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Acta Horticulturae
No full textThe availability of a saturated genetic map of Clementine was identified by the International Citrus Genome Consortium as an essential prerequisite to assist the assembly of the reference whole genome sequence based on a Clementine derived haploid. The primary goals of the present study were to establish a Clementine reference map, and to perform comparative mapping with pummelo and sweet orange. Five parental genetic maps were established with SNPs, SSRs and InDels. A medium density reference map (961 markers for 1084.1 cM) of Clementine was established and used by the ICGC to facilitate the chromosome assembly of the haploid genome sequence. Comparative mapping with pummelo and sweet orange revealed that the linear order of markers was highly conserved. Reasonable inferences of most citrus genomes should be obtained by mapping next-generation sequencing data against the haploid reference genome sequence. Skewed segregations were frequent and higher in the male than female Clementine potentially leading to false interpretation of the genetic determinism of phenotypic traits. The mapping data confirmed that Clementine arose from hybridization between 'Mediterranean' mandarin and sweet orange and identified nine recombination break points for the sweet orange gamete that contributed to the Clementine genome. Introgression of pummelo genome fragments were identified in heterozygosity in each chromosome. Moreover, it appeared that the genome of the haploid Clementine used to establish the citrus reference genome sequence was inherited primarily from the 'Mediterranean' mandarin. The usefulness of this genetic map, anchored in the reference whole genome sequence, is discussed
Involvement of a citrus meiotic recombination TTC-repeat motif in the formation of gross deletions generated by ionizing radiation and MULE activation
Get PDFBackground: Transposable-element mediated chromosomal rearrangements require the involvement of two transposons and two double-strand breaks (DSB) located in close proximity. In radiobiology, DSB proximity is also a major factor contributing to rearrangements. However, the whole issue of DSB proximity remains virtually unexplored. Results: Based on DNA sequencing analysis we show that the genomes of 2 derived mutations, Arrufatina (sport) and Nero (irradiation), share a similar 2 Mb deletion of chromosome 3. A 7 kb Mutator like element found in Clemenules was present in Arrufatina in inverted orientation flanking the 5' end of the deletion. The Arrufatina Mule displayed "dissimilar" 9-bp target site duplications separated by 2 Mb. Fine-scale single nucleotide variant analyses of the deleted fragments identified a TTC-repeat sequence motif located in the center of the deletion responsible of a meiotic crossover detected in the citrus reference genome. Conclusions: Taken together, this information is compatible with the proposal that in both mutants, the TTC-repeat motif formed a triplex DNA structure generating a loop that brought in close proximity the originally distinct reactive ends. In Arrufatina, the loop brought the Mule ends nearby the 2 distinct insertion target sites and the inverted insertion of the transposable element between these target sites provoked the release of the in-between fragment. This proposal requires the involvement of a unique transposon and sheds light on the unresolved question of how two distinct sites become located in close proximity. These observations confer a crucial role to the TTC-repeats in fundamental plant processes as meiotic recombination and chromosomal rearrangements
Hormonal Profile in Ovaries of Mandarin Varieties with Differing Reproductive Behaviour
No full textThe endogenous levels of 13 gibberellins (GAs), three cytokinins (CKs), abscisic acid (ABA), indole-3-acetic acid (IAA) and jasmonic acid (JA) were analyzed in naturally pollinated ovaries of three mandarin cultivars selected for their different capacity to produce seeds and their differing parthenocarpic ability. The varieties compared were Murcott (pollen self-compatible, highly seeded), Moncada (self-incompatible, moderately seeded), and Moncalina (pollen sterile, seedless), obtained from Moncada by bud γ-irradiation. As expected, the 13-hydroxylation pathway was predominant in ovaries and our results further indicate that cultivar differences exist in GA metabolism. The active gibberellin GA1 levels in ovaries seems to be related with presence of fertilized ovules and, therefore, with the ability to produce the seeds of a variety. Sterility gamma irradiation arrested the biosynthesis of GA1 and its precursor GA19 in Moncalina ovaries if compared to Moncada. The productive efficiency of the studied cultivars also indicated that fruit set depends strongly on the GA1 level achieved by ovaries, which is also closely related with carbohydrate content. The study of the expression of gibberellin-oxidase genes showed that the pollination/fecundation process enhances GA20ox2 and GA3ox1 activities in naturally pollinated Murcott and Moncada ovaries compared with unpollinated Murcott and Moncalina, respectively. GA2ox1 expression was lower in the ovaries of the highly seeded cultivar Murcott than in those of Moncada or Moncalina. Unpollinated Murcott ovaries contained much lower levels of GA1 and IAA than the naturally pollinated ovaries of this cultivar. Conversely, unpollinated ovaries, which exhibited 100 % abscission, had more ABA and JA contents. Cytokinin activity seemed constitutive and independent of pollination/fecundation. However, trans-zeatin (t-Z) and 2-isopentenyl adenine (2-IP) concentrations were higher in Murcott ovaries than in Moncada/Moncalina
Acta Horticulturae
No full textThis research work presents the development of a protocol for the micropropagation of three allotetraploid somatic hybrid rootstocks, obtained at IVIA from two hybridizations: Citrus macrophylla + citrange Carrizo and C. macrophylla + C. taiwanica. We have determined the conditions for the in vitro introduction and the establishment of micropropagation lines in the laboratory, with a high efficient multiplications rate of 3 every two weeks. The environmental conditions for the successful acclimatization and growth in the greenhouse have also been established. Finally, we have accomplished the large-scale adaptation for efficient commercial propagation
Effect of different superovulation stimulation protocols on adenosine triphosphate concentration in rabbit oocytes
No full textOvarian stimulation protocols are used usually to increase the number of oocytes collected. The determination of how oocyte quality may be affected by these superovulation procedures, therefore, would be very useful. There is a high correlation between oocyte ATP concentration and developmental competence of the resulting embryo. The aim of this study was to evaluate the effect of follicle stimulating hormone (FSH) origin and administration protocols on oocyte ATP content. Rabbit does were distributed randomly into four groups: (i) a control group; (ii) the rhFSH3 group: females were injected, every 24 h over 3 days, with 0.6 mu l of rhFSH diluted in polyvinylpyrrolidone (PVP); (iii) the pFSH3 group: females were injected every 24 h over 3 days with 11.4 mu g of pFSH diluted in PVP; and (iv) the pFSH5 group: females were injected twice a day for 5 days with 11.4 mu g of pFSH diluted in saline serum. Secondly, the effect of pFSH5 protocol on developmental potential was evaluated. Developmental competence of oocytes from the control and pFSH5 groups was examined. Differences in superovulation treatments were found for ATP levels. In the pFSH5 group, the ATP level was significantly lower than that of the other groups (5.63 +/- 0.14 for pFSH group versus 6.42 +/- 0.13 and 6.19 +/- 0.15 for rhFSH3 and pFSH3, respectively; P < 0.05). In a second phase, only 24.28% of pFSH5 ova developed into hatched blastocysts compared with 80.39% for the control group. A negative effect on oocyte quality was observed in the pFSH5 group in ATP production, it is possible that, after this superovulation treatment, oocyte metabolism would be affected
Acta Horticulturae
No full textDespite considerable differences in morphology, the genera representing 'true citrus fruit trees' are sexually compatible, but their phylogenetic relationships remain unclear. Most of the important commercial species of Citrus are believed to be of interspecific origin. By studying SNP and indel polymorphisms of 27 nuclear genes on 32 genotypes of Citrus and relatives of Citrus, the phylogenetic relationship between 'true citrus fruit trees' was clarified. Additionally, four mitochondrial (mtDNA) and five chloroplastic (cpDNA) SSRs markers were analysed for the citrus species to specify the maternal phylogeny of Citrus secondary species. A total of 16238 kb of DNA was sequenced for each genotype, and 1156 SNPs and 58 indels were identified. Nuclear phylogenetic analysis revealed that C. reticulata, Poncirus, and Fortunella form a clade that is clearly differentiated from the clade that includes three other basic taxa of cultivated citrus (C. maxima, C. medica and C. micrantha). Clymenia is included in a third strong clade with Eremocitrus and Microcitrus. The nuclear phylogeny of Citrus and its sexually compatible relatives was consistent with the geographic origins of these genera. The origin of Citrus secondary species was analysed both at nuclear and cytoplasmic level and the conclusions mostly agree with previous hypotheses. The SNPs and indels identified at the nuclear level from a relatively large discovery panel will be useful for systematic characterisation of citrus germplasm, both at intra-and inter-specific level
Maternal behaviour and welfare of the domestic and wild rabbit doe and its litter
Get PDFThe European rabbit (Oryctolagus cuniculus), in addition to its faunal interest in the western Mediterranean, is a relevant species which in several European countries is the basis of a meat-oriented, industrial livestock subsector, while in many developing countries rabbits are raised under alternative systems aimed at income integration and food security. In addition to meat production, other productive ori-entations exist that generate a variety of rabbit production systems. This paper reviews the ethology of maternal behaviour of the breeding doe and her litter, including its endocrine regulation, both in wild animal and in industrial and alternative farming systems, and its relation to management factors, productivity and performance as well as the welfare of the species. It also discusses the implications of the regulations concerning animal welfare on housing, management and satisfaction of behavioural needs of breeding does and their litters, which in some countries tend to provide more space and environmental enrichment in cages
Acta Horticulturae
No full textIn recent years we have generated various collections of citrus mutants. One objective of these collections is the selection of genotypes of commercial interest. In the present communication we describe 3 lines derived from clementine (Citrus clementina) through physical mutagenesis, named ‘Clemenverd’, ‘Nero’ and ‘Neufina’. These lines that show enhanced agronomic traits as related to the parental genotype have been registered. ‘Clemenverd’ shows delayed external maturation. ‘Nero’ is an early cultivar of seedless clementine that maintains the excellence of clementine quality. On the other hand, ‘Neufina’ holds well into February the commercial organoleptic qualities of the parental cultivar. ‘Neufina’ also has excellent perdurability in the tree, making it an ideal option to extend the supply of clementines during winter
Flooding Impairs Fe Uptake and Distribution in Citrus Due to the Strong Down-Regulation of Genes Involved in Strategy I Responses to Fe Deficiency in Roots
Get PDFThis work determines the ffects of long-term anoxia conditions-21 days-on Strategy I responses to iron (Fe) deficiency in Citrus and its impact on Fe uptake and distribution. The study was carried out in Citrus aurantium L. seedlings grown under flooding conditions (S) and in both the presence (+Fe) and absence of Fe (-Fe) in nutritive solution. The results revealed a strong down-regulation (more than 65%) of genes HA1 and FRO2 coding for enzymes proton-ATPase and Ferric-Chelate Reductase (FC-R), respectively, in -FeS plants when compared with -Fe ones. H+-extrusion and FC-R activity analyses confirmed the genetic results, indicating that flooding stress markedly repressed acidification and reduction responses to Fe deficiency (3.1- and 2.0-fold, respectively). Waterlogging reduced by half Fe concentration in +FeS roots, which led to 30% up-regulation of Fe transporter IRT1, although this effect was unable to improve Fe absorption. Consequently, flooding inhibited 57Fe uptake in +Fe and -Fe seedlings (29.8 and 66.2%, respectively) and 57Fe distribution to aerial part (30.6 and 72.3%, respectively). This evidences that the synergistic action of both enzymes H+-ATPase and FC-R is the preferential regulator of the Fe acquisition system under flooding conditions and, hence, their inactivation implies a limiting factor of citrus in their Fe-deficiency tolerance in waterlogged soils
Climatic distribution of citrus black spot caused by 'Phyllosticta citricarpa'. A historical analysis of disease spread in South Africa
Get PDFCitrus black spot (CBS), caused by Phyllosticta citricarpa, is one of the main fungal diseases of citrus worldwide. The Mediterranean Basin is free of the disease and thus phytosanitary measures are in place to avoid the entry of P. citricarpa in the EU territory. However, the suitability of the climates present in the Mediterranean Basin for CBS establishment and spread is debated. As a case study, an analysis of climate types and environmental variables in South Africa was conducted to identify potential associations with CBS distribution. The spread of the disease was traced and georeferenced datasets of CBS distribution and environmental variables were assembled. In 1950 CBS was still confined to areas of temperate climates with summer rainfall (Cw, Cf), but spread afterwards to neighbouring regions with markedly drier conditions. Actually, the hot arid steppe (BSh) is the predominant climate where CBS develops in South Africa nowadays. The disease was not detected in the Mediterranean-type climates Csa and Csb as defined by the Koppen-Geiger system and the more restrictive Aschmann's classification criteria. However, arid steppe (BS) climates, where CBS is prevalent in South Africa, are common in important citrus areas in the Mediterranean Basin. The most noticeable change in the environmental range occupied by CBS in South Africa was the amount and seasonality of rainfall. Due to the spread of the disease to dryer regions, the minimum annual precipitation in CBS-affected areas declined from 663 mm in 1950 to 339 mm at present. The minimum value precipitation of warmest quarter also declined from 290 to 96 mm. Strong spatial autocorrelation in CBS distribution data was detected, so further modelling efforts should consider the relative contribution of environmental variables and spatial effects to estimate the potential geographical range of CBS