ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Fruit-dependent epigenetic regulation of flowering in Citrus
Get PDFIn many perennial plants, seasonal flowering is primarily controlled by environmental conditions, but in certain polycarpic plants, environmental signals are locally gated by the presence of developing fruits initiated in the previous season through an unknown mechanism. Polycarpy is defined as the ability of plants to undergo several rounds of reproduction during their lifetime, alternating vegetative and reproductive meristems in the same individual. To understand how fruits regulate flowering in polycarpic plants, we focused on alternate bearing in Citrus trees that had been experimentally established as fully flowering or nonflowering. We found that the presence of the fruit causes epigenetic changes correlating with the induction of the CcMADS19 floral repressor, which prevents the activation of the floral promoter CiFT2 even in the presence of the floral inductive signals. By contrast, newly emerging shoots display an opposite epigenetic scenario associated with CcMADS19 repression, thereby allowing the activation of CiFT2 the following cold season
A cross population between D. kaki and D. virginiana shows high variability for saline tolerance and improved salt stress tolerance
Get PDFPersimmon (Diospyros kaki Thunb.) production is facing important problems related to climate change in the Mediterranean areas. One of them is soil salinization caused by the decrease and change of the rainfall distribution. In this context, there is a need to develop cultivars adapted to the increasingly challenging soil conditions. In this study, a backcross
between (D. kaki x D. virginiana) x D. kaki was conducted, to unravel the mechanism involved in salinity tolerance of persimmon. The backcross involved the two species most used as rootstock for persimmon production. Both species are clearly distinct in their level of tolerance to salinity. Variables related to growth, leaf gas exchange, leaf water relations and content of nutrients were significantly affected by saline stress in the backcross population.
Water flow regulation appears as a mechanism of salt tolerance in persimmon via differences in water potential and transpiration rate, which reduces ion entrance in the plant. Genetic expression of eight putative orthologous genes involved in different mechanisms leading to salt tolerance was analyzed. Differences in expression levels among populations
under saline or control treatment were found. The ‘High affinity potassium transporter’ (HKT1-like) reduced its expression levels in the roots in all studied populations. Results obtained allowed selection of tolerant rootstocks genotypes and describe the hypothesis about the mechanisms involved in salt tolerance in persimmon that will be useful for breeding salinity tolerant rootstock
Genetic Variation in the Feeding Behavior of Isofemale Lines of Nesidiocoris tenuis
Get PDFZoophytophagous predators provide biocontrol services in various major crops of modern horticulture due to the combination of its predatory capacity and the induction of plant defenses derived from its phytophagy. However, under certain conditions of prey scarcity, these natural enemies can inflict plant damage. Exploitation of genetic variation and subsequent selective breeding on foraging traits is a potential alternative to overcome this inconvenience. In this study, we quantified the genetic variation of phytophagy and zoophagy of Nesidiocoristenuis (Reuter) (Hemiptera: Miridae), a zoophytophagous predator widely used in tomato crops to suppress key pests. We compared nine isofemale lines on their capacity to produce necrotic rings and wilting on tomato plants as a proxy for phytophagy, as well as their efficacy to prey on Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs, as a proxy for zoophagy. Differences between isofemale lines in phytophagy and zoophagy indicated a genetic basis. Variation found in the zoophagy levels was larger than that in phytophagy levels. Our results showed that there is a genetic basis for the variation observed in the feeding behavior of isofemale lines of N.tenuis, highlighting the potential importance of selective breeding for such traits of biocontrol interes
Biological Control Potential and Drawbacks of Three Zoophytophagous Mirid Predators against Bemisia tabaci in the United States
Get PDFMiridae (Hemiptera) of the tribe Dicyphini are important zoophytophagous predators use
to control pest arthropods in vegetable crops. However, the risk that their herbivory may cause
economic damage could hinder their application as useful biocontrol agents and may limit the
likelihood they would meet regulatory requirements for importation. We conducted field cage studies
to assess the predation capacity and tomato plant damage of three mirid species established in south
USA, a known biocontrol agent (Nesidiocoris tenuis), and two native species (Macrolophus praeclarus
and Engytatus modestus). All three species significantly reduced the number of whiteflies (Bemisia
tabaci) on tomato plants compared to tomato plants without mirids. More damage, evaluated as the
number of necrotic rings, was observed on tomato plants with E. modestus and N. tenuis compared to
M. praeclarus. In our experiments that included sesame plants (Sesamum indicum) with tomato plants,
mirid numbers increased despite a low number of prey, thus showing a benefit of the plant-feeding
habit of these predators. USA’s established mirids may therefore prove to be immediately available
biological agents for the management of present and future tomato pests
Field Comparison of Electrical Resistance, Electromagnetic Induction, and Frequency Domain Reflectometry for Soil Salinity Appraisal
Get PDFBy using different physical foundations and technologies, many probes have been developed for on-site soil salinity appraisal in the last forty years. In order to better understand their respective technical and practical advantages and constraints, comparisons among probes are needed. In this study, three different probes, based on electrical resistance (ER), electromagnetic induction (EMI), and frequency domain reflectometry (FDR), were compared during a field survey carried out in a large salt-threatened agricultural area. Information about the soil bulk electrical conductivity (σb) at different depths was obtained with each of the probes and, additionally, other soil properties were also measured depending on the specifications of each instrument and, moreover, determined in samples. On average, the EMI and FDR techniques could be regarded as equivalent for σb measurement, whereas ER gave higher σb values. Whatever the case, EMI, and also ER, had to be supplemented with information about soil clay, organic matter, and water mass fractions to attain, despite this effort, poor soil salinity estimations by means of multiple linear regression models (R2 < 0.5). On the contrary, FDR needed only probe data to achieve R2 of 0.7, though root mean standard error (RMSE) was still 1.5 dS m−1. The extra measurements and calculations that modern electrical conductivity contact probes integrate, specifically, those based on FDR, remarkably increase their ability for soil salinity appraisal, although there is still room for improvement
Geographically distant isolates of the persistent southern tomato virus (STV) show very low genetic diversity in the putative coat protein gene
Get PDFSouthern tomato virus (STV) from genus Amalgavirus (Family Amalgaviridae) is a persistent virus infecting tomato crops
worldwide. Information on genetic diversity and evolutionary mechanisms for plant persistent viruses are very scarce in
comparison with plant acute viruses. In this work, the putative coat protein gene of worldwide STV isolates was analyzed
showing very low nucleotide diversity (< 0.0100). Phylogenetic analysis separated STV isolates into two clades, but no
correlation was found between genetic and geographic distances. Also, no recombination events among STV isolates were
detected. Comparison of synonymous and nonsynonymous substitutions indicated negative selection at the amino acid level
Evidence of the Role of QTL Epistatic Interactions in the Increase of Melon Fruit Flesh Content during Domestication
Get PDFCultivated melon was domesticated from wild melons, which produce small fruits with
non-edible fruit flesh. The increase in fruit flesh is one of the major domestication achievements in
this species. In previous work, a quantitative trait locus (QTL) on chromosome 6 (paqt6.1) linked to
fruit flesh content was detected in a cross between cultivated (“Piel de Sapo”, PS) and wild (Ames
24294, TRI) accessions. The QTL was introgressed into the PS background, generating the TRI_6-3
introgression line (IL) that confirmed the e ects of paqt6.1. The primary objective of this work was to
fine-map paqt6.1 as the first step for the map-based cloning. Two di erent approaches were carried
out; however, the results were not consistent, precluding the fine mapping of paqt6.1. TRI_6-3 and
other related ILs were genotyped by genotyping-by-sequencing, finding additional introgressions
in other chromosomes. In an F2 population from TRI_6-3-x-PS, we found an epistatic interaction
between paqt6.1 and another locus on chromosome 11. The interaction was verified in advanced
populations, suggesting that the e ects of paqt6.1 are conditioned by the allelic composition at another
locus in chromosome 11. Both loci should have TRI alleles to reduce the flesh content in the PS
background. The implications on the history of melon domestication are discussed
The effect of stress on reproduction and reproductive technologies in beef cattle—A review
Get PDFResearchers have contributed by increasing our understanding of the factors affecting reproduction in beef, mainly physical health and nutrition aspects, which have been main concerns during decades. Animal welfare is of outmost relevance in all animal production systems and it is strongly associated to stress. Stress responses involve endocrine, paracrine and neural systems and the consequences of this stress on the reproductive efficiency of specifically, beef cattle and bulls, need to be highlighted. We, therefore, describe the fundamentals of stress and its quantification, focusing in beef herds, reviewing the highly valuable pieces of research, already implemented in this field. We examine major factors (stressors) contributing to stress in beef cattle and their effects on the animals, their reproductive performance and the success of reproductive biotechnologies. We include terms such as acclimatization, acclimation or temperament, very relevant in beef systems. We examine specifically the management stress due to handling, social environment and hierarchy or weaning effects; nutritional stress; and thermal stress (not only heat stress) and also review the influence of these stressors on reproductive performance and effectiveness of reproductive biotechnologies in beef herds. A final message on the attention that should be devoted to these factors is highlighted
Assessment of Multilocus Sequence Analysis (MLSA) for Identification of Candidatus Liberibacter Solanacearum from Different Host Plants in Spain
Get PDFLiberibacter is a bacterial group causing different diseases and disorders in plants. Among liberibacters, Candidatus Liberibacter solanaceraum (CLso) produces disorders in several species mainly within Apiaceae and Solanaceae families. CLso isolates are usually grouped in defined haplotypes according to single nucleotide polymorphisms in genes associated with ribosomal elements. In order to characterize more precisely isolates of CLso identified in potato in Spain, a Multilocus Sequence Analysis (MLSA) was applied. This methodology was validated by a complete analysis of ten housekeeping genes that showed an absence of positive selection and a nearly neutral mechanism for their evolution. Most of the analysis performed with single housekeeping genes, as well as MLSA, grouped together isolates of CLso detected in potato crops in Spain within the haplotype E, undistinguishable from those infecting carrots, parsnips or celery. Moreover, the information from these housekeeping genes was used to estimate the evolutionary divergence among the different CLso by using the concatenated sequences of the genes assayed. Data obtained on the divergence among CLso haplotypes support the hypothesis of evolutionary events connected with different hosts, in different geographic areas, and possibly associated with different vectors. Our results demonstrate the absence in Spain of CLso isolates molecularly classified as haplotypes A and B, traditionally considered causal agents of zebra chip in potato, as well as the uncertain possibility of the present haplotype to produce major disease outbreaks in potato that may depend on many factors that should be further evaluated in future works
