ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Intra and Inter-specific Variability of Salt Tolerance Mechanisms in Diospyros Genus
Get PDFSaline stress is one of most important problems that agriculture must face in the context of climate change. In the Mediterranean basin, one of the regions most affected, persimmon production can be compromised by this effect, due to the limited availability of salt tolerant rootstocks. Seedlings coming from four populations from the Diospyros genus have been exposed to salt stress in order to identify salt tolerance genotypes within these
populations. Morphological, physiological, and transcriptomic approaches have revealed different mechanisms of tolerance among the population studied. An HKT1-like gene has been shown to have different root expression related to the salt tolerance
phenotypes among and within populations. Additionally, we have observed differences in
salt-responsive expression among PIP aquaporin genes. Genetic variability for salt tolerance can be generated in Diospyros species through crossings and used for overcome salt stress. Furthermore, differences in water use efficiency (WUE) have been
obtained between and within populations. The information gathered at transcriptomic and
physiological level demonstrated natural and heritable variability among Diospyros genus which is the key for salt-tolerant rootstock breeding programs
Fast and Slow-Growing Management Systems: Characterisation of Broiler Caecal Microbiota Development throughout the Growing Period
Get PDFCaecal microbiota and its modulation play an important role in poultry health, productivity
and disease control. Moreover, due to the emergence of antimicrobial-resistant bacteria, society is
pressing for a reduction in antibiotic administration by finding e ective alternatives at farm level,
such as less intensified production systems. Hence, the aim of this study was to characterise the
caecal microbiota in two di erent broiler management systems, fast and slow-growing, using 16S
rRNA sequencing analysis. To this end 576 broilers were reared in two di erent management systems
(fast and slow-growing). Results showed that Firmicutes represented the dominant phylum for both
systems. At the onset, Proteobacteria was the second prevalent phylum for fast and slow-growing
breeds, outnumbering the Bacteroidetes. However, during the rest of the production cycle, Bacteroidetes
was more abundant than Proteobacteria in both groups. Finally, regardless of the management system,
the most predominant genera identified were Oscillospira spp., Ruminococcus spp., Coprococcus spp.,
Lactobacillus spp. and Bacteroides spp. In conclusion, fast and slow-growing broiler microbiota are in
constant development throughout rearing, being relatively stable at 21 days of age. Regarding the
genus, it should be noted that the three most abundant groups for both systems, Ruminococcus spp.,
Lactobacillus spp. and Bacteroides spp., are related to better productive performance and intestinal health
Adaptation to Water and Salt Stresses of Solanum pimpinellifolium and Solanum lycopersicum var. cerasiforme
Get PDFSolanum pimpinellifolium and Solanum lycopersicum var. cerasiforme represent a valuable tool for tomato breeding, particularly for tolerance to abiotic stresses. Water stress and salinity are major constraints to tomato’s cultivation, and for which limited genetic variability has been reported within the cultivated species. We evaluated four accessions of S. pimpinellifolium and four of S. l. var. cerasiforme for their adaptation to water deficit and salinity. The CO2 assimilation rate, stomatal conductance, substomatal CO2 concentration, transpiration rate, and leaf chlorophyll concentration were evaluated, as well as morphological and agronomic traits. The accessions showed a remarkable inter- and intra-species response variability to both stresses. Two S. pimpinellifolium accessions and one S. l. var. cerasiforme showed unaltered physiological parameters, thus indicating a good adaptation to water deficit. Two S. l. var. cerasiforme accessions showed an interesting performance under salt stress, one of which showing also good adaptation to water stress. In general, both stresses showed a negative impact on leaf size and fruit fresh weight, especially in the big-sized fruits. However, flowering, fruit setting and earliness remained unaltered or even improved when compared to control conditions. Stressed plants yielded fruits with higher ° Brix. Response to stresses seemed to be linked to origin environmental conditions, notwithstanding, variability was observed among accessions of the same region
Main Root Adaptations in Pepper Germplasm (Capsicum spp.) to Phosphorus Low-Input Conditions
Get PDFAgriculture will face many challenges regarding food security and sustainability. Improving phosphorus use efficiency is of paramount importance to face the needs of a growing population while decreasing the toll on the environment. Pepper (Capsicum spp.) is widely cultivated around the world; hence, any breakthrough in this field would have a major impact in agricultural systems. Herein, the response to phosphorus low-input conditions is reported for 25 pepper accessions regarding phosphorus use efficiency, biomass and root traits. Results suggest a differential response from different plant organs to phosphorus starvation. Roots presented the lowest phosphorus levels, possibly due to mobilizations towards above-ground organs. Accessions showed a wide range of variability regarding efficiency parameters, offering the possibility of selecting materials for different inputs. Accessions bol_144 and fra_DLL showed an interesting phosphorus efficiency ratio under low-input conditions, whereas mex_scm and sp_piq showed high phosphorus uptake efficiency and mex_pas and sp_bola the highest values for phosphorus use efficiency. Phosphorus low-input conditions favored root instead of aerial growth, enabling increases of root total length, proportion of root length dedicated to fine roots and root specific length while decreasing roots’ average diameter. Positive correlation was found between fine roots and phosphorus efficiency parameters, reinforcing the importance of this adaptation to biomass yield under low-input conditions. This work provides relevant first insights into pepper’s response to phosphorus low-input conditions
Non-stationary spatial model for the distribution of Xylella fastidiosa in Alicante
Get PDFDescribing the effect of climatic and spatial factors on the geographic distribution of the plant pathogenic bacterium Xylella fastidiosa has been the main aim since the moment that it was discovered its presence in Alicante (Spain). This work started with the analysis of the presence/absence data of the pathogen using Bayesian hierarchical models through the integrated nested Laplace approximation methodology and the stochastic partial differential equation approach. Spatial models usually assume stationarity, however, this may be not applicable when physical barriers are present in the study area. Taking into account the
irregularities of the terrain and what this may entail in the spread of the disease, higher altitude areas have been considered as possible barriers in the area of interest. The results show that the spatial effect had a strong effect in the model and also that there was no great influence of the barriers due to their reduced extension. Future work will be focused in using these barriers models
with theoretical phytosanitary barriers
La mecanización de los tratamientos fitosanitarios, la poda y la recolección Presente y futuro
Get PDFEl grado de mecanización de las labores agrícolas en la citricultura comparado con otros cultivos
como los extensivos, el olivo, el almendro y la vid es muy bajo y/o poco eficiente. Las principales
operaciones de cultivo son la poda, el control de plagas y enfermedades y la recolección, que en la
Comunitat Valenciana representan unos costes respectivos de entre el 11-14 %, el 15-20 %, y el
30-49 % respecto al total de los costes de cultivo, lo que en conjunto supone entre el 64 y el 75 %
de estos (Mateu et al., 2018a)
Alborea: A New Mid-late Mandarin Triploid Hybrid [(Citrus clementina x C. tangerina) x (C. nobilis x C. deliciosa)]
Get PDFCitrus is one of the most important fruit crops worldwide, with more than 130 million tons produced in 2017. Mandarins represent 25% of this production (Food and Agriculture Organization, 2018) and are mainly destined for fresh consumption. The Mediterranean area is the most important region for mandarin exports, with 60% of the total volume, and Spain is the leading country. The fresh market demands high-quality, seedless fruit that can be harvested throughout the marketing season. Therefore, mandarin breeding programs worldwide are mainly aimed at obtaining new, seedless, easy-peeling varieties with an attractive fruit color and flavor, and with high organoleptic characteristics (Grosser et al., 2010; Navarro et al., 2015; Rapisarda et al., 2008). The mandarin varietal structure in Spain has several problems. It includes satsumas [Citrus unshiu (Mak.) Marc.], clementines (C. clementina Hort. ex Tan.), and mandarin hybrids. Satsumas are harvested from the end of August to mid November. Their pollen and ovules are not viable, and thus they are seedless. Clementine varieties are the most important group of mandarins in Spain and can be harvested from mid September until the second half of January. They are self-incompatible, but their pollen and ovules are viable and, consequently, they are able to pollinate and be pollinated with other compatible cultivars. ‘Hernandina’ clementine, our latest maturing clementine, is characterized by low fruit quality when grafted onto ‘Carrizo’ citrange [C. sinensis (L.) Osbeck × Poncirus trifoliata (L.) Raf.], which is by far the predominant rootstock in our country. Fruit peel deteriorates quickly after mid January, and in practice no clementine fruit is available in the second half of January. Mandarin hybrids, such as ‘Nova’ [C. clementina × (C. paradisi Macf. × C. tangerina Hort. Ex Tan.)], ‘Fortune’ (C. clementina × ?), ‘Murcott’ (C. reticulata Blanco × C. sinensis), and ‘Ortanique’ (natural hybrid between mandarin and C. sinensis), were introduced to our citriculture to cover the demand of late-maturing mandarins by international markets. These cultivars are self-incompatible, but their pollen and ovules are viable and they cross-pollinate with clementines, producing seedy fruit in both groups of mandarins. In addition, some late mandarin hybrids, such as ‘Fortune’, ‘Nova’, and ‘Murcott’, are susceptible to Alternaria alternata fungus, which reduces production and depreciates the fruit commercially for the fresh-fruit market. This fungus has forced the top-grafting of trees of these susceptible cultivars, particularly ‘Fortune’, and during the past few decades there has been a decrease in late-mandarin plantations and an increase in clementine plantings, mainly ‘Clemenules’. This has created an imbalance between production and market demand that has caused a drastic reduction in prices for the growers such that, in many cases, they cannot even sell their products. As a consequence of excessive clementine production, a lot of growers decided to cultivate other late mandarin cultivars, especially ‘Nadorcott’ [(C. reticulata × C. sinensis) × ?], ‘Tango’ (irradiated variety from ‘Nadorcott’ mandarin), and ‘Orri’ (irradiated variety from ‘Orah’ mandarin) and, more recently, ‘Spring Sunshine’ (irradiated variety from ‘Murcott’ mandarin), which is susceptible to Alternaria. These varieties cover the period from February to the end of April and are managed by different private companies that limit the number of plants or the cultivated area, and also impose high royalties that, in many cases, are difficult for growers to pay. Under this scenario, the recovery of a new, high-quality seedless mandarin cultivar that matures from mid December until the end of January, when there are no other high-quality mandarins in the market, and that is resistant to Alternaria is a very important objective for our citriculture. In 1995, a triploid breeding program was started at the Instituto Valenciano de Investigaciones Agrarias (IVIA) with the objective of producing new mid- and late-maturing triploid cultivars resistant to A. alternata fungus through sexual hybridization, embryo rescue, and ploidy analysis by flow cytometry (Navarro et al., 2015). Triploid plants generally produce aneuploid gametes, thus leading to very low fertility of their pollen and ovules (Otto and Whitton, 2000). For this reason, citrus triploid hybrids can be considered sterile, producing seedless fruit, and do not induce seed formation in other varieties by cross-pollination, even in the presence of bees (Navarro et al., 2015). A routine strategy exploited for triploid citrus breeding is spontaneous female unreduced gamete formation in diploid × diploid crosses (Aleza et al., 2012; Cuenca et al., 2011, 2015), where triploid hybrids arise usually from the union of an unreduced megagametophyte formed through a second-division restitution mechanism with a haploid pollen (Cameron and Frost 1968; Cuenca et al., 2011; 2015; Esen and Soost 1971, 1973; Geraci et al., 1975; Luro et al., 2004). Triploid embryos are predominantly found in small seeds, which generally do not germinate in greenhouse conditions. Thus, embryo rescue from these small seeds is required to reach high germination rates (Aleza et al., 2010b). In addition, ploidy level determination by flow cytometry is also required in extensive triploid citrus breeding programs (Aleza et al., 2012). From this program, the mid- to late-maturing triploid varieties ‘Garbı’ [(C. clementina × C. tangerine) × (C. reticulata × C. sinensis)] (Aleza et al., 2010a) and ‘Safor’ [(C. clementina × C. tangerina) × (C. unshiu × C. nobilis Lour.)] (Cuenca et al., 2010) were released, with more than 600,000 plants commercialized until 2018.
We describe a new triploid hybrid named ‘Alborea’ mandarin [(C. clementina × C. tangerina) × (C. nobilis × C. deliciosa Ten.)] that is resistant to Alternaria alternata and characterized by the production of high-quality, seedless fruit that can be harvested from mid-December until the end of January
Disease Resistant Citrus Breeding Using Newly Developed High Resolution Melting and CAPS Protocols for Alternaria Brown Spot Marker Assisted Selection
Get PDFAlternaria alternata is a fungus that causes a serious disease in susceptible genotypes
of citrus, particularly in mandarins. The Alternaria citri toxin (ACT) produced by the pathogen
induces necrotic lesions on young leaves and fruits, defoliation and fruit drop. Here, we describe
two methods of marker-assisted selection (MAS) that could be used for the early identification of
Alternaria brown spot (ABS)-resistant mandarin hybrids. The first method is based on a nested PCR
coupled to high resolution melting (HRM) analysis at the SNP08 locus, which is located at 0.4 cM
from the ABS resistance locus, and was previously indicated as the most suitable for the selection of
ABS-resistant hybrids. The method was validated on 41 mandarin hybrids of the CREA germplasm
collection, and on 862 progenies generated from five crosses involving different susceptible parents.
Four out of five populations showed Mendelian segregation at the analyzed locus, while a population
involving Murcott tangor as male parent showed distorted segregation toward the susceptible hybrids.
The second method is based on a cleaved amplified polymorphic sequences (CAPS) marker that was
developed using the same primers as the nested PCR at the SNP08 locus, coupled with BccI restriction
enzyme digestion. To verify the reliability of the two genotyping methods, in vitro leaf phenotyping
was carried out by inoculating A. alternata spores onto young leaves of 101 hybrids, randomly chosen
among the susceptible and resistant progenies. The phenotyping confirmed the SNP08 genotyping
results, so the proposed method of selection based on HRM or CAPS genotyping could be routinely
used as an alternative to KBioscience competitive allele specific polymerase chain reaction (KASPar)
single nucleotide polymorphism (SNP) genotyping system to improve citrus breeding programs.
While the study confirmed that the SNP08 marker is a reliable tool for MAS of new citrus hybrids
with different genetic backgrounds, it also identified a small group of genotypes where the resistance
mechanism requires further investigation