RESUMEN
The interactions between aphids and their host plants seem to be analogous to those of plant-microbial pathogens. Unlike microbial pathogen effectors, little is known about aphid effectors and their ability to interfere with host immunity. To date, only three functional aphid effectors have been reported. To identify potato aphid (Macrosiphum euphorbiae) effectors, we developed a salivary gland transcriptome using Illumina technology. We generated 85 million Illumina reads from salivary glands and assembled them into 646 contigs. Ab initio sequence analysis predicted secretion signal peptides in 24% of these sequences, suggesting that they might be secreted into the plant during aphid feeding. Eight of these candidate effectors with secretion signal peptides were functionally characterized using Agrobacterium tumefaciens-mediated transient overexpression in Nicotiana benthamiana. Two candidate effectors, Me10 and Me23, increased aphid fecundity, suggesting their ability to suppress N. benthamiana defenses. Five of these candidate effectors, including Me10 and Me23, were also analyzed in tomato by delivering them through the Pseudomonas syringae type three secretion system. In tomato, only Me10 increased aphid fecundity. This work identified two additional aphid effectors with ability to manipulate the host for their advantage.
Asunto(s)
Áfidos/genética , Regulación de la Expresión Génica/genética , Proteínas de Insectos/metabolismo , Enfermedades de las Plantas/parasitología , Solanum tuberosum/parasitología , Transcriptoma , Secuencia de Aminoácidos , Animales , Áfidos/fisiología , Bioensayo , Secuencia Conservada , Fertilidad , Biblioteca de Genes , Secuenciación de Nucleótidos de Alto Rendimiento , Interacciones Huésped-Parásitos , Proteínas de Insectos/química , Proteínas de Insectos/genética , Solanum lycopersicum/parasitología , Datos de Secuencia Molecular , Ninfa , Especificidad de Órganos , Señales de Clasificación de Proteína , Pseudomonas syringae/genética , Glándulas Salivales/metabolismo , Alineación de Secuencia , Nicotiana/parasitologíaRESUMEN
Many coleus (Solenostemon scutellarioides (L). Codd) varieties change pigmentation when exposed to high light intensity: they increase anthocyanin amount and decrease chlorophyll content. The physiological and molecular mechanisms involved in this phenomenon have been investigated in two independent experiments using two related coleus varieties 'Royal Glissade' (RG) and 'UF06-1-06' (UF). The developmental stage of a leaf had a minimum effect on colouration. Light intensity affected the rate of colour transition, anthocyanin and chlorophyll concentrations, and plant growth. Foliage colour was affected by a complex interaction between anthocyanin and chlorophyll. The isolation and expression analysis of several structural and regulatory genes involved in the anthocyanin biosynthetic pathway, and the genes Lchb2 and CBS, an indicator of cellular energy status are reported. Results indicate a close similarity between transcript amount and anthocyanin accumulation and its rate was tightly associated with light intensity. Differences in foliage colour between RG and UF are due to different sensitivity to light, probably affecting chlorophyll content and F3H and UFGT expression.
Asunto(s)
Coleus/metabolismo , Luz , Pigmentación/efectos de la radiación , Pigmentos Biológicos/metabolismo , Hojas de la Planta/metabolismo , Antocianinas/metabolismo , Biomasa , Clorofila/metabolismo , Coleus/genética , Coleus/crecimiento & desarrollo , Colorimetría/métodos , Relación Dosis-Respuesta en la Radiación , Regulación del Desarrollo de la Expresión Génica/efectos de la radiación , Regulación de la Expresión Génica de las Plantas/efectos de la radiación , Hojas de la Planta/genética , Hojas de la Planta/crecimiento & desarrollo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
The unique flavour of a tomato fruit is the sum of a complex interaction among sugars, acids, and a large set of volatile compounds. While it is generally acknowledged that the flavour of commercially produced tomatoes is inferior, the biochemical and genetic complexity of the trait has made breeding for improved flavour extremely difficult. The volatiles, in particular, present a major challenge for flavour improvement, being generated from a diverse set of lipid, amino acid, and carotenoid precursors. Very few genes controlling their biosynthesis have been identified. New quantitative trait loci (QTLs) that affect the volatile emissions of red-ripe fruits are described here. A population of introgression lines derived from a cross between the cultivated tomato Solanum lycopersicum and its wild relative, S. habrochaites, was characterized over multiple seasons and locations. A total of 30 QTLs affecting the emission of one or more volatiles were mapped. The data from this mapping project, combined with previously collected data on an IL population derived from a cross between S. lycopersicum and S. pennellii populations, were used to construct a correlational database. A metabolite tree derived from these data provides new insights into the pathways for the synthesis of several of these volatiles. One QTL is a novel locus affecting fruit carotenoid content on chromosome 2. Volatile emissions from this and other lines indicate that the linear and cyclic apocarotenoid volatiles are probably derived from separate carotenoid pools.
Asunto(s)
Frutas/química , Sitios de Carácter Cuantitativo , Solanum lycopersicum/química , Carotenoides/genética , Carotenoides/metabolismo , Frutas/genética , Frutas/metabolismo , Solanum lycopersicum/clasificación , Solanum lycopersicum/genética , Solanum lycopersicum/metabolismo , Filogenia , Gusto , VolatilizaciónRESUMEN
Fruit ripening in tomato requires the coordination of both developmental cues and the phytohormone ethylene. The multigene ethylene receptor family has been shown to negatively regulate ethylene signal transduction and suppress ethylene responses. Here we demonstrate that reduction in the levels of either of two family members, LeETR4 or LeETR6, causes an early-ripening phenotype. We provide evidence that the receptors are rapidly degraded in the presence of ethylene, and that degradation probably occurs through the 26S proteasome-dependent pathway. Ethylene exposure of immature fruits causes a reduction in the amount of receptor protein and earlier ripening. The results are consistent with a model in which receptor levels modulate timing of the onset of fruit ripening by measuring cumulative ethylene exposure.
Asunto(s)
Etilenos/metabolismo , Frutas/metabolismo , Proteínas de Plantas/metabolismo , Receptores de Superficie Celular/metabolismo , Solanum lycopersicum/metabolismo , Frutas/crecimiento & desarrollo , Regulación de la Expresión Génica de las Plantas , Solanum lycopersicum/crecimiento & desarrollo , Familia de Multigenes , Complejo de la Endopetidasa Proteasomal/metabolismo , ARN sin Sentido , Factores de TiempoRESUMEN
Abscission was studied in immature apple fruits (cv. Golden Delicious) during the physiological drop. Fruitlet populations, characterized by different abscission potential, were analysed. Non-abscising fruitlets (NAF) were obtained from central flowers borne in clusters where all the lateral flowers had been removed at bloom while abscising fruitlets (AF) were derived from lateral fruitlets of trees sprayed with benzylaminopurine (BAP) at 200 ppm, 17 d after petal fall (APF), when the fruit cross diameter was about 10-12 mm. Fruit shedding, monitored at the end of the June drop, was significantly different in the two populations, being less than 10%, and more than 90%, in NAF and AF, respectively. In AF, fruit drop peaked around 33 d after petal fall (APF) and was preceded by an increase in ethylene around 20 d APF. Transcript analysis was performed from 17-24 d APF, since preliminary experiments pointed out that major changes in expression of abscission related genes occurred within this period. Transcript accumulation of genes involved in ethylene biosynthesis (MdACS5B and MdACO) and action (MdERS1, MdETR1, and MdCTR1) was studied in the seed, cortex, peduncle, and abscission zone (AZ) of the two fruit populations. MdACS5B and MdACO transcripts accumulated along the experimental period in AF population, even though at a different magnitude, while ethylene evolution declined after peaking at day three. MdETR1, MdERS1, and MdCTR1 expression patterns depended on tissue and/or population. The ERS/ETR ratio was higher in AF than in NAF populations. Overall results pointed out that apple fruitlet drop is preceded by a stimulation of ethylene biosynthesis and a gain in sensitivity to the hormone.