognate DAMs.We also show that the six DAMs were hypermethylated,associating with the production of 24-nt sRNAs.Hence,the chilling-responsive dynamic of the different epigenetic elements and their interactions likely define distinct expression abundance and downregulation pattern of each DAM.We further show that the expression of the five DAMs remains steadily unchanged or continuously downregulated at the ensuing warm temperature after chilling,and this state of regulation correlates with robust increase of sRNA expression,H3K27me3 and CHH methylation,which is particularly pronounced in DAM4.Such robust increase of repressive epigenetic marks may irreversibly reinforce the chillingimposed repression of DAMs to ensure flower-developmental programming free from any residual DAM inhibition.Taken together,we reveal novel information about genetic and epigenetic regulation of the DAM cluster in peach,which will be of fundamental significance in understanding of the regulatory mechanisms underlying chilling requirement and dormancy release,and of practical application for improvement of plasticity of flower time and bud break in fruit trees to adapt changing climates.
文摘HoneySweet’plum(Prunus domestica)is resistant to Plum pox potyvirus,through an RNAi-triggered mechanism.Determining the precise nature of the transgene insertion event has been complicated due to the hexaploid genome of plum.DNA blots previously indicated an unintended hairpin arrangement of the Plum pox potyvirus coat protein gene as well as a multicopy insertion event.To confirm the transgene arrangement of the insertion event,‘HoneySweet’DNA was subjected to whole genome sequencing using Illumina short-read technology.Results indicated two different insertion events,one containing seven partial copies flanked by putative plum DNA sequence and a second with the predicted inverted repeat of the coat protein gene driven by a double 35S promoter on each side,flanked by plum DNA.To determine the locations of the two transgene insertions,a phased plum genome assembly was developed from the commercial plum‘Improved French’.A subset of the scaffolds(2447)that were>10 kb in length and representing,>95%of the genome were annotated and used for alignment against the‘HoneySweet’transgene reads.Four of eight matching scaffolds spanned both insertion sites ranging from 157,704 to 654,883 bp apart,however we were unable to identify which scaffold(s)represented the actual location of the insertion sites due to potential sequence differences between the two plum cultivars.Regardless,there was no evidence of any gene(s)being interrupted as a result of the insertions.Furthermore,RNA-seq data verified that the insertions created no new transcriptional units and no dramatic expression changes of neighboring genes.
文摘The rice Xa21 gene, which confers resistance to the bacterial pathogen Xanthomonas oryzae pv. oryzae （Xoo）, encodes a receptor-like kinase, Few components involved in transducing the Xa21-mediated defense response have yet been identified. Here, we report that XA21 binds to a WRKY transcription factor, called OsWRKY62. The OsWRKY62 gene encodes two splice variants （OsWRKY62.1 and OsWRKY62.2）. OsWRKY62.1：smGFP2 and OsWRKY62.2：smGFP2 fusion pro- teins partially localize to the nucleus. Transgenic plants overexpressing OsWRKY62.1 are compromised in basal defense and Xa21-mediated resistance to Xoo. Furthermore, overexpression of OsWRKY62.1 suppresses the activation of defenserelated genes. These results imply that OsWRKY62 functions as a negative regulator of innate immunity in rice, and serves as a critical mediator of both basal and race-specific defense responses.
