ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Response of maize seedling roots to changing ethylene concentrations
No full textMaize roots (Zea mays, cv. DK 626) growing in aerated solutions showed striking variations in the amount of ethylene produced during different stages of development. As endogenous ethylene increases, root elongation decreases. Exogenous 1-aminocyclopropane-1-carboxylic acid (ACC) supplied to these roots also inhibited their elongation and increased both the fresh weight of the apex and the ethylene produced. The inhibitor of ethylene biosynthesis, 2-aminoethoxyvinyl glycine (AVG), and the inhibitor of ethylene action, silver thiosulfate (STS), also reduced growth and increased swelling. As growth diminishes at reduced ethylene concentrations or with impeded ethylene action, these results support the view that ethylene is necessary for root growth. As ACC treatment also inhibited root elongation, it appears that ethylene was inhibitory at both low and high concentrations. Whereas ACC stimulated ethylene production 4 h after the beginning of treatment, inhibition of root elongation and promotion of fresh weight advanced slowly and needed 24 h to be established. At that time, root elongation reached a maximum response of 60% inhibition and 50% increase in weight. At 48 h, higher doses of ACC were required to provoke the same response as at 24 h. This suggests that the root growth progressively accomodates to higher ethylene concentrations
Complete nucleotide sequence of a Spanish isolate of Parietaria mottle virus infecting tomato
No full textThe genome of a Spanish isolate of Parietaria mottle virus (PMoV) obtained from tomato (strain PMoV-T) was completely sequenced. Protein motifs conserved for RNA viruses were identified: the p1 protein contained a metyltransferase domain in its N-terminal half and a triphosphatase/helicase domain in its C-terminal half, the p2 protein contained a RNA polymerase domain; the 3a protein contained a RNA-binding domain with alpha-helix and beta-sheet secondary structures. In addition, stem-loop structures with potential capacity of protein interactions were predicted on the untranslated terminal regions. Comparison with the other sequenced PMoV isolate showed nucleotide identities of 93, 90, and 93% for genomic RNAs 1, 2 and 3, respectively, and amino acid identities ranging from 88 to 97% for the different proteins. A cytosine deletion was detected at position 1,366 of RNA 3, involving a start codon for the coat protein (CP) gene different from the other PMoV isolate, resulting in a CP 16 amino acids shorter. Comparison of synonymous and nonsynonymous mutations revealed different selective constraints along the genome
Development of microsatellite markers from loquat, Eriobotrya japonica (Thunb.) Lindl.
No full textLoquat (Eriobotrya japonica) is a minor fruit which has become an interesting alternative into the European fruit industry. This interest resulted in a loquat germplasm collection established at the Instituto Valenciano de Investigaciones Agrarias, Valencia, Spain. Currently, it is the main reservoir of this species outside Asia. We developed and characterized the first 21 polymorphic microsatellite loci from a CT/AG-enriched loquat genomic library. The observed heterozygosity ranged between 0.20 and 1.00, expected heterozygosity ranged between 0.17 and 0.81, three markers were multilocus and eight loci departed significantly from Hardy-Weinberg equilibrium. These markers will facilitate diversity and genetic studies into the species
Evaluation of the efficacy of Steinernema carpocapsae in a chitosan formulation against the red palm weevil, Rhynchophorus ferrugineus, in Phoenix canariensis
Get PDFThe red palm weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera, Curculionidae), is an important pest of palms. It has recently colonized the Mediterranean Basin, where it is a serious problem on ornamental Phoenix canariensis (Chabaud) palms. The efficacy of Steinernema carpocapsae (Weiser) (Nematoda: Steinernematidae) in a chitosan formulation (Biorend R(A (R))) against this weevil in a semi-field trial including both preventative and curative assays has been studied. Our results prove the potential of this nematode to control R. ferrugineus. Efficacies around 80% were obtained in the curative assay, and up to 98% in the preventative treatment. Applications repeated every 2-3 weeks during the critical flight periods could prove effective to protect palms from this weevil in the Mediterranean Basin
Acta Horticulturae
No full textFruit breeding programs are recent in Spain. The first programs by conventional breeding started 33 years ago, in 1974. Breeding programs assisted by biotechnology started later, in 1996. The high increase produced during the 90's is astonishing. In the 70's only four programs were initiated and another four started in the 80's. Suddenly, twenty-four new breeding programs were initiated in the 90's and another twenty started since 2000. Fifty-two fruit breeding programs are currently active. This paper summarises causes that explain this challenge. Concerning species, the larger number of programs corresponds to stone fruits ( 32) in which peach species have 13 programs and apricot 7. Related to geographical distribution, Valencia is the most active in breeding with 11 programs, followed by Catalu a with 10 programs. Third in the ranking is Murcia with 8 programs. Funding comes from public, private and mixed sources. Nineteen programs are funded by public sources, 14 are funded by private sources and 19 are funded by mixed sources. The fruit breeding programs focused on variety breeding have as main and common objectives: sensory fruit quality, resistance or tolerance to pests and diseases, and better harvest calendar by means of early and late varieties that allow to extend the season while getting better market results. Additionally, there are other objectives specific per crop. In this paper, a description of the most important fruit breeding programs along with the main difficulties encountered by breeders on financial, scientific and technical aspects are included
Acta Horticulturae
No full textTwo breeding programs focused on stone fruit species are being carried out at the IVIA: an apricot breeding program started in 1993 and a peach breeding program started in 1997. The objective on apricot species is to obtain new, high-quality varieties resistant to the sharka virus with good adaptability to the Southern European environment. The sharka virus or PPV is the most limiting factor for apricot production. This virus, since its first detection in Spain in 1984, has caused enormous fruit losses and more than 1.5 million trees have been removed. The breeding program is focused on introgression of sharka resistance in locally grown cultivars. Currently, two cultivars that fulfil the objectives of the program are registered, and 13 advanced selections are under study in several apricot production regions in Spain. The peach-breeding program is aimed at obtaining new early and extra-early maturing peach and nectarine varieties, which surpass in fruit quality those currently available in the market. One of the main problems for peach culture and marketing is overproduction, due to increase in yield per hectare and expansion of the culture to subtropical areas. The main markets for Spanish production are European countries, which are great producers worldwide as well. In Valencia, Murcia, and part of Andalucia, climatic conditions allow the production of early cultivars whose ripening season does not overlap with those from the rest of European countries. In this paper, characteristics from 15 advanced selections from sharka resistant apricot and 12 peach selections that meet the objectives of the programs are described
Acta Horticulturae
No full textSomaclonal variation is considered to be a useful source of variation in several fruit species. A study was developed for in vitro propagation and plant regeneration using callus from the primordial and young leaves of the persimmon cultivar ‘Rojo Brillante’, to study in subsequent experiments somaclonal variation for qualitative and quantitative characters. The replacement of FeNaEDTA by FeEDDHA as iron source resulted in shoots of higher quality. Leaf explants taken from in vitro shoots were cultured on a modified Murashige and Skoog medium (MS½N) supplemented with various combinations of cytokinin (Z or BA) with different auxins (IAA or NAA). Optimal shoot regeneration was obtained with 9 mg L-1 (42 μM) zeatin and 0.1 mg L-1 (0.5 μM) NAA. Under these conditions, more than 20% of organogenic callus induction was obtained
Evaluation of brief potassium sorbate dips to control postharvest penicillium decay on major citrus species and cultivars
No full textSeveral commercially important citrus species and cultivars were artificially inoculated with Penicillium digitatum or Penicillium italicum, immersed 24 h later for 5, 15, 30, or 60 s in water (control) or aqueous solutions of 3% (w/v) potassium sorbate (PS) at 20, 53, 58, 62, 65, or 68 °C, rinsed with tap water, and incubated at 20 °C for 7 d. The most effective treatments were PS applications at 62 °C for 30 or 60 s, which reduced both penicillium molds by up to 20, 25, 50, 80, or 95% on ‘Clemenules’ and ‘Nadorcott’ mandarins, ‘Fino’ lemons, ‘Ortanique’ mandarins, and ‘Valencia’ oranges, respectively. After 60-d storage at 5 °C, green mold and blue mold on ‘Valencia’ oranges treated with PS at 62 °C for 60 s were reduced by 96 and 83%, respectively. Treatments applied to nonwounded fruit before inoculation did not induce disease resistance. In semicommercial trials with ‘Valencia’ oranges, treatments with heated PS alone, PS combined with the fungicide imazalil (IZ), and IZ alone were all equally effective. On ‘Marisol’ clementine mandarins, the combination PS + IZ at room temperature allowed a significant reduction of the IZ doses needed for effective control of green mol
Grapevine cv. 'Riesling' water use in the northeastern United States
No full textVine water use was measured in a Vitis vinifera cv. Riesling vineyard located in New York. Vines were fully irrigated and were trained via vertical shoot positioning giving a narrow curtain intercepting about 30% of the incident light during the sunlight hours. Vine water use was estimated on six vines by sap flow gauges directly calibrated with whole canopy transpiration measurements. The regression analysis between estimates of transpiration showed that there were large differences between vines in the calibration values obtained. Sap flow monitoring started late in June, about 2 weeks after bloom, when the canopy already filled the trellis system, and continued until October. Results showed that vine water use during most of the summer days was between 1.0 and 2.0 mm day(-1), with peak values around 2.5 mm. The basal (e.g. vine transpiration/reference evapotranspiration) crop coefficient (K (cb)) varied somewhat between days, but it was quite stable during the whole season. Averaged over the entire experimental period, the K (cb) was 0.49. Some of the day-to-day variation in the K (cb) was negatively related with daily average air vapour pressure deficit. This suggests that reference evapotranspiration models on grass may not be fully accurate for vines under these experimental conditions
Liberibacters Associated with Citrus Huanglongbing in Brazil: 'Candidatus Liberibacter asiaticus' Is Heat Tolerant, 'Ca. L. americanus' Is Heat Sensitive
No full textIn São Paulo State, Brazil, ‘Candidatus Liberibacter americanus’ and ‘Candidatus Liberibacter asiaticus’ are associated with huanglongbing (HLB). Affected municipalities occur mainly in the central and southern regions, where the annual number of hours above 30°C is two to five times lower than that in the extreme northern and western regions. The influence of temperature on sweet orange trees infected with ‘Ca. L. asiaticus’ or ‘Ca. L. americanus’ was studied in temperature-controlled growth chambers. Symptom progression on new shoots of naturally infected and experimentally graft-inoculated symptomatic sweet orange trees was assessed. Mottled leaves developed on all infected trees at 22 to 24°C, but not on any ‘Ca. L. americanus’–infected trees at 27 to 32°C. Quantitative, real time-PCR was used to determine the liberibacter titers in the trees. After 90 days, ‘Ca. L. asiaticus’–infected trees had high titers at 32 and 35°C, but not at 38°C, while ‘Ca. L. americanus’–infected trees had high titers at 24°C, but at 32°C the titers were very low or the liberibacters could not be detected. Thus, the multiplication of ‘Ca. L. asiaticus’ is not yet affected at 35°C, while a temperature of 32°C is detrimental to ‘Ca. L. americanus’. Thus, ‘Ca. L. americanus’ is less heat tolerant than ‘Ca. L. asiaticus’. The uneven distribution of these two liberibacters in São Paulo State might be in relation with these results