RESUMO
MAIN CONCLUSION: Agrobacterium-mediated transformation of Nicotiana tabacum, using an intragenic T-DNA region derived entirely from the N. tabacum genome, results in the equivalence of micro-translocations within genomes. Intragenic Agrobacterium-mediated gene transfer was achieved in Nicotiana tabacum using a T-DNA composed entirely of N. tabacum DNA, including T-DNA borders and the acetohydroxyacid synthase gene conferring resistance to sulfonylurea herbicides. Genomic analysis of a resulting plant, with single locus inheritance of herbicide resistance, identified a single insertion of the intragenic T-DNA on chromosome 5. The insertion event was composed of three N. tabacum DNA fragments from other chromosomes, as assembled on the T-DNA vector. This validates that intragenic transformation of plants can mimic micro-translocations within genomes, with the absence of foreign DNA.
Assuntos
Acetolactato Sintase , Rearranjo Gênico , Translocação Genética , DNA , Agrobacterium/genética , Nicotiana/genéticaRESUMO
KEY MESSAGE: An improved estimator of genomic relatedness using low-depth high-throughput sequencing data for autopolyploids is developed. Its outputs strongly correlate with SNP array-based estimates and are available in the package GUSrelate. High-throughput sequencing (HTS) methods have reduced sequencing costs and resources compared to array-based tools, facilitating the investigation of many non-model polyploid species. One important quantity that can be computed from HTS data is the genetic relatedness between all individuals in a population. However, HTS data are often messy, with multiple sources of errors (i.e. sequencing errors or missing parental alleles) which, if not accounted for, can lead to bias in genomic relatedness estimates. We derive a new estimator for constructing a genomic relationship matrix (GRM) from HTS data for autopolyploid species that accounts for errors associated with low sequencing depths, implemented in the R package GUSrelate. Simulations revealed that GUSrelate performed similarly to existing GRM methods at high depth but reduced bias in self-relatedness estimates when the sequencing depth was low. Using a panel consisting of 351 tetraploid potato genotypes, we found that GUSrelate produced GRMs from genotyping-by-sequencing (GBS) data that were highly correlated with a GRM computed from SNP array data, and less biased than existing methods when benchmarking against the array-based GRM estimates. GUSrelate provides researchers with a tool to reliably construct GRMs from low-depth HTS data.
Assuntos
Técnicas de Genotipagem , Polimorfismo de Nucleotídeo Único , Humanos , Técnicas de Genotipagem/métodos , Análise de Sequência de DNA/métodos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , AlelosRESUMO
BACKGROUND: A frequent problem associated with the tissue culture of Compositae species such as chicory (Cichorium intybus L.) and lettuce (Lactuca sativa L.) is the premature bolting to in vitro flowering of regenerated plants. Plants exhibiting such phase changes have poor survival and poor seed set upon transfer from tissue culture to greenhouse conditions. This can result in the loss of valuable plant lines following applications of cell and tissue culture for genetic manipulation. RESULTS: This study demonstrates that chicory and lettuce plants exhibiting stable in vitro flowering can be rejuvenated by a further cycle of adventitious shoot regeneration from cauline leaves. The resulting rejuvenated plants exhibit substantially improved performance following transfer to greenhouse conditions, with increased frequency of plant survival, a doubling of the frequency of plants that flowered, and substantially increased seed production. CONCLUSION: As soon as in vitro flowering is observed in unique highly-valued chicory and lettuce lines, a further cycle of adventitious shoot regeneration from cauline leaves should be implemented to induce rejuvenation. This re-establishes a juvenile phase accompanied by in vitro rosette formation, resulting in substantially improved survival, flowering and seed set in a greenhouse, thereby ensuring the recovery of future generations from lines genetically manipulated in cell and tissue culture.
Assuntos
Cichorium intybus/fisiologia , Lactuca/fisiologia , Cichorium intybus/citologia , Lactuca/citologia , Folhas de Planta/citologia , Folhas de Planta/fisiologia , Rejuvenescimento/fisiologia , Técnicas de Cultura de Tecidos/métodosRESUMO
BACKGROUND: Somatic cell selection in plants allows the recovery of spontaneous mutants from cell cultures. When coupled with the regeneration of plants it allows an effective approach for the recovery of novel traits in plants. This study undertook somatic cell selection in the potato (Solanum tuberosum L.) cultivar 'Iwa' using the sulfonylurea herbicide, chlorsulfuron, as a positive selection agent. RESULTS: Following 5 days' exposure of potato cell suspension cultures to 20 µg/l chlorsulfuron, rescue selection recovered rare potato cell colonies at a frequency of approximately one event in 2.7 × 105 of plated cells. Plants that were regenerated from these cell colonies retained resistance to chlorsulfuron and two variants were confirmed to have different independent point mutations in the acetohydroxyacid synthase (AHAS) gene. One point mutation involved a transition of cytosine for thymine, which substituted the equivalent of Pro-197 to Ser-197 in the AHAS enzyme. The second point mutation involved a transversion of thymine to adenine, changing the equivalent of Trp-574 to Arg-574. The two independent point mutations recovered were assembled into a chimeric gene and binary vector for Agrobacterium-mediated transformation of wild-type 'Iwa' potato. This confirmed that the mutations in the AHAS gene conferred chlorsulfuron resistance in the resulting transgenic plants. CONCLUSIONS: Somatic cell selection in potato using the sulfonylurea herbicide, chlorsulfuron, recovered resistant variants attributed to mutational events in the AHAS gene. The mutant AHAS genes recovered are therefore good candidates as selectable marker genes for intragenic transformation of potato.
Assuntos
Acetolactato Sintase/genética , Marcadores Genéticos/genética , Plantas Geneticamente Modificadas/fisiologia , Mutação Puntual/genética , Seleção Genética/genética , Solanum tuberosum/efeitos dos fármacos , Solanum tuberosum/fisiologia , Sulfonamidas/administração & dosagem , Triazinas/administração & dosagem , Acetolactato Sintase/metabolismo , Resistência a Herbicidas/genética , Herbicidas/administração & dosagem , Células Vegetais/enzimologia , Células Vegetais/metabolismoRESUMO
Integrative and conjugative elements (ICEs) contribute to the rapid evolution of bacterial pathogens via horizontal gene transfer of virulence determinants. ICEs have common mechanisms for transmission, yet the cues triggering this process under natural environmental or physiological conditions are largely unknown. In this study, mobilization of the putative ICE horizontally acquired island 2 (HAI2), present in the chromosome of the phytopathogen Pectobacterium atrosepticumâ SCRI1043, was examined during infection of the host plant potato. Under these conditions, mobilization of HAI2 increased markedly compared with in vitro cultures. In planta-induced mobilization of HAI2 was regulated by quorum sensing and involved the putative ICE-encoded relaxase ECA0613. Disruption of ECA0613 also reduced transcription of genes involved in production of coronafacic acid (Cfa), the major virulence factor harboured on HAI2, whereas their expression was unaffected in the quorum-sensing (expI) mutant. Thus, suppression of cfa gene expression was not regulated by the mobilization of the ICEâ per se, but was due directly to inactivation of the relaxase. The identification of genetic factors associated solely with in planta mobilization of an ICE demonstrates that this process is highly adapted to the natural environment of the bacterial host and can influence the expression of virulence determinants.
Assuntos
Pectobacterium/genética , Pectobacterium/patogenicidade , Doenças das Plantas/microbiologia , Solanum tuberosum/microbiologia , Fatores de Virulência/genética , Sequência de Aminoácidos , Transferência Genética Horizontal , Indenos/metabolismo , Ilhas , Dados de Sequência Molecular , Pectobacterium/metabolismo , Percepção de Quorum/genética , Alinhamento de Sequência , Fatores de Virulência/metabolismoRESUMO
BACKGROUND: GSL1 and GSL2, Gibberellin Stimulated-Like proteins (also known as Snakin-1 and Snakin-2), are cysteine-rich peptides from potato (Solanum tuberosum L.) with antimicrobial properties. Similar peptides in other species have been implicated in diverse biological processes and are hypothesised to play a role in several aspects of plant development, plant responses to biotic or abiotic stress through their participation in hormone crosstalk, and redox homeostasis. To help resolve the biological roles of GSL1 and GSL2 peptides we have undertaken an in depth analysis of the structure and expression of these genes in potato. RESULTS: We have characterised the full length genes for both GSL1 (chromosome 4) and GSL2 (chromosome 1) from diploid and tetraploid potato using the reference genome sequence of potato, coupled with further next generation sequencing of four highly heterozygous tetraploid cultivars. The frequency of SNPs in GSL1 and GSL2 were very low with only one SNP every 67 and 53 nucleotides in exon regions of GSL1 and GSL2, respectively. Analysis of comprehensive RNA-seq data substantiated the role of specific promoter motifs in transcriptional control of gene expression. Expression analysis based on the frequency of next generation sequence reads established that GSL2 was expressed at a higher level than GSL1 in 30 out of 32 tissue and treatment libraries. Furthermore, both the GSL1 and GSL2 genes exhibited constitutive expression that was not up regulated in response to biotic or abiotic stresses, hormone treatments or wounding. Potato transformation with antisense knock-down expression cassettes failed to recover viable plants. CONCLUSIONS: The potato GSL1 and GSL2 genes are very highly conserved suggesting they contribute to an important biological function. The known antimicrobial activity of the GSL proteins, coupled with the FPKM analysis from RNA-seq data, implies that both genes contribute to the constitutive defence barriers in potatoes. The lethality of antisense knock-down expression of GSL1 and GSL2, coupled with the rare incidence of SNPs in these genes, suggests an essential role for this gene family. These features are consistent with the GSL protein family playing a role in several aspects of plant development in addition to plant defence against biotic stresses.
Assuntos
Genes de Plantas , Giberelinas/genética , Proteínas de Plantas/genética , Solanum tuberosum/genética , Alelos , Cromossomos de Plantas , Biologia Computacional , Sequência Conservada/genética , Diploide , Regulação da Expressão Gênica de Plantas , Giberelinas/química , Giberelinas/metabolismo , Sequenciamento de Nucleotídeos em Larga Escala , Oligonucleotídeos Antissenso/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Polimorfismo de Nucleotídeo Único , Regiões Promotoras Genéticas , Solanum tuberosum/metabolismo , TetraploidiaRESUMO
Over-expression of the potato Gibberellin Stimulated-Like 2 ( GSL2 ) gene in transgenic potato confers resistance to blackleg disease incited by Pectobacterium atrosepticum and confirms a role for GSL2 in plant defence. The Gibberellin Stimulated-Like 2 (GSL2) gene (also known as Snakin 2) encodes a cysteine-rich, low-molecular weight antimicrobial peptide produced in potato plants. This protein is thought to play important roles in the innate defence against invading microbes. Over-expression of the GSL2 gene in potato (cultivar Iwa) was achieved using Agrobacterium-mediated gene transfer of a plant expression vector with the potato GSL2 gene under the regulatory control elements of the potato light-inducible Lhca3 gene. The resulting plants were confirmed as being transgenic by PCR, and subsequently analysed for transcriptional expression of the Lhca3-GSL2-Lhca3 chimeric potato gene. Quantitative RT-PCR analysis demonstrated that the majority of the transgenic potato lines over-expressed the GSL2 gene at the mRNA level. Based on qRT-PCR results and evaluation of phenotypic appearance, eight lines were selected for further characterisation and evaluated in bioassays for resistance to Pectobacterium atrosepticum (formerly Erwinia carotovora subsp. atroseptica), the causal agent of blackleg in potato. Three independent pathogenicity bioassays showed that transgenic lines with significantly increased transcriptional expression of the GSL2 gene exhibit resistance to blackleg disease. This establishes a functional role for GSL2 in plant defence against pathogens in potato.
Assuntos
Resistência à Doença/genética , Genes de Plantas , Pectobacterium , Proteínas de Plantas/genética , Solanum tuberosum/genética , DNA de Plantas/genética , Doenças das Plantas/microbiologia , Proteínas de Plantas/metabolismo , Solanum tuberosum/microbiologiaRESUMO
Potato is the third most important global food crop and the most widely grown noncereal crop. As a species highly amenable to cell culture, it has a long history of biotechnology applications for crop improvement. This review begins with a historical perspective on potato improvement using biotechnology encompassing pathogen elimination, wide hybridization, ploidy manipulation and applications of cell culture. We describe the past developments and new approaches for gene transfer to potato. Transformation is highly effective for adding single genes to existing elite potato clones with no, or minimal, disturbances to their genetic background and represents the only effective way to produce isogenic lines of specific genotypes/cultivars. This is virtually impossible via traditional breeding as, due to the high heterozygosity in the tetraploid potato genome, the genetic integrity of potato clones is lost upon sexual reproduction as a result of allele segregation. These genetic attributes have also provided challenges for the development of genetic maps and applications of molecular markers and genomics in potato breeding. Various molecular approaches used to characterize loci, (candidate) genes and alleles in potato, and associating phenotype with genotype are also described. The recent determination of the potato genome sequence has presented new opportunities for genomewide assays to provide tools for gene discovery and enabling the development of robustly unique marker haplotypes spanning QTL regions. The latter will be useful in introgression breeding and whole-genome approaches such as genomic selection to improve the efficiency of selecting elite clones and enhancing genetic gain over time.
Assuntos
Biotecnologia/tendências , Genômica/tendências , Solanum tuberosum/genética , Bacillus thuringiensis/genética , Toxinas de Bacillus thuringiensis , Proteínas de Bactérias/genética , Resistência à Doença/genética , Endotoxinas/genética , Genoma de Planta , Proteínas Hemolisinas/genética , Doenças das Plantas/genética , Plantas Geneticamente ModificadasRESUMO
Oryctes rhinoceros nudivirus, a double-stranded DNA virus of the family Nudiviridae, is an important biocontrol agent of the coconut rhinoceros beetle (Coleoptera: Scarabaeidae). We present the genome sequences of six isolates of Oryctes rhinoceros nudivirus collected from the Philippines, Papua New Guinea, and Tanzania between the years 1977 and 2016.
RESUMO
In planta the enzymatic activity of apoplastic and vacuolar invertases is controlled by inhibitory proteins. Although these invertase inhibitors (apoplastic and vacuolar forms) have been implicated as contributing to resistance to cold-induced sweetening (CIS) in tubers of potato (Solanum tuberosum L.), there is a lack of information on the structure and allelic diversity of the apoplastic invertase inhibitor genes. We have PCR-isolated and sequenced the alleles of the apoplastic invertase inhibitor gene (Stinh1) from three tetraploid potato genotypes: 1021/1 (a genotype with very high tolerance to CIS), 'Karaka' and 'Summer Delight' (two cultivars that are highly susceptible to CIS). In total, five alleles were identified in these genotypes, of which four (Stinh1-c, Stinh1-d, Stinh1-e, Stinh1-f) were novel. An analysis of allele diversity was conducted by incorporating previously published sequences of apoplastic invertase inhibitors from potato. Eight alleles were assessed for sequence polymorphism in the two exons and the single hypervariable intron. Contrary to the hypervariable intron, only 65 single nucleotide polymorphisms were observed in the exons, of which 42 confer amino acid substitutions. Phylogenetic analysis of amino acid sequences indicates that the alleles of the invertase inhibitor are highly conserved amongst members of the Solanaceae family.
Assuntos
Genes de Plantas , Solanum tuberosum/genética , Alelos , Sequência de Aminoácidos , Sequência de Bases , Temperatura Baixa , DNA de Plantas/genética , Éxons , Variação Genética , Íntrons , Dados de Sequência Molecular , Filogenia , Proteínas de Plantas/genética , Polimorfismo de Nucleotídeo Único , Homologia de Sequência de Aminoácidos , Solanum tuberosum/metabolismo , Tetraploidia , beta-Frutofuranosidase/antagonistas & inibidoresRESUMO
Self-incompatibility (SI) is a feature of many flowering plants, whereby self-pollen is recognized and rejected by the stigma. In grasses (Poaceae), the genes controlling this phenomenon have not been fully elucidated. Grasses have a unique two-locus system, in which two independent genetic loci (S and Z) control self-recognition. S and Z are thought to have arisen from an ancient duplication, common to all grasses. With new chromosome-scale genome data, we examined the genes present at S- and Z-loci, firstly in ryegrass (Lolium perenne), and subsequently in ~20 other grass species. We found that two DUF247 genes and a short unstructured protein (SP/ZP) were present at both S- and Z- in all SI species, while in self-compatible species these genes were often lost or mutated. Expression data suggested that DUF247 genes acted as the male components and SP/ZP were the female components. Consistent with their role in distinguishing self- from non-self, all genes were hypervariable, although key secondary structure features were conserved, including the predicted N-terminal cleavage site of SP/ZP. The evolutionary history of these genes was probed, revealing that specificity groups at the Z-locus arose before the advent of various grass subfamilies/species, while specificity groups at the S-locus arose after the split of Panicoideae, Chloridoideae, Oryzoideae and Pooideae. Finally, we propose a model explaining how the proteins encoded at the S and Z loci might function to specify self-incompatibility.
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BACKGROUND: The recovery of high performing transgenic lines in clonal crops is limited by the occurrence of somaclonal variation during the tissue culture phase of transformation. This is usually circumvented by developing large populations of transgenic lines, each derived from the first shoot to regenerate from each transformation event. This study investigates a new strategy of assessing multiple shoots independently regenerated from different transformed cell colonies of potato (Solanum tuberosum L.). RESULTS: A modified cry9Aa2 gene, under the transcriptional control of the CaMV 35S promoter, was transformed into four potato cultivars using Agrobacterium-mediated gene transfer using a nptII gene conferring kanamycin resistance as a selectable marker gene. Following gene transfer, 291 transgenic lines were grown in greenhouse experiments to assess somaclonal variation and resistance to potato tuber moth (PTM), Phthorimaea operculella (Zeller). Independently regenerated lines were recovered from many transformed cell colonies and Southern analysis confirmed whether they were derived from the same transformed cell. Multiple lines regenerated from the same transformed cell exhibited a similar response to PTM, but frequently exhibited a markedly different spectrum of somaclonal variation. CONCLUSIONS: A new strategy for the genetic improvement of clonal crops involves the regeneration and evaluation of multiple shoots from each transformation event to facilitate the recovery of phenotypically normal transgenic lines. Most importantly, regenerated lines exhibiting the phenotypic appearance most similar to the parental cultivar are not necessarily derived from the first shoot regenerated from a transformed cell colony, but can frequently be a later regeneration event.
Assuntos
Agrobacterium tumefaciens/genética , Proteínas de Bactérias/genética , Biotecnologia/métodos , Endotoxinas/genética , Proteínas Hemolisinas/genética , Larva/efeitos dos fármacos , Brotos de Planta/genética , Solanum tuberosum/genética , Animais , Toxinas de Bacillus thuringiensis , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/farmacologia , Southern Blotting , Endotoxinas/metabolismo , Endotoxinas/farmacologia , Técnicas de Transferência de Genes , Marcadores Genéticos , Variação Genética , Proteínas Hemolisinas/metabolismo , Proteínas Hemolisinas/farmacologia , Inseticidas/metabolismo , Inseticidas/farmacologia , Larva/fisiologia , Mariposas/efeitos dos fármacos , Mariposas/fisiologia , Brotos de Planta/imunologia , Brotos de Planta/metabolismo , Técnicas de Embriogênese Somática de Plantas , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas , Regeneração , Solanum tuberosum/imunologia , Solanum tuberosum/metabolismoRESUMO
Events of inbreeding are inevitable in critically endangered species. Reduced population sizes and unique life-history traits can increase the severity of inbreeding, leading to declines in fitness and increased risk of extinction. Here, we investigate levels of inbreeding in a critically endangered flightless parrot, the kakapo (Strigops habroptilus), wherein a highly inbred island population and one individual from the mainland of New Zealand founded the entire extant population. Genotyping-by-sequencing (GBS), and a genotype calling approach using a chromosome-level genome assembly, identified a filtered set of 12,241 single-nucleotide polymorphisms (SNPs) among 161 kakapo, which together encompass the total genetic potential of the extant population. Multiple molecular-based estimates of inbreeding were compared, including genome-wide estimates of heterozygosity (FH), the diagonal elements of a genomic-relatedness matrix (FGRM), and runs of homozygosity (RoH, FRoH). In addition, we compared levels of inbreeding in chicks from a recent breeding season to examine if inbreeding is associated with offspring survival. The density of SNPs generated with GBS was sufficient to identify chromosomes that were largely homozygous with RoH distributed in similar patterns to other inbred species. Measures of inbreeding were largely correlated and differed significantly between descendants of the two founding populations. However, neither inbreeding nor ancestry was found to be associated with reduced survivorship in chicks, owing to unexpected mortality in chicks exhibiting low levels of inbreeding. Our study highlights important considerations for estimating inbreeding in critically endangered species, such as the impacts of small population sizes and admixture between diverse lineages.
Assuntos
Endogamia , Papagaios , Animais , Genoma , Genômica , Genótipo , Homozigoto , Polimorfismo de Nucleotídeo ÚnicoRESUMO
MYB transcription factors play important roles in transcriptional regulation of many secondary metabolites including anthocyanins. We cloned the R2R3-MYB type IbMYB1 complementary DNAs from the purple-fleshed sweet potato (Ipomoea batatas L. cv Sinzami) and investigated the expression patterns of IbMYB1 gene with IbMYB1a and IbMYB1b splice variants in leaf and root tissues of various sweet potato cultivars by reverse transcription-polymerase chain reaction. The transcripts of IbMYB1 were predominantly expressed in the purple-fleshed storage roots and they were also detectable in the leaf tissues accumulating anthocyanin pigments. In addition, transcript levels of IbMYB1 gene were up-regulated by treatment with methyl jasmonate or salicylic acid in leaf and root tissues of cv. White Star. To set up the intragenic vector system in sweet potato, we first evaluated the utilization of the IbMYB1 gene as a visible selectable marker. The IbMYB1a was transiently expressed in tobacco leaves under the control of a constitutive cauliflower mosaic virus 35S promoter, a root-specific and sucrose-inducible sporamin promoter, and an oxidative stress-inducible sweet potato anionic peroxidase2 promoter. We also showed that overexpression of IbMYB1a induced massive anthocyanin pigmentation in tobacco leaves and up-regulated the transcript levels of the structural genes in anthocyanin biosynthetic pathway. Furthermore, high-performance liquid chromatography analysis revealed that the expression of IbMYB1a led to production of cyanidin as a major core molecule of anthocyanidins in tobacco leaves. These results suggest that the IbMYB1 gene can be applicable to a visible marker for sweet potato transformation with intragenic vectors, as well as the production of anthocyanin as important nutritive value in other plant species.
Assuntos
Antocianinas/biossíntese , Ipomoea batatas/genética , Proteínas de Plantas/metabolismo , Fatores de Transcrição/metabolismo , Acetatos/farmacologia , Processamento Alternativo , Ciclopentanos/farmacologia , DNA Complementar/genética , Regulação da Expressão Gênica de Plantas , Marcadores Genéticos , Vetores Genéticos , Ipomoea batatas/metabolismo , Oxilipinas/farmacologia , Folhas de Planta/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Tubérculos/genética , Tubérculos/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , RNA de Plantas/genética , Ácido Salicílico/farmacologia , Nicotiana/genética , Nicotiana/metabolismo , Fatores de Transcrição/genética , Transformação GenéticaRESUMO
Tubers are vegetative reproduction organs formed from underground extensions of the plant stem. Potato tubers are harvested and stored for months. Storage under cold temperatures of 2-4⯰C is advantageous for supressing sprouting and diseases. However, development of reducing sugars can occur with cold storage through a process called cold-induced sweetening (CIS). CIS is undesirable as it leads to darkened color with fry processing. The purpose of the current study was to find differences in biological responses in eight cultivars with variation in CIS resistance. Transcriptome sequencing was done on tubers before and after cold storage and three approaches were taken for gene expression analysis: 1. Gene expression correlated with end-point glucose after cold storage, 2. Gene expression correlated with increased glucose after cold storage (after-before), and 3. Differential gene expression before and after cold storage. Cultivars with high CIS resistance (low glucose after cold) were found to increase expression of an invertase inhibitor gene and genes involved in DNA replication and repair after cold storage. The cultivars with low CIS resistance (high glucose after cold) showed increased expression of genes involved in abiotic stress response, gene expression, protein turnover and the mitochondria. There was a small number of genes with similar expression patterns for all cultivars including genes involved in cell wall strengthening and phospholipases. It is proposed that the pattern of gene expression is related to chilling-induced DNA damage repair and cold acclimation and that genetic variation in these processes are related to CIS.
Assuntos
Solanum tuberosum , Temperatura Baixa , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Tubérculos , beta-FrutofuranosidaseRESUMO
Modified, agricultural landscapes are susceptible to damage by insect pests. Biological control of pests is typically successful once a control agent has established, but this depends on the agent's capacity to co-evolve with the host. Theoretical studies have shown that different levels of genetic variation between the host and the control agent will lead to rapid evolution of resistance in the host. Although this has been reported in one instance, the underlying genetics have not been studied. To address this, we measured the genetic variation in New Zealand populations of the pasture pest, Argentine stem weevil (Listronotus bonariensis), which is controlled with declining effectiveness by a parasitoid wasp, Microctonus hyperodae. We constructed a draft reference genome of the weevil, collected samples from a geographical survey of 10 sites around New Zealand, and genotyped them using a modified genotyping-by-sequencing approach. New Zealand populations of Argentine stem weevil have high levels of heterozygosity and low population structure, consistent with a large effective population size and frequent gene flow. This implies that Argentine stem weevils were able to evolve more rapidly than their biocontrol agent, which reproduces asexually. These findings show that monitoring genetic diversity in biocontrol agents and their targets is critical for long-term success of biological control.
RESUMO
Disease resistance is an important objective of global potato breeding programmes. The use of resistant cultivars is a significant tool for disease management. Recent advances in plant molecular genetics have identified several genes for resistance to potato diseases from within the germplasm pool available to potato breeders. Antimicrobial peptides, such as Snakin-1 (StSN1) and Snakin-2 (StSN2), have been isolated recently from potato tubers. Overexpression of the StSNI and StSN2 genes in potato is known to provide broad spectrum activity against a wide range of bacterial and fungal pathogens. We describe the use of intragenic gene transfer technology towards disease resistance in potatoes. An expression cassette was constructed with the 5' promoter and 3' terminator regions of a potato gene encoding a chlorophyll a/b binding protein (StLhca3). The coding regions of the StSN1 and StSN2 genes of potato were cloned individually between these regulatory regions. The resulting Lhca3-StSNi-Lhca3 and Lhca3-StSN2-Lhco3 chimeric genes were individually cloned into a potato-derived T-DNA-like region for potato transformation. Potato cultivar Iwa was co-cultivated with Agrobocterium harbouring intragenic binary vectors with the StSN1 and StSN2 genes. Regenerated potato plants were screened using PCR to identify lines transformed with the disease resistance genes without the presence of foreign DNA.
Assuntos
Imunidade Inata/genética , Doenças das Plantas/genética , Solanum tuberosum/genética , Sequência de Bases , Primers do DNA , DNA de Plantas/genética , DNA de Plantas/isolamento & purificação , Vetores Genéticos , Íntrons/genética , Dados de Sequência Molecular , Doenças das Plantas/prevenção & controle , Proteínas de Plantas/análise , Proteínas de Plantas/genética , Brotos de Planta/genética , Reação em Cadeia da Polimerase , Regiões Terminadoras GenéticasRESUMO
The production of dairy, meat, and fiber by ruminant animals relies on the biological processes occurring in soils, forage plants, and the animals' rumens. Each of these components has an associated microbiome, and these have traditionally been viewed as distinct ecosystems. However, these microbiomes operate under similar ecological principles and are connected via water, energy flows, and the carbon and nitrogen nutrient cycles. Here, we summarize the microbiome research that has been done in each of these three environments (soils, forage plants, animals' rumen) and investigate what additional benefits may be possible through understanding the interactions between the various microbiomes. The challenge for future research is to enhance microbiome function by appropriate matching of plant and animal genotypes with the environment to improve the output and environmental sustainability of pastoral agriculture.
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The advent of Next-Generation sequencing-by-synthesis technologies has fuelled SNP discovery, genotyping, and screening of populations in myriad ways for many species, including various plant species. One technique widely applied to screening a large number of SNP markers over a large number of samples is the Illumina Infinium™ assay.
Assuntos
Técnicas de Genotipagem/métodos , Plantas/genética , Polimorfismo de Nucleotídeo Único/genética , Genoma de Planta , Indicadores e Reagentes , PoliploidiaRESUMO
The genome of potato, a major global food crop, was recently sequenced. The work presented here details the integration of the potato reference genome (DM) with a new sequence-tagged site marker-based linkage map and other physical and genetic maps of potato and the closely related species tomato. Primary anchoring of the DM genome assembly was accomplished by the use of a diploid segregating population, which was genotyped with several types of molecular genetic markers to construct a new ~936 cM linkage map comprising 2469 marker loci. In silico anchoring approaches used genetic and physical maps from the diploid potato genotype RH89-039-16 (RH) and tomato. This combined approach has allowed 951 superscaffolds to be ordered into pseudomolecules corresponding to the 12 potato chromosomes. These pseudomolecules represent 674 Mb (~93%) of the 723 Mb genome assembly and 37,482 (~96%) of the 39,031 predicted genes. The superscaffold order and orientation within the pseudomolecules are closely collinear with independently constructed high density linkage maps. Comparisons between marker distribution and physical location reveal regions of greater and lesser recombination, as well as regions exhibiting significant segregation distortion. The work presented here has led to a greatly improved ordering of the potato reference genome superscaffolds into chromosomal "pseudomolecules".