Roses,which have been cultivated for at least 5000 years,are one of the most important ornamental crops in the world.Because of the interspecific nature and high heterozygosity in commercial roses,the genetic resource...Roses,which have been cultivated for at least 5000 years,are one of the most important ornamental crops in the world.Because of the interspecific nature and high heterozygosity in commercial roses,the genetic resources available for rose are limited.To effectively identify markers associated with QTL controlling important traits,such as disease resistance,abundant markers along the genome and careful phenotyping are required.Utilizing genotyping by sequencing technology and the strawberry genome(Fragaria vesca v2.0.a1)as a reference,we generated thousands of informative single nucleotide polymorphism(SNP)markers.These SNPs along with known bridge simple sequence repeat(SSR)markers allowed us to create the first high-density integrated consensus map for diploid roses.Individual maps were first created for populations J06-20-14-3דLittle Chief”(J14-3×LC),J06-20-14-3דVineyard Song”(J14-3×VS)and“Old Blush”דRed Fairy”(OB×RF)and these maps were linked with 824 SNPs and 13 SSR bridge markers.The anchor SSR markers were used to determine the numbering of the rose linkage groups.The diploid consensus map has seven linkage groups(LGs),a total length of 892.2 cM,and an average distance of 0.25 cM between 3527 markers.By combining three individual populations,the marker density and the reliability of the marker order in the consensus map was improved over a single population map.Extensive synteny between the strawberry and diploid rose genomes was observed.This consensus map will serve as the tool for the discovery of marker–trait associations in rose breeding using pedigree-based analysis.The high level of conservation observed between the strawberry and rose genomes will help further comparative studies within the Rosaceae family and may aid in the identification of candidate genes within QTL regions.展开更多
In this report we have evaluated metabolite and RNA profiling technologies to begin to understand the natural variation in these biomolecules found in commercial-quality, conventional (non-GM) maize hybrids. Our analy...In this report we have evaluated metabolite and RNA profiling technologies to begin to understand the natural variation in these biomolecules found in commercial-quality, conventional (non-GM) maize hybrids. Our analyses focus on mature grain, the article of commerce that is most typically subjected to the rigorous studies involved in the comparative safety assessment of GM products. We have used a population of conventionally-bred maize hybrids that derive from closely related inbred parents grown under standard field conditions across geographically similar locations. This study highlights the large amount of natural variation in metabolites and transcripts across conventional maize germplasm grown under normal field conditions, and underscores the critical need for further extensive studies before these technologies can be seriously considered for utility in the comparative safety assessment of GM crops.展开更多
Over the last two decades, transgenic plants have moved from being solely laboratory vehicles for basic research work to providing new varieties grown on large areas throughout the world. A number of
To develop better varieties for farmers and to increase overall agricultural productivity, Monsanto Company has continued to lead innovations in plant biotech, breeding and molecular breeding. In Molecular breeding, non-
Informative,portable,and efficient DNA markers have the potential to accelerate genetic gain in cotton breeding.Discovery and widespread application of DNA markers to cotton has
Nitrogen fertilization is one of the greatest challenges associated with the production of biofuel from corn grain. The objective of this research was to determine the effect of N fertilization on the content and yiel...Nitrogen fertilization is one of the greatest challenges associated with the production of biofuel from corn grain. The objective of this research was to determine the effect of N fertilization on the content and yield of oil, protein, and starch in corn grain. The project was done in Southeast Missouri （USA）, from 2007 to 2009 in a silt loam soil. Corn grain contains 3.8-4.2% oil, 6.7%-8.9% protein, 68.0%-70.4% extractable starch, and 76.0%-77.7% total starch. The total starch yield ranged from 2.8 to 7.8 mg.ha1 whereas the extractable starch varied between 2.5 to 7.1 mg-ha1. As the N rate went up, the oil and starch content of the grain decreased, whereas the protein content and the protein, starch, and oil yields increased, reaching their maximum at the N rate corresponding to 179.0 kg N.ha~. The potential ethanol yield varied between 616.2 and 7,035.1 L-ha1 depending on the method of conversion of the starch into ethanol, the year and the N rate （P 〈 0.0001）. The negative correlation between N fertilization rate and starch content suggested that when farmers add too much N to their soil to increase grain yield, they reduce the starch content in those grains, and consequently the conversion into bioethanol. Therefore, for biofuel production to be beneficial for both farmers and the power plant owners, an agreement needs to be made with regard to the use of fertilizers.展开更多
Reactive oxygen species （ROS） play an important role in root responses to potassium deprivation by regulating the expression of the high-affinity K＋ transporter gene AtHAK5 and other genes. Activation-tagged lines ...Reactive oxygen species （ROS） play an important role in root responses to potassium deprivation by regulating the expression of the high-affinity K＋ transporter gene AtHAK5 and other genes. Activation-tagged lines of Arabidopsis plants containing the AtHAK5 promoter driving luciferase were screened for bioluminescence under potassium- sufficient conditions. A member of the type Ill peroxidase family, RCI3, was isolated and when it was overexpressed by the activation tag, this led to the enhanced expression of luciferase and the endogenous AtHAKS. RCI3 was found to be up- regulated upon potassium deprivation. Plants overexpressing RCI3 （RCI3-ox） showed more ROS production and AtHAK5 expression whereas the ROS production and AtHAK5 expression were reduced in rci3-1 under K＋-deprived conditions. These results suggested that RCI3 is involved in the production of ROS under potassium deprivation and that RCI3- mediated ROS production affects the regulation of AtHAK5 expression. This peroxidase appears to be another component of the low-potassium signal transduction pathway in Arabidopsis roots.展开更多
Plants respond to low-nutrient conditions through metabolic and morphology changes that increase their ability to survive and grow. The transcription factor RAP2.11 was identified as a component in the response to low...Plants respond to low-nutrient conditions through metabolic and morphology changes that increase their ability to survive and grow. The transcription factor RAP2.11 was identified as a component in the response to low potassium through regulation of the high-affinity K＋ uptake transporter AtHAK5 and other components of the low- potassium signal transduction pathway. RAP2.11 was identified through the activation tagging of Arabidopsis lines that contained a luciferase marker driven by the AtHAK5 promoter that is normally only induced by low potassium. This factor bound to a GCC-box of the AtHAK5 promoter in vitro and in vivo. Transcript profiling revealed that a large number of genes were up-regulated in roots by RAP2.11 overexpression. Many regulated genes were identified to be in functional cate- gories that are important in Iow-K＋ signaling. These categories included ethylene signaling, reactive oxygen species pro- duction, and calcium signaling. Promoter regions of the up-regulated genes were enriched in the GCCGGC motif also contained in the AtHAK5 promoter. These results suggest that RAP2.11 regulates AtHAK5 expression under Iow-K＋ con- ditions and also contributes to a coordinated response to low-potassium conditions through the regulation of other genes in the Iow-K＋ signaling cascade.展开更多
The sugarcane borer, Diatraea saccharalis （E）, is a major maize borer pest and a target of transgenic maize expressing Bacillus thuringiensis （Bt） proteins in South America and the mid-southern region of the Unite...The sugarcane borer, Diatraea saccharalis （E）, is a major maize borer pest and a target of transgenic maize expressing Bacillus thuringiensis （Bt） proteins in South America and the mid-southern region of the United States. Evolution of resistance in target pest populations is a great threat to the long-term efficacy of Bt crops. In this study, we compared the genetic basis of resistance to CrylAb protein in 3 resistant colonies of sugarcane borer established from field populations in Louisiana, USA. Responses of larvae to the CrylAb protein for the parental and 10 other cross colonies were assayed in a diet-incorporated bioassay. All 3 resistant colonies were highly resistant to the CrylAb protein with a resistance ratio of 〉 5 5 5.6 fold. No maternal effect or sex linkage was evident for the resistance in the 3 colonies; and the resistance was functionally nonrecessive at the CrylAb concentrations of 〈 3.16 μg/g, but it became recessive at 〉10μg/g. In an interstrain complementation test for allelism, the Fl progeny from crosses between any 2 of the 3 resistant colonies exhibited the similar resistance levels as their parental colonies, indicating that the 3 colonies most likely shared a locus of CrylAb resistance. Results generated from this study should provide useful information in developing effective strategies for managing Bt resistance in the insect.展开更多
Western corn rootworm （WCR, Diabrotica virgifera virgifera LeConte） is highly sensitive to orally delivered double-stranded RNA （dsRNA）. RNAi in WCR is systemic and spreads throughout the insect body. This raises ...Western corn rootworm （WCR, Diabrotica virgifera virgifera LeConte） is highly sensitive to orally delivered double-stranded RNA （dsRNA）. RNAi in WCR is systemic and spreads throughout the insect body. This raises the question whether transitive RNAi is a mechanism that functions in WCR to amplify the RNAi response via production of secondary siRNA. Secondary siRNA production is achieved through RNA-dependent RNA polymerase （RdRP） activity in other eukaryotic organisms, but RdRP has not been identified in WCR and any other insects. This study visualized the spread of the RNAi- mediated knockdown of Dr v-ATPase C mRNA throughout the WCR gut and other tissues using high-sensitivity branched DNA in situ hybridization. Furthermore, we did not detect either secondary siRNA production or transitive RNAi in WCR through siRNA sequence profile analysis. Nucleotide mismatched sequences introduced into either the sense or antisense strand of v-ATPase C dsRNAs were maintained in siRNAs derived from WCR fed with the mismatched dsRNAs in a strand specific manner. The distribution of all siRNAs was restricted to within the original target sequence regions, which may indicate the lack of new dsRNA synthesis leading to production of secondary siRNA. Thus, the systemic spread of RNAi in WCR may be derived from the original dsRNA molecules taken up from the gut lumen. These results indicate that the initial dsRNA dose is important for a lethal systemic RNAi response in WCR and have implications in developing effective dsRNA traits to control WCR and in resistance management to prolong the durability of RNAi trait technology.展开更多
Dear Editor, Understanding how Kranz anatomy develops in C4 plants is a critical part of the current worldwide effort to transfer C4 photosynthesis into C3 plants, including rice. Recently, it was proposed that the K...Dear Editor, Understanding how Kranz anatomy develops in C4 plants is a critical part of the current worldwide effort to transfer C4 photosynthesis into C3 plants, including rice. Recently, it was proposed that the Kranz architecture that supports C4 photosynthesis in maize leaves is an extension of the endodermal program, which is active in roots, stems, and petioles, and is ubiquitous in angiosperms （Slewinski et al., 2012; Slewinski, 2013）.展开更多
Mitogen-activated protein kinase （MAPK） and leucine-rich repeat receptor-like kinase （LRR-RLK） signaling pathways have been shown to regulate diverse aspects of plant growth and development. In Arabidopsis, proper...Mitogen-activated protein kinase （MAPK） and leucine-rich repeat receptor-like kinase （LRR-RLK） signaling pathways have been shown to regulate diverse aspects of plant growth and development. In Arabidopsis, proper anther development relies on intercellular communication to coordinate cell proliferation and differentiation. Two closely related genes encoding MAPKs, MPK3 and MPK6, function redundantly in regulating stomatal patterning. Although the mpk6 mutant has reduced fertility, the function of MPK3 and MPK6 in anther development has not been characterized. Similarly, the ERECTA （ER）, ERECTA-LIKE1 （ERL1） and ERL2 genes encoding LRR-RLKs function together to direct stomatal cell fate specification and the er-105 erll-2 erl2-1 triple mutant is sterile. Because the mpk3 rnpk6 double null mutant is embryo lethal, anther development was characterized in the viable mpk3/＋ mpk6/- and er-105 erll-2 erl2-1 mutants. We found that both mutant anthers usually fail to form one or more of the four anther lobes, with the er-105 erl1-2 erl2-1 triple mutant exhibiting more severe phenotypes than those of the mpk3/＋ mpk6/- mutant. The somatic cell layers of the differentiated mutant lobes appeared larger and more disorganized than that of wild-type. In addition, the er-105 erll-2 erl2ol triple mutant has a reduced number of stamens, the majority of which possess completely undifferentiated or under-differentiated anthers. Furthermore, sometimes, the mpk3/＋ mpk6/- mutant anthers do not dehisce, and the er-105 erl1-2 erl2-1 anthers were not observed to dehisce. Therefore, our results indicate that both ER/ERL 1/ERL2 and MPK3/MPK6 play important roles in normal anther lobe formation and anther cell differentiation. The close functional relationship between these genes in other developmental processes and the similarities in anther developmental phenotypes of the two types of mutants reported here further suggest the possibility that these genes might also function in the same pathway to regulate anther cell division and differentiation.展开更多
Sugarcane borer, Diatraea saccharalis （E）, is a major target of transgenic maize expressing Bacillus thuringiensis （Bt） proteins in South America and the US mid- south region. Resistance development in target pest...Sugarcane borer, Diatraea saccharalis （E）, is a major target of transgenic maize expressing Bacillus thuringiensis （Bt） proteins in South America and the US mid- south region. Resistance development in target pest populations is a major threat to the sustainable use of Bt crops. In our field trials in 2009, a significant number of live borers and plant injury fi＇om D. saccharalis were observed in an experimental SmartStaxTM maize line. The objective of this study was to assess the relative susceptibility of two field popula- tions ofD. saccharalis collected from non-Bt and Bt maize plants containing SmartStaxTM traits to five individual Cry proteins. The five Bt proteins included two proteins （Cry 1A. 105 and Cry2Ab2） that were expressed in SmartStaxTM maize plants and three other common Bt proteins （Cry 1Aa, Cry 1Ab and Cry l Ac） that were not produced in SmartStaxTM. Larval mortality and growth inhibition on Bt diet of the fourth generation after field collections were evaluated 7 days after release of neonates on the diet surface. The laboratory bioassays showed that 50% lethal concentration （LCs0） values for CrylA. 105 and Cry2Ab2 for the population originated from Bt plants were 3.55- and 1.34-fold greater, respectively, than those of the population collected from non-Bt plants. In contrast, relative to the popula- tion from non-Bt plants, the LCs0 of the population sampled from Bt plants were 3.85-, 2.5- and 1.64-fold more sensitive to CrylAa, CrylAb and CrylAc, respectively. The re- sults did not provide clear evidence to conclude that the observed field survival of D. saccharalis on Bt plants was associated with increased levels of resistance.展开更多
Nutrient sensing and signaling is an important area of plant biological research because of the role of plant nutrition in crop production and the constraints that nutrient limita- tions put on plant growth and optima...Nutrient sensing and signaling is an important area of plant biological research because of the role of plant nutrition in crop production and the constraints that nutrient limita- tions put on plant growth and optimal yields. The increasing cost, the limited supplies, and the negative impacts of excess application of fertilizer on the environment have all led to more research into understanding how plants acquire, sense, and utilize nutrients. Approximately two and a half years ago, Molecular Plant published a special issue （March 2010） with a series of review articles and ori- ginal research papers on nutrient sensing and signaling. Many reviews have appeared and provide excellent sum- maries for research advances in this area （Ho and Tsay, 2010; Krouk et al., 2010a; Chiou and Lin, 2011; Gutierrez, 2012）. This highlight updates readers on some of the advances and emerging themes in this field of research since the special issue.展开更多
基金This study was partially funded by the Robert E.Basye Endowment in Rose Genetics,the USDA’s National Institute of Food and Agriculture(NIFA)Specialty Crop Research Initiative projects,“RosBREED:Combining Disease Resistance with Horticultural Quality in New Rosaceous Cultivars”and“Combating Rose Rosette Disease:Short Term and Long Term Approaches”and the China Scholarship Council.
文摘Roses,which have been cultivated for at least 5000 years,are one of the most important ornamental crops in the world.Because of the interspecific nature and high heterozygosity in commercial roses,the genetic resources available for rose are limited.To effectively identify markers associated with QTL controlling important traits,such as disease resistance,abundant markers along the genome and careful phenotyping are required.Utilizing genotyping by sequencing technology and the strawberry genome(Fragaria vesca v2.0.a1)as a reference,we generated thousands of informative single nucleotide polymorphism(SNP)markers.These SNPs along with known bridge simple sequence repeat(SSR)markers allowed us to create the first high-density integrated consensus map for diploid roses.Individual maps were first created for populations J06-20-14-3דLittle Chief”(J14-3×LC),J06-20-14-3דVineyard Song”(J14-3×VS)and“Old Blush”דRed Fairy”(OB×RF)and these maps were linked with 824 SNPs and 13 SSR bridge markers.The anchor SSR markers were used to determine the numbering of the rose linkage groups.The diploid consensus map has seven linkage groups(LGs),a total length of 892.2 cM,and an average distance of 0.25 cM between 3527 markers.By combining three individual populations,the marker density and the reliability of the marker order in the consensus map was improved over a single population map.Extensive synteny between the strawberry and diploid rose genomes was observed.This consensus map will serve as the tool for the discovery of marker–trait associations in rose breeding using pedigree-based analysis.The high level of conservation observed between the strawberry and rose genomes will help further comparative studies within the Rosaceae family and may aid in the identification of candidate genes within QTL regions.
文摘In this report we have evaluated metabolite and RNA profiling technologies to begin to understand the natural variation in these biomolecules found in commercial-quality, conventional (non-GM) maize hybrids. Our analyses focus on mature grain, the article of commerce that is most typically subjected to the rigorous studies involved in the comparative safety assessment of GM products. We have used a population of conventionally-bred maize hybrids that derive from closely related inbred parents grown under standard field conditions across geographically similar locations. This study highlights the large amount of natural variation in metabolites and transcripts across conventional maize germplasm grown under normal field conditions, and underscores the critical need for further extensive studies before these technologies can be seriously considered for utility in the comparative safety assessment of GM crops.
文摘Over the last two decades, transgenic plants have moved from being solely laboratory vehicles for basic research work to providing new varieties grown on large areas throughout the world. A number of
文摘To develop better varieties for farmers and to increase overall agricultural productivity, Monsanto Company has continued to lead innovations in plant biotech, breeding and molecular breeding. In Molecular breeding, non-
文摘Informative,portable,and efficient DNA markers have the potential to accelerate genetic gain in cotton breeding.Discovery and widespread application of DNA markers to cotton has
文摘Nitrogen fertilization is one of the greatest challenges associated with the production of biofuel from corn grain. The objective of this research was to determine the effect of N fertilization on the content and yield of oil, protein, and starch in corn grain. The project was done in Southeast Missouri （USA）, from 2007 to 2009 in a silt loam soil. Corn grain contains 3.8-4.2% oil, 6.7%-8.9% protein, 68.0%-70.4% extractable starch, and 76.0%-77.7% total starch. The total starch yield ranged from 2.8 to 7.8 mg.ha1 whereas the extractable starch varied between 2.5 to 7.1 mg-ha1. As the N rate went up, the oil and starch content of the grain decreased, whereas the protein content and the protein, starch, and oil yields increased, reaching their maximum at the N rate corresponding to 179.0 kg N.ha~. The potential ethanol yield varied between 616.2 and 7,035.1 L-ha1 depending on the method of conversion of the starch into ethanol, the year and the N rate （P 〈 0.0001）. The negative correlation between N fertilization rate and starch content suggested that when farmers add too much N to their soil to increase grain yield, they reduce the starch content in those grains, and consequently the conversion into bioethanol. Therefore, for biofuel production to be beneficial for both farmers and the power plant owners, an agreement needs to be made with regard to the use of fertilizers.
文摘Reactive oxygen species （ROS） play an important role in root responses to potassium deprivation by regulating the expression of the high-affinity K＋ transporter gene AtHAK5 and other genes. Activation-tagged lines of Arabidopsis plants containing the AtHAK5 promoter driving luciferase were screened for bioluminescence under potassium- sufficient conditions. A member of the type Ill peroxidase family, RCI3, was isolated and when it was overexpressed by the activation tag, this led to the enhanced expression of luciferase and the endogenous AtHAKS. RCI3 was found to be up- regulated upon potassium deprivation. Plants overexpressing RCI3 （RCI3-ox） showed more ROS production and AtHAK5 expression whereas the ROS production and AtHAK5 expression were reduced in rci3-1 under K＋-deprived conditions. These results suggested that RCI3 is involved in the production of ROS under potassium deprivation and that RCI3- mediated ROS production affects the regulation of AtHAK5 expression. This peroxidase appears to be another component of the low-potassium signal transduction pathway in Arabidopsis roots.
文摘Plants respond to low-nutrient conditions through metabolic and morphology changes that increase their ability to survive and grow. The transcription factor RAP2.11 was identified as a component in the response to low potassium through regulation of the high-affinity K＋ uptake transporter AtHAK5 and other components of the low- potassium signal transduction pathway. RAP2.11 was identified through the activation tagging of Arabidopsis lines that contained a luciferase marker driven by the AtHAK5 promoter that is normally only induced by low potassium. This factor bound to a GCC-box of the AtHAK5 promoter in vitro and in vivo. Transcript profiling revealed that a large number of genes were up-regulated in roots by RAP2.11 overexpression. Many regulated genes were identified to be in functional cate- gories that are important in Iow-K＋ signaling. These categories included ethylene signaling, reactive oxygen species pro- duction, and calcium signaling. Promoter regions of the up-regulated genes were enriched in the GCCGGC motif also contained in the AtHAK5 promoter. These results suggest that RAP2.11 regulates AtHAK5 expression under Iow-K＋ con- ditions and also contributes to a coordinated response to low-potassium conditions through the regulation of other genes in the Iow-K＋ signaling cascade.
文摘The sugarcane borer, Diatraea saccharalis （E）, is a major maize borer pest and a target of transgenic maize expressing Bacillus thuringiensis （Bt） proteins in South America and the mid-southern region of the United States. Evolution of resistance in target pest populations is a great threat to the long-term efficacy of Bt crops. In this study, we compared the genetic basis of resistance to CrylAb protein in 3 resistant colonies of sugarcane borer established from field populations in Louisiana, USA. Responses of larvae to the CrylAb protein for the parental and 10 other cross colonies were assayed in a diet-incorporated bioassay. All 3 resistant colonies were highly resistant to the CrylAb protein with a resistance ratio of 〉 5 5 5.6 fold. No maternal effect or sex linkage was evident for the resistance in the 3 colonies; and the resistance was functionally nonrecessive at the CrylAb concentrations of 〈 3.16 μg/g, but it became recessive at 〉10μg/g. In an interstrain complementation test for allelism, the Fl progeny from crosses between any 2 of the 3 resistant colonies exhibited the similar resistance levels as their parental colonies, indicating that the 3 colonies most likely shared a locus of CrylAb resistance. Results generated from this study should provide useful information in developing effective strategies for managing Bt resistance in the insect.
文摘Western corn rootworm （WCR, Diabrotica virgifera virgifera LeConte） is highly sensitive to orally delivered double-stranded RNA （dsRNA）. RNAi in WCR is systemic and spreads throughout the insect body. This raises the question whether transitive RNAi is a mechanism that functions in WCR to amplify the RNAi response via production of secondary siRNA. Secondary siRNA production is achieved through RNA-dependent RNA polymerase （RdRP） activity in other eukaryotic organisms, but RdRP has not been identified in WCR and any other insects. This study visualized the spread of the RNAi- mediated knockdown of Dr v-ATPase C mRNA throughout the WCR gut and other tissues using high-sensitivity branched DNA in situ hybridization. Furthermore, we did not detect either secondary siRNA production or transitive RNAi in WCR through siRNA sequence profile analysis. Nucleotide mismatched sequences introduced into either the sense or antisense strand of v-ATPase C dsRNAs were maintained in siRNAs derived from WCR fed with the mismatched dsRNAs in a strand specific manner. The distribution of all siRNAs was restricted to within the original target sequence regions, which may indicate the lack of new dsRNA synthesis leading to production of secondary siRNA. Thus, the systemic spread of RNAi in WCR may be derived from the original dsRNA molecules taken up from the gut lumen. These results indicate that the initial dsRNA dose is important for a lethal systemic RNAi response in WCR and have implications in developing effective dsRNA traits to control WCR and in resistance management to prolong the durability of RNAi trait technology.
文摘Dear Editor, Understanding how Kranz anatomy develops in C4 plants is a critical part of the current worldwide effort to transfer C4 photosynthesis into C3 plants, including rice. Recently, it was proposed that the Kranz architecture that supports C4 photosynthesis in maize leaves is an extension of the endodermal program, which is active in roots, stems, and petioles, and is ubiquitous in angiosperms （Slewinski et al., 2012; Slewinski, 2013）.
文摘Mitogen-activated protein kinase （MAPK） and leucine-rich repeat receptor-like kinase （LRR-RLK） signaling pathways have been shown to regulate diverse aspects of plant growth and development. In Arabidopsis, proper anther development relies on intercellular communication to coordinate cell proliferation and differentiation. Two closely related genes encoding MAPKs, MPK3 and MPK6, function redundantly in regulating stomatal patterning. Although the mpk6 mutant has reduced fertility, the function of MPK3 and MPK6 in anther development has not been characterized. Similarly, the ERECTA （ER）, ERECTA-LIKE1 （ERL1） and ERL2 genes encoding LRR-RLKs function together to direct stomatal cell fate specification and the er-105 erll-2 erl2-1 triple mutant is sterile. Because the mpk3 rnpk6 double null mutant is embryo lethal, anther development was characterized in the viable mpk3/＋ mpk6/- and er-105 erll-2 erl2-1 mutants. We found that both mutant anthers usually fail to form one or more of the four anther lobes, with the er-105 erl1-2 erl2-1 triple mutant exhibiting more severe phenotypes than those of the mpk3/＋ mpk6/- mutant. The somatic cell layers of the differentiated mutant lobes appeared larger and more disorganized than that of wild-type. In addition, the er-105 erll-2 erl2ol triple mutant has a reduced number of stamens, the majority of which possess completely undifferentiated or under-differentiated anthers. Furthermore, sometimes, the mpk3/＋ mpk6/- mutant anthers do not dehisce, and the er-105 erl1-2 erl2-1 anthers were not observed to dehisce. Therefore, our results indicate that both ER/ERL 1/ERL2 and MPK3/MPK6 play important roles in normal anther lobe formation and anther cell differentiation. The close functional relationship between these genes in other developmental processes and the similarities in anther developmental phenotypes of the two types of mutants reported here further suggest the possibility that these genes might also function in the same pathway to regulate anther cell division and differentiation.
文摘Sugarcane borer, Diatraea saccharalis （E）, is a major target of transgenic maize expressing Bacillus thuringiensis （Bt） proteins in South America and the US mid- south region. Resistance development in target pest populations is a major threat to the sustainable use of Bt crops. In our field trials in 2009, a significant number of live borers and plant injury fi＇om D. saccharalis were observed in an experimental SmartStaxTM maize line. The objective of this study was to assess the relative susceptibility of two field popula- tions ofD. saccharalis collected from non-Bt and Bt maize plants containing SmartStaxTM traits to five individual Cry proteins. The five Bt proteins included two proteins （Cry 1A. 105 and Cry2Ab2） that were expressed in SmartStaxTM maize plants and three other common Bt proteins （Cry 1Aa, Cry 1Ab and Cry l Ac） that were not produced in SmartStaxTM. Larval mortality and growth inhibition on Bt diet of the fourth generation after field collections were evaluated 7 days after release of neonates on the diet surface. The laboratory bioassays showed that 50% lethal concentration （LCs0） values for CrylA. 105 and Cry2Ab2 for the population originated from Bt plants were 3.55- and 1.34-fold greater, respectively, than those of the population collected from non-Bt plants. In contrast, relative to the popula- tion from non-Bt plants, the LCs0 of the population sampled from Bt plants were 3.85-, 2.5- and 1.64-fold more sensitive to CrylAa, CrylAb and CrylAc, respectively. The re- sults did not provide clear evidence to conclude that the observed field survival of D. saccharalis on Bt plants was associated with increased levels of resistance.
文摘Nutrient sensing and signaling is an important area of plant biological research because of the role of plant nutrition in crop production and the constraints that nutrient limita- tions put on plant growth and optimal yields. The increasing cost, the limited supplies, and the negative impacts of excess application of fertilizer on the environment have all led to more research into understanding how plants acquire, sense, and utilize nutrients. Approximately two and a half years ago, Molecular Plant published a special issue （March 2010） with a series of review articles and ori- ginal research papers on nutrient sensing and signaling. Many reviews have appeared and provide excellent sum- maries for research advances in this area （Ho and Tsay, 2010; Krouk et al., 2010a; Chiou and Lin, 2011; Gutierrez, 2012）. This highlight updates readers on some of the advances and emerging themes in this field of research since the special issue.
