RESUMO
BACKGROUND: Paspalum dilatatum Poir. (common name dallisgrass) is a native grass species of South America, with special relevance to dairy and red meat production. P. dilatatum exhibits higher forage quality than other C4 forage grasses and is tolerant to frost and water stress. This species is predominantly cultivated in an apomictic monoculture, with an inherent high risk that biotic and abiotic stresses could potentially devastate productivity. Therefore, advanced breeding strategies that characterise and use available genetic diversity, or assess germplasm collections effectively are required to deliver advanced cultivars for production systems. However, there are limited genomic resources available for this forage grass species. RESULTS: Transcriptome sequencing using second-generation sequencing platforms has been employed using pooled RNA from different tissues (stems, roots, leaves and inflorescences) at the final reproductive stage of P. dilatatum cultivar Primo. A total of 324,695 sequence reads were obtained, corresponding to c. 102 Mbp. The sequences were assembled, generating 20,169 contigs of a combined length of 9,336,138 nucleotides. The contigs were BLAST analysed against the fully sequenced grass species of Oryza sativa subsp. japonica, Brachypodium distachyon, the closely related Sorghum bicolor and foxtail millet (Setaria italica) genomes as well as against the UniRef 90 protein database allowing a comprehensive gene ontology analysis to be performed. The contigs generated from the transcript sequencing were also analysed for the presence of simple sequence repeats (SSRs). A total of 2,339 SSR motifs were identified within 1,989 contigs and corresponding primer pairs were designed. Empirical validation of a cohort of 96 SSRs was performed, with 34% being polymorphic between sexual and apomictic biotypes. CONCLUSIONS: The development of genetic and genomic resources for P. dilatatum will contribute to gene discovery and expression studies. Association of gene function with agronomic traits will significantly enable molecular breeding and advance germplasm enhancement.
Assuntos
Estudos de Associação Genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Paspalum/genética , Mapeamento de Sequências Contíguas , Etiquetas de Sequências Expressas , Ontologia Genética , Marcadores Genéticos , Genoma de Planta/genética , Repetições de Microssatélites/genética , Anotação de Sequência Molecular , Motivos de Nucleotídeos/genética , Polimorfismo Genético , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Reprodutibilidade dos TestesRESUMO
Chrysanthemums (Chrysanthemum×morifolium Ramat.) are an important cut-flower and potted plant crop in the horticultural industry world wide. Chrysanthemums express the flavonoid 3'-hydroxylase (F3'H) gene and thus accumulate anthocyanins derived from cyanidin in their inflorescences which appear pink/red. Delphinidin-based anthocyanins are lacking due to the deficiency of a flavonoid 3', 5'-hydroxylase (F3'5'H), and so violet/blue chrysanthemum flower colors are not found. In this study, together with optimization of transgene expression and selection of the host cultivars and gene source, F3'5'H genes have been successfully utilized to produce transgenic bluish chrysanthemums that accumulate delphinidin-based anthocyanins. HPLC analysis and feeding experiments with a delphinidin precursor identified 16 cultivars of chrysanthemums out of 75 that were predicted to turn bluish upon delphinidin accumulation. A selection of eight cultivars were successfully transformed with F3'5'H genes under the control of different promoters. A pansy F3'5'H gene under the control of a chalcone synthase promoter fragment from rose resulted in the effective diversion of the anthocyanin pathway to produce delphinidin in transgenic chrysanthemum flower petals. The resultant petal color was bluish, with 40% of total anthocyanidins attributed to delphinidin. Increased delphinidin levels (up to 80%) were further achieved by hairpin RNA interference-mediated silencing of the endogenous F3'H gene. The resulting petal colors were novel bluish hues, not possible by hybridization breeding. This is the first report of the production of anthocyanins derived from delphinidin in chrysanthemum petals leading to novel flower color.
Assuntos
Antocianinas/biossíntese , Chrysanthemum/genética , Flores/genética , Engenharia Metabólica/métodos , Pigmentação/genética , Aciltransferases/genética , Antocianinas/análise , Vias Biossintéticas/genética , Cromatografia Líquida de Alta Pressão , Chrysanthemum/metabolismo , Cor , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Flores/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genética , Reprodutibilidade dos Testes , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Although phosphorus is an essential factor for proper plant growth in natural environments, an excess of phosphate in water sources causes serious pollution. In this paper we describe transgenic plants which hyperaccumulate inorganic phosphate (Pi) and which may be used to reduce environmental water pollution by phytoremediation. AtPHR1, a transcription factor for a key regulator of the Pi starvation response in Arabidopsis thaliana, was overexpressed in the ornamental garden plants Torenia, Petunia, and Verbena. The transgenic plants showed hyperaccumulation of Pi in leaves and accelerated Pi absorption rates from hydroponic solutions. Large-scale hydroponic experiments indicated that the enhanced ability to absorb Pi in transgenic torenia (AtPHR1) was comparable to water hyacinth a plant that though is used for phytoremediation causes overgrowth problems.
Assuntos
Engenharia Genética , Lamiaceae/metabolismo , Petunia/metabolismo , Fosfatos/metabolismo , Verbena/metabolismo , Absorção , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Biodegradação Ambiental , Hidroponia , Lamiaceae/genética , Petunia/genética , Fósforo/metabolismo , Plantas Geneticamente Modificadas , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Verbena/genéticaRESUMO
Flower color is mainly determined by anthocyanins. Rosa hybrida lacks violet to blue flower varieties due to the absence of delphinidin-based anthocyanins, usually the major constituents of violet and blue flowers, because roses do not possess flavonoid 3',5'-hydoxylase (F3'5'H), a key enzyme for delphinidin biosynthesis. Other factors such as the presence of co-pigments and the vacuolar pH also affect flower color. We analyzed the flavonoid composition of hundreds of rose cultivars and measured the pH of their petal juice in order to select hosts of genetic transformation that would be suitable for the exclusive accumulation of delphinidin and the resulting color change toward blue. Expression of the viola F3'5'H gene in some of the selected cultivars resulted in the accumulation of a high percentage of delphinidin (up to 95%) and a novel bluish flower color. For more exclusive and dominant accumulation of delphinidin irrespective of the hosts, we down-regulated the endogenous dihydroflavonol 4-reductase (DFR) gene and overexpressed the Irisxhollandica DFR gene in addition to the viola F3'5'H gene in a rose cultivar. The resultant roses exclusively accumulated delphinidin in the petals, and the flowers had blue hues not achieved by hybridization breeding. Moreover, the ability for exclusive accumulation of delphinidin was inherited by the next generations.
