Evaluation of peanut genotypes for resistance to Tomato spotted wilt virus by mechanical and thrips inoculation

The objective of this work was to evaluate the reactions of three peanut breeding lines (IC-10, IC-34, and ICGV 86388) to Tomato spotted wilt virus (TSWV) by mechanical and thrips inoculation, under greenhouse conditions, and compare them to the reactions of cultivars SunOleic, Georgia Green, and the breeding line C11-2-39. TSWV infection by mechanical inoculation was visually assessed using an index ranging from 0 (no symptoms) to 4 (apical death). Enzyme-linked immunosorbent assay was used to confirm TSWV infection from both mechanical and thrips inoculations. IC-10, IC-34, ICGV 86388, and C11-2-39 were more resistant than the cultivars SunOleic and Georgia Green based on mechanical inoculation. Upon thrips inoculation only IC-34 and ICGV-86388 were infected by TSWV, as demonstrated by reverse transcription polymerase chain reaction (RT-PCR), although no symptoms of infection were observed. The peanut breeding lines IC-10, IC-34, and ICGV 86388 show higher level of resistance to TSWV than cultivar Georgia Green considered a standard for TSWV resistance.

Stability of Citrus tristeza virus protective isolates in field conditions

The objective of this work was to monitor the maintenance of Citrus tristeza virus (CTV) protective isolates stability in selected clones of 'Pêra' sweet orange (Citrus sinensis), preimmunized or naturally infected by the virus, after successive clonal propagations. The work was carried out in field conditions in the north of Paraná State, Brazil. Coat protein gene (CPG) analysis of 33 isolates collected from 16 clones of 'Pêra' sweet orange was performed using single strand conformational polymorphism (SSCP). Initially, the isolates were characterized by symptoms of stem pitting observed in clones. Then viral genome was extracted and used as template for the amplification of CPG by reverse transcription polimerase chain reaction (RTPCR). RTPCR products electrophoretic profiles were analyzed using the Jaccard coefficient and the UPGMA method. The majority of the clones had weak to moderate stem pitting symptoms and its CTV isolates showed alterations in the SSCP profiles. However, the stability of the protective complex has been maintained, except for isolates from two analised clones. Low genetic variability was observed within the isolates during the studied years.

Procedures for evaluating the tolerance of cassava genotypes to postharvest physiological deterioration

Abstract: The objective of this work was to define procedures to assess the tolerance of cassava genotypes to postharvest physiological deterioration (PPD) and to microbial deterioration (MD). Roots of six cassava genotypes were evaluated in two experiments, during storage under different environmental conditions: high temperature and low soil moisture; or low temperature and high soil moisture. Roots were treated or not with fungicide (carbendazim) before storage. Genotype reactions to MD and PPD were evaluated at 0, 2, 5, 10, 15, 20, and 30 days after harvest (DAH), in the proximal, medial, and distal parts of the roots. A diagrammatic scale was proposed to evaluate nonperipheral symptoms of PPD. Fungicide treatment and root position did not influence PPD expression; however, all factors had significant effect on MD severity. Genotypes differed as to their tolerance to PPD and MD. Both deterioration types were more pronounced during periods of higher humidity and lower temperatures. The fungicide treatment increased root shelf life by reducing MD severity up to 10 DAH. Whole roots showed low MD severity and high PPD expression up to 10 DAH, which enabled the assessment of PPD without significant interference of MD symptoms during this period.

First report of Pestalotiopsis diospyri causing canker on persimmon trees

During 2006 to 2009 season symptoms of a canker disease were observed on twigs and branches of young and mature persimmon trees (Diospyros kaki L.) cv. Fuyu in the States of Santa Catarina and Paraná in the Southern Brazil. The cankers result in severe damage and reduced production. Isolations from the margins of these cankers revealed a genus of Pestalotiopsis. Koch's postulates were confirmed using two isolates of the pathogen which was identified as Pestalotiopsis diospyri.

PREVENTION OF CHILLING INJURY IN 'TOMMY ATKINS' MANGOES PREVIOUSLY STORED AT 5 ºC, USING HEAT TREATMENT AND RADIATION UV (UV-C)

ABSTRACT The objective of this study was to evaluate the effect of heat treatment and ultraviolet radiation (UV-C) in the prevention of chilling injury in mangoes cv. Tommy Atkins previously stored or not under injury condition after their transference to ambient condition. Fruits were divided into groups: two were hydrothermally treated (46.1 ºC/90 min; 55 ºC/5 min) and two were exposed to UV-C radiation (1.14 kJ m-2; 2.28 kJ m-2). These groups were stored under chilling injury conditions (5 ºC for 14 days), as established in preliminary tests. Other untreated groups were stored at 12 ºC or 5 ºC. After the storage period, they were transferred to ambient conditions (21.9 ºC; 55% RH) and the quality was evaluated. All the data were submitted to multivariate analysis as the tool to verify the simultaneous effect of the treatments under the quality parameters. The multivariate analysis indicated that the hydrothermal treatments at 46.1 °C/90 min and 55 °C/5 min and the UV-C radiation at doses of 1.14 kJ m-2 and 2.28 kJ m-2 were effective in minimized the symptoms of chilling injury in mangoes ‘Tommy Atkins’ stored at 5 °C for 14 days. However, after their transference to environmental condition at 21.9 °C, only the UV-C kept this control, especially at a dose of 2.28 kJ m-2. This treatment did not prevent the development of the characteristic color or affected the normal ripening and allowed the conservation of fruit for a period of 14 days at 5 °C, plus seven days of storage at environmental condition, which corresponds to the shipping transportation plus the time for sale.

Analysis of passion fruit rinds (Passiflora edulis): isoorientin quantification by HPTLC and evaluation of antioxidant (radical scavenging) capacity

The content of isoorientin in passion fruit rinds (Passiflora edulis fo. flavicarpa O. Degener) was determined by HPTLC (high performance thin layer chromatography) with densitometric analysis. The results revealed a higher amount of isoorientin in healthy rinds of P. edulis (92.275 ± 0.610 mg L-1) than in rinds with typical symptoms of PWV (Passion fruit Woodiness Virus) infection (28.931 ± 0.346 mg L-1). The HPTLC data, allied to assays of radical scavenging activity, suggest the potential of P. edulis rinds as a natural source of flavonoids or as a possible functional food.

Woody Gall symptoms in different citrus species and varieties artificially colonized by the citrus brown aphid Toxoptera citricidus

Seedlings of 41 different citrus species and varieties were massively colonized with the citrus brown aphid Toxoptera citricidus, obtained from Pêra sweet orange (Citrus sinensis) trees, presenting symptoms of the "Capão Bonito" complex of the Citrus tristeza virus (CTV). The objective was to evaluate resistance or tolerance of the varieties to that virus complex, but even after eight months of inoculation no stem pitting was observed in the plants. Otherwise, the presence of galls similar to those induced by the vein enation-woody gall disease was observed in 73% of the plants of Volkamer Palermo (Citrus volkameriana), 60% of the Volkamer Catania 2, 2% of the Rangpur Lime D.22.30 (Citrus limonia), 13% of the Volkamer Australian Red, the Rangpur Lime hybrid, the Orlando tangelo (Citrus reticulata x Citrus paradisi) and the Florida Rough lemon (C. jambhiri), and 7% of the Carrizo citrange (Poncirus trifoliata x Citrus sinensis). The highest incidence and the largest gall size were observed in the Palermo Volkamer showing that this clone would be the most suitable to be used as an indicator plant in biological indexing tests for the disease. There are no previous reports in the literature about the occurrence of woody galls in Orlando tangelo and Carrizo citrange.

Mosaic in Senna occidentalis in southern Brazil induced by a new strain of Soybean mosaic virus

Plants of Senna occidentalis (sin. Cassia occidentalis) with mosaic symptoms were collected near a soybean (Glycine max) field where some plants exhibited symptoms of mosaic and blistering. A preliminary examination of leaf tissue from diseased S. occidentalis by electron microscopy revealed the presence of pinwheel inclusions as well as long flexuous particles, indicating the presence of a potyvirus. Host range, serology, and amino acid sequence from this potyvirus were similar to those from other Brazilian isolates of Soybean mosaic virus (SMV). The 3'- terminal region of the genomic RNA was cloned and a cDNA sequence of 1.9 kb upstream of the poly (A) tract was determined. The sequence contains a single open reading frame and a 3'- non-translated region (NTR) of 259 bp. The nucleotide sequence of the CP gene of SMV-Soc was 98% identical to that of Brazilian isolates SMV-B, SMV-L, and SMV-FT10. The percentage of nucleotide identity of their 3'-NTR's was 91, 98, and 99% in relation to SMV-L, SMV-B, and SMV-FT10, respectively. In contrast to other Brazilian SMV isolates studied, SMV-Soc was able to infect sunflower (Helianthus annuus). Based on these results, the S. occidentalis isolate was identified as a new strain of SMV belonging to the SMV strain, group G5 and was named SMV-Soc. This is the first report of naturaly occurring SMV infecting plants of S. occidentalis in Brazil, adding this weed as a new source of SMV in the field.

Genetic diversity of begomovirus infecting tomato and associated weeds in Southeastern Brazil

The genetic diversity of begomovirus isolates from tomato (Lycopersicon esculentum) fields in the Southeastern region of Brazil was analyzed by direct sequencing of PCR fragments amplified by using universal oligonucleotides for the begomovirus DNA-A, and subsequent computer-aided phylogenetic analysis. Samples of tomato plants and associated weeds showing typical symptoms of virus infection were collected at seven locations in the states of Minas Gerais, Espírito Santo and Rio de Janeiro. A total of 137 out of 369 samples were infected with a begomovirus based on PCR analysis. Phylogenetic analysis indicated a high degree of genetic diversity among begomoviruses infecting tomatoes in the sampled area. One species (Tomato chlorotic mottle virus, TCMV) occurs predominantly in Minas Gerais, whereas in Rio de Janeiro and Espírito Santo a distinct species, not yet fully characterized, predominates. Phylogenetic analysis further indicates the presence of an additional four possible new species. This high degree of genetic diversity suggests a recent transfer of indigenous begomovirus from wild hosts into tomatoes. The close phylogenetic relationship verified between begomovirus infecting tomato and associated weeds favors this hypothesis.

The role of petals in development of grey mould in strawberries

Studies were conducted in annual crops of strawberry (Fragaria x ananassa) (cv. Elsanta to assess the relative importance of petals as an inoculum source of grey mould, caused by Botrytis cinerea and to identify during which period of flower and fruit development the presence of petals has a significant effect on development of grey mould on fruits. In 1998, the incidence of B. cinerea on flower parts was assessed, and the symptoms of grey mould on fruits were characterised with regards to their starting point. The incidence of B. cinerea on petals was 65-85% of those flowers that harboured B. cinerea. The starting point of symptoms was located underneath the sepals in 65-85% of fruits with grey mould, and petals were present at this site in about 50% of the cases. In 1999, four field experiments were conducted to assess the effect of petal removal at different stages of flower and fruit development on incidence of grey mould. The incidence of grey mould on fruits with petals retained till harvest was circa 55% more than on fruits where petals were removed or had dropped naturally by the end of flowering, regardless of planting date or inoculum level of B. cinerea. The incidence of grey mould was hardly different between treatments where petals were removed at young flower stage, old flower stage, or green fruit stage. It is concluded that petals are an effective and stable source of inoculum for fruit infection by B. cinerea. Considering the high probability that retention of petals during fruit expansion and ripening results in fruit infection, the elimination of petals as an inoculum source appears worthwhile even when the incidence of petal retention on fruits is relatively low.

Soybean pod blight and root rot caused by lineages of the Fusarium graminearum and the production of mycotoxins

Surveys of soybean (Glycine max) seed grown in South Brazil revealed infection with Fusarium graminearum. To determine if members of this complex were pathogenic to soybean, six strains derived from soybean were added to soil at a rate of 10³ macroconidia/ ml or individual pods were inoculated with 10(4) macroconidia/ml. Seedlings grown in infested soil developed small necrotic lesions in the crown and upper roots. Pods inoculated with conidia developed large (>1 cm), dark brown, necrotic lesions. Younger pods inoculated with the fungus blighted and dropped from the plant. Strains of the F. graminearum complex recovered from lesions on the crown, roots and pods of soybean plants were identified as lineage 1, 2 or 8 by obtaining the DNA sequence from the EF1-alpha gene and comparing it to strains of the known lineage. Two strains of F. graminearum lineage 7 from the U.S. caused similar symptoms of the disease on soybean. Mycotoxin tests on soybean and wheat (Triticum aestivum) indicate that most Brazilian strains produce nivalenol as the major trichothecene mycotoxin rather than deoxynivalenol. In addition, strains from lineages 2 and 8 produce the novel trichothecene, 3-acetylnivalenol.

Biological and molecular characterization of an isolate of Tobacco streak virus obtained from soybeans in Brazil

A virus was isolated from soybean (Glycine max) plants with symptoms of dwarfing and bud blight in Wenceslau Braz County, Paraná, Brazil. The host range and properties resembled those of Tobacco streak virus (TSV). The purified virus showed three peaks in a frozen sucrose gradient. Antiserum was produced and the virus was serologically related to TSV. Electron microscopy detected 28 nm spherical particles. Coat protein (CP) had a Mr of 29.880 Da. A fragment of 1028 nt was amplified, cloned and sequenced. One open reading frame with 717 nt was identified and associated to the CP. The CP gene shared 83% identity with the sequence of TSV CP from white clover (Trifolium repens) (GenBank CAA25133). This is the first report of the biological and molecular characterization of TSV isolated from soybeans. It is proposed that this isolate be considered a strain of TSV named TSV-BR.

Annona squamosa, a new host of Ceratocystis fimbriata

Mango branch blight disease, caused by Ceratocystis fimbriata, is endemic to the municipality of São Fidelis in northern Rio de Janeiro State. In addition to mango, C. fimbriata was found associated with sugar apple trees (Annona squamosa) showing symptoms of branch blight in São Fidelis. Sugar apple and mango isolates from the same region had the same morphology and showed similar ITS-rDNA sequences. These sequences were also similar to other Brazilian isolates of C. fimbriata sensu stricto. Cross inoculation of such isolates obtained from diseased sugar apple and mango resulted in diseased symptoms on both plant species. This is the first record of A. squamosa as a host for C. fimbriata.

Performance of dairy heifers raised on Xaraés palissadgrass (Brachiaria brizantha cv. Xaraés) pasture supplemented with two types of mineral mixture

The effects of selective (e.g. mineral supplement formulated on the basis of nutritional and clinical examination of the herd) or commercial mineral supplementation of crossbred dairy heifers (Holstein-Mantiqueira), on daily weight gain (DWG), body condition score (BCS), age at first mating (AFM) and the intake of mineral mixture (IMM) managed on Xaraés palissadgrass pasture (Brachiaria brizantha cv. Xaraés) were evaluated from February 2006 to March 2008. Structural characteristics, forage allowance and nutritional value of Xaraés palissadgrass were also evaluated. The structural variables of pasture, allowances and nutritive value of forage, besides the DWG were only affected (p<0.05) by season, with highest results for spring and summer. Throughout the experimental period (730 days), no sign of mineral deficiency was detected in heifers that ingested the selective supplement. The DWG and AFM were not influenced by the mineral mixture offered (0.52 and 0.33 kg/day during the spring/summer and in fall/winter for DWG, respectively, and 813 days of AFM). The IMM was higher for commercial mineral mixture than for selective (61.6 and 51.0g/day respectively). The BCS was slightly higher for selective (3.17) than for the commercial (3.02) mineral mixture. Thus, the selective mineral supplement was a strategy to prevent mineral deficiency in this herd and resulted in similar performance at lower costs (e.g. due to less IMM) of crossbred heifers when compared with the commercial mineral supplementation.

Long term dietary deficiency in steers: vital functions and T3 and IGF-1 relationships

To evaluate the influence of diets with different degrees of energy deficiency on the hormonal profile and vital functions, 12 steers were randomly distributed into 3 groups of 4 animals. For 140 days, each group received (G1) a diet to promote a weight gain of 900gr/day (17.7 Mcal/d DE and 13% CP), (G2) 80% of the maintenance requirements (5.8 Mcal/d DE and 7% CP), or (G3) 60% of the maintenance requirements (4.7 Mcal/d DE and 5% CP). In G2 and G3, the energy deficit caused a marked decrease in the heart rate and respiratory rate and a reduction in the blood levels of Insulin like growth factor-1 (IGF-1) and triiodothyronine (T3). The decrease in heart rate, respiratory movement and, to a lesser extent, reduction of the rectal temperature, reflected the low status of energy and was negatively impacted by the low levels of T3. There was a strong correlation between the hormones T3 and IGF-1 (r=0.833). There were also strong correlations between T3 and HR (r=0.701), T3 and RR (r=0.632), IGF-1 and HR (r=0.731), and IGF-1 and RR (r=0.679). There were intermediate correlations between T3 and TºC (r=0.484), T3 and insulin (r=0.506), IGF-1 and insulin (r=0.517), and IGF-1 and TºC (r=0.548). This study showed the influence of a long period of providing an energy-deficient diet on animal performance, correlating hormonal status and vital functions in growing cattle. The results indicated that the evaluated parameters represent an important tool for the early detection of dietary deficiency.