RESUMO
Strigolactones (SLs), a class of carotenoid-derived hormones, play a crucial role in flowering plants by regulating underground communication with symbiotic arbuscular mycorrhizal fungi (AM) and controlling shoot and root architecture. While the functions of core SL genes have been characterized in many plants, their roles in non-tracheophyte plants like liverworts require further investigation. In this study, we employed the model liverwort species Marchantia polymorpha, which lacks detectable SL production and orthologs of key SL biosynthetic genes, including CAROTENOID CLEAVAGE DIOXYGENASE 8 (CCD8) and MORE AXILLARY GROWTH 1 (MAX1). However, it retains some SL pathway components, including DWARF27 (D27) and CCD7. To help elucidate the function of these remaining components in M. polymorpha, knockout mutants were generated for MpD27-1, MpD27-2 and MpCCD7. Phenotypic comparisons of these mutants with the wild-type control revealed a novel role for these genes in regulating the release of gemmae from the gemma cup and the germination and growth of gemmae in the dark. Mpd27-1, Mpd27-2, and Mpccd7 mutants showed lower transcript abundance of genes involved in photosynthesis, such as EARLY LIGHT INDUCED (ELI), and stress responses such as LATE EMBRYOGENESIS ABUNDANT (LEA) but exhibited higher transcript levels of ETHYLENE RESPONSE FACTORS (ERFs) and SL and carotenoid related genes, such as TERPENE SYNTHASE (TS), CCD7 and LECITHIN-RETINAL ACYL TRANSFERASE (LRAT). Furthermore, the mutants of M. polymorpha in the SL pathway exhibited increased contents of carotenoid. This unveils a previously unrecognized role for MpD27-1, MpD27-2 and MpCCD7 in controlling release, germination, and growth of gemmae in response to varying light conditions. These discoveries enhance our comprehension of the regulatory functions of SL biosynthesis genes in non-flowering plants.
RESUMO
In the early 1900s, Erwin Baur established Antirrhinum majus as a model system, identifying and characterising numerous flower colour variants. This included Picturatum/Eluta, which restricts the accumulation of magenta anthocyanin pigments, forming bullseye markings on the flower face. We identified the gene underlying the Eluta locus by transposon-tagging, using an Antirrhinum line that spontaneously lost the nonsuppressive el phenotype. A candidate MYB repressor gene at this locus contained a CACTA transposable element. We subsequently identified plants where this element excised, reverting to a suppressive Eluta phenotype. El alleles inhibit expression of anthocyanin biosynthetic genes, confirming it to be a regulatory locus. The modes of action of Eluta were investigated by generating stable transgenic tobacco lines, biolistic transformation of Antirrhinum petals and promoter activation/repression assays. Eluta competes with MYB activators for promoter cis-elements, and also by titrating essential cofactors (bHLH proteins) to reduce transcription of target genes. Eluta restricts the pigmentation established by the R2R3-MYB factors, Rosea and Venosa, with the greatest repression on those parts of the petals where Eluta is most highly expressed. Baur questioned the origin of heredity units determining flower colour variation in cultivated A. majus. Our findings support introgression from wild species into cultivated varieties.
Assuntos
Antocianinas , Antirrhinum , Flores , Regulação da Expressão Gênica de Plantas , Fenótipo , Pigmentação , Proteínas de Plantas , Antirrhinum/genética , Flores/genética , Flores/fisiologia , Pigmentação/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Antocianinas/metabolismo , Plantas Geneticamente Modificadas , Genes de Plantas , Nicotiana/genética , Regiões Promotoras Genéticas/genética , Elementos de DNA Transponíveis/genética , AlelosRESUMO
Floral nectar composition beyond common sugars shows great diversity but contributing genetic factors are generally unknown. Manuka (Leptospermum scoparium) is renowned for the antimicrobial compound methylglyoxal in its derived honey, which originates from the precursor, dihydroxyacetone (DHA), accumulating in the nectar. Although this nectar trait is highly variable, genetic contribution to the trait is unclear. Therefore, we investigated key gene(s) and genomic regions underpinning this trait. We used RNAseq analysis to identify nectary-associated genes differentially expressed between high and low nectar DHA genotypes. We also used a manuka high-density linkage map and quantitative trait loci (QTL) mapping population, supported by an improved genome assembly, to reveal genetic regions associated with nectar DHA content. Expression and QTL analyses both pointed to the involvement of a phosphatase gene, LsSgpp2. The expression pattern of LsSgpp2 correlated with nectar DHA accumulation, and it co-located with a QTL on chromosome 4. The identification of three QTLs, some of the first reported for a plant nectar trait, indicates polygenic control of DHA content. We have established plant genetics as a key influence on DHA accumulation. The data suggest the hypothesis of LsSGPP2 releasing DHA from DHA-phosphate and variability in LsSgpp2 gene expression contributing to the trait variability.
Assuntos
Di-Hidroxiacetona , Regulação da Expressão Gênica de Plantas , Leptospermum , Néctar de Plantas , Locos de Características Quantitativas , Locos de Características Quantitativas/genética , Néctar de Plantas/metabolismo , Di-Hidroxiacetona/metabolismo , Leptospermum/metabolismo , Monoéster Fosfórico Hidrolases/genética , Monoéster Fosfórico Hidrolases/metabolismo , Genes de Plantas , Genótipo , Mapeamento Cromossômico , Cromossomos de Plantas/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMO
En el último tiempo se ha incrementado la detección de nódulos pulmonares, debido al uso de la tomografía computada multicorte (TCMC) y a la implementación de métodos de cribado de cáncer de pulmón mediante el uso de la tomografía computada (TC) de baja dosis. Esto ha despertado especial interés en los nódulos de tipo subsólido por su probabilidad de tener una etiología maligna, en particular el adenocarcinoma (ADC). Con el análisis minucioso de las imágenes adquiridas en la tomografía computada multicorte se pueden identificar las características morfológicas de cada nódulo y realizar una correlación en forma aproximada con su probable anatomía patológica. La evaluación, junto con el contexto clínico-epidemiológico del paciente, hace posible un diagnóstico presuntivo y un pronóstico aproximado, permitiendo determinar las conductas terapéuticas o los planes de seguimiento...