Leonardo de B. Giordano

Reaction of tomato hybrids carrying the Ty-1 locus to Brazilian bipartite Begomovirus species

The number of tomato-infecting begomoviruses has increased in Brazil after the introduction of the polyphagous vector Bemisia tabaci biotype B. The Ty-1 locus, introgressed from Lycopersicon chilense, controls tolerance to species of the monopartite Tomato yellow leaf curl virus (TYLCV) complex in Europe and the Middle East. However, little information is available about the Ty-1 effectiveness against species of the bipartite Begomovirus complex occurring in Brazil. Heterozygous (Ty-1/ty-1) and homozygous (ty1/ty-1) hybrids were evaluated for reaction to Begomovirus isolates under open field conditions in two growing areas in Central Brazil. Test plants were evaluated under natural inoculation with high vector pressure. Evaluation was done using a disease assessment scale (DAS) varying from 1= no symptoms to 4= severe symptoms. Systemic infection was evaluated via polymerase chain reaction (PCR) using ‘universal’ Begomovirus primers. In the trial #1, the hybrids (Ty-1/ty-1) and (ty-1/ty-1) had 35% and 95% of plants with symptoms and 75% and 100% of plants with positive PCR, respectively. In the trial #2, only 20% of the Ty-1/ty-1 hybrid plants were symptom-free with both hybrids displaying 100% of plants with positive PCR. This reaction of the Ty-1 hybrid to bipartite Begomovirus species was similar to that reported in Europe and the Middle East to the TYLCV complex with a large number of plants being neither virus-free nor symptom-free. On the other hand, symptom expression of the Ty-1 hybrid was significantly milder than ty-1/ty-1 hybrids in both trials (DAS = 1.35 vs. 2.70 for the trial #1 and DAS = 2.05 vs. 3.95 for the trial #2). Nucleotide sequencing indicated the presence of isolates genetically related to Tomato rugose mosaic virus (ToRMV) in the trial #1 and a mixed infection of ToRMV and Tomato yellow vein streak virus in the trial #2. Therefore, the Ty-1 locus seems to control a “tolerance” response to distinct Begomovirus species. Resistance gene clusters is a common feature in the tomato genome, particularly at the chromosome 6 where Ty-1 is located. Therefore, additional studies are necessary to confirm if this tolerance to a range of begomoviruses is controlled by Ty-1 alone or a by the action of distinct, closely linked genes.

Inheritance of resistance to the bipartite Tomato chlorotic mottle begomovirus derived from Lycopersicon esculentum cv. ‘Tyking’

Severe outbreaks of bipartite begomoviruses (family Geminiviridae) have been observed on tomatoes after the introduction of the whitefly Bemisia tabaci (biotype B) in Brazil. The Lycopersiconesculentum line ‘TX 468-RG’ was identified as one of the best sources of broad-spectrum resistance to species comprising the tomato-infecting Begomovirus complex in Brazil. The genetic basis of resistance to one Begomovirus isolate was investigated using populations from the cross between ‘TX 468-RG’ (P1) and the susceptible line ‘Ohio 8245’ (P2). Parental lines, F1, backcross (BC) to P1 and BC to P2 and F2 generations were inoculated at the two true-leaf stage using 20 viruliferous whiteflies per plant. Assessment was done two weeks after inoculation based upon visual analysis of symptom expression. The ratio of resistant to susceptible plants closely fit to a single recessive gene (locus) model. The sequence analysis indicated that the Begomovirus isolate used in this assay was closely related to the bipartite Tomato chlorotic mottle virus. Therefore, this gene/locus, was tentatively named tcm-1 (tomato chlorotic mottle virus resistance-1). This locus has been transferred to distinct tomato cultivars and levels of resistance similar to that of ‘TX 468-RG’ were observed in advanced (F8 and F9) generations. In addition, breeding lines carrying the tcm-1 locus were also resistant to other Brazilian bipartite tomato-infecting Begomovirus species.

Efeito da infecção precoce por Begomovirus com genoma bipartido em características de frutos de tomate industrial

oBrix) utilizando uma cultivar de tomateiro para processamento industrial suscetivel a Begomovirus. A inoculacao controlada das mudas (18 dias apos semeadura) foi realizada inicialmente em casa de vegetacao usando moscas-brancas (Bemisia tabaci biotipo B) viruliferas, sendo as mudas expostas aos insetos por quatro dias. Um grupo de mudas nao inoculadas (controles) foi mantido isolado em uma casa de vegetacao livre do inseto vetor. Plantas inoculadas e nao inoculadas foram simultaneamente transplantadas em campo e dispostas em um delineamento de blocos ao acaso com quatro repeticoes com dez plantas por parcela. A analise de sequencia de nucleotideos de parte do genoma do DNA-A do virus utilizado na inoculacao indicou ser um isolado distinto, mas geneticamente relacionado com Tomato chlorotic mottle virus (uma das especies do complexo de Begomovirus infectando tomateiro no Brasil). Foi observada diferenca significativa para producao total, sendo 109,0 t/ha nas plantas controle e 48,2 t/ha nas mudas submetidas a inoculacao precoce; tendo-se reducao de aproximadamente 60% na produtividade. A diferenca mais acentuada foi observada para o parâmetro numero de frutos por planta. As plantas nao infectadas apresentaram uma media de 66 frutos, enquanto que nas plantas infectadas esta media foi de 38 frutos. O peso medio e o teor de solidos soluveis dos frutos nao foram significativamente influenciados pela infecao precoce. Desta forma, existe a possibilidade de reduzir perdas de produtividade devido a infecao de Begomovirus por meio do manejo adequado do sistema de producao, incluindo isolamento de viveiros e sementeiras e datas de transplantio. Com estes resultados salienta-se a importância epidemiologica de, quando possivel, retardar ao maximo o processo de infecao precoce por Begomovirus em mudas de tomateiro.

Contribuição portuguesa à produção e ao consumo de hortaliças no Brasil: uma revisão histórica

After the discovery of Brazil in 1500 and the beginning of its systematic colonization in 1530, the Portuguese have gradually settled along the Brazilian coast. An extensive exchange of plants, including vegetables, took place among Portugal, Brazil and other possessions in Africa and Asia by the Portuguese colonizers, sailors and Jesuits. In addition to diversifying the food, these introductions served as basic materials for breeding, often carried out empirically, searching the adaptation of these species to Brazilian soils and climate. After the eighteenth century, with the discovery of gold in Minas Gerais, Portuguese immigration to Brazil was intensified, with a strong urban development. Also, in the middle of the eighteenth century, there was a strong and systematized immigration from Acores to the South of Brazil. With it, many varieties of vegetables, specially onion and carrot, were brought to Brazil. Most of the Brazilian varieties originated from this material. Cultivar Baia-Periforme, the predominant onion variety in the Brazilian Southeast until the advent of hybrids, originated from selection within the portuguese cultivar Garrafal. The Creole onions, still today the most planted in Southern Brazil, were originated from germplasm brought by the Azoreans. In carrots, the so-called tropical germplasm, formed by selection of materials brought by the Azoreans, was the basis for the genetic improvement of tropical carrot, culminating with the release of cultivar Brasilia, in 1981, the most planted cultivar in summer. The Portuguese have left a profound legacy for Brazilian culture, present in some of our habits, including food habits. In the year we are completing 200 years of the arrival of the Portuguese royal family to Brazil, it is our opportunity to mention the Portuguese contributions to the production and consumption of vegetables in Brazil.

Print-capture PCR for detection of tomato begomoviruses from plants and whiteflies

Print-capture (PC) Polymerase chain reaction (PCR) was evaluated as a novel detection method of plant viruses. Tomato (Lycopersicon esculentum) plants infected with begomovirus (fam. Geminiviridae, gen. Begomovirus) and viruliferous whiteflies were used to study the efficiency of the method. Print-capturing steps were carried out using non-charged nylon membrane or filter paper as the solid support for DNA printings. Amplified DNA fragments of expected size were consistently obtained by PCR from infected plants grown in a greenhouse, after direct application of printed materials to the PCR mix. However, virus detection from a single whitefly and from field-grown tomato samples required a high temperature treatment of printed material prior to PCR amplification. Comparison of nylon membrane and filter paper as the solid support revealed the higher efficiency of the nylon membrane. The application of print-capture PCR reduces the chances of false-positive amplification by reducing manipulation steps during preparation of the target DNA. This method maintains all the advantages of PCR diagnosis, such as the high sensitivity and no requirement of radioactive reagents.

Effect of Ogura male-sterile cytoplasm on the performance of cabbage hybrid variety

SummaryCabbage hybrid seeds are commercially produced by means of self-incompatibility. This system may show some instability mainly under tropical conditions, where cytoplasmic male sterility can be an alternative approach for hybrid seeds production. However, cabbage hybrids holding Ogura male-sterile cytoplasm show some irregularities during development. By assessing some characteristics during the growing cycle of male-sterile cabbage hybrids and comparing them to genomic similar male-fertile ones and to the most common cabbage hybrid cultivated in Brazil, it was observed that the male-sterile hybrids had the same vigour, uniformity, number of leaves, resistance to Xanthomonas campestris pv. campestris, and earliness as their male-fertile counterparts and performed better than the commercial check hybrid for some of these characteristics. Although male-sterile hybrids showed yellowing of leaves, some parental combinations succeeded in overcoming or strongly reducing this cytoplasmic effect.

'BRS Tospodoro': a high lycopene processing tomato cultivar adapted to organic cropping systems and with multiple resistance to pathogens

ABSTRACT ‘BRS Tospodoro’ is a high lycopene tomato cultivar, which combines multiple disease resistance genes and desirable processing traits. This cultivar was found to be suitable for both conventional and organic crop systems. ‘BRS Tospodoro’ was obtained via backcross breeding using ‘Viradoro’ as recurrent parent and the inbred line ‘CNPH 1306’ as the donor of the Pto gene (resistance to Pseudomonas syringae pv. tomato race 0). ‘BRS Tospodoro’ has the Mi1-2 gene that controls resistance to root-knot nematodes ( Meloidogyne incognita , M. javanica, and M. arenaria ) as well as tolerance to populations of the aphid Macrosiphum euphorbiae (vector of Potyvirus species), and to whiteflies ( Bemisia tabaci ). ‘BRS Tospodoro’ has also the Sw-5b gene, which controls resistance to major Tospovirus species ( Groundnut ringspot virus , Tomato chlorotic spot virus , Chrysanthemum stem necrosis virus , and Tomato spotted wilt virus ). This cultivar is also resistant to Stemphylium solani and S. lycopersici

Cultivo de embriões de tomate in vitro visando a introgressão de genes de Lycopersicon peruvianum em L. esculentum

Three culture media in combination with distinct accessions, crossing generations and periods of time after artificial pollination were evaluated in order to identify more efficient protocols to recover interspecific hybrids between Lycopersicon esculentum and L. peruvianum. Both type of media for seed plating and the interval time for fruit harvest after artificial pollination had significant influence on the recovery of interspecific hybrids. The HLH medium gave the best results. The interval between 25 and 35 days after the artificial pollination was found to be the ideal for recovering interspecific hybrids. For acclimation, the L. esculentum and L. peruvianum plants were evaluated as well as plants of the interspecific hybrids (F1) and those from the RC1 and RC2 generations. This process was affected by the size of the buds used in the seedling transfer before acclimation as well as by the accesses and the time period over which the plantlet was in the test tube. The hybrids presented a better acclimation ability. The ideal period ranged between 26 and 35 days after transferring the seedling to the test tube. The acclimation accomplished under mild environmental conditions improved the plantlet survival.

Absorção de nutrientes e resposta à adubação em linhagens de tomateiro

Twenty nine processing tomato inbred lines were evaluated for their efficiency in nutrient uptake and in their response to fertilization. Two field assays were carried out at Embrapa Hortalicas, Brazil, with distinct fertilization dosages in 2006. In the first assay 1/3 of the total fertilization was applied when compared with the second assay. The experiments were conducted using a completely randomized design with three replications. The criteria to rank the inbred lines in both assays were the DRIS (Diagnosis and Recommendation Integrated System) index value and fruit yield. The critical values in order to distinguish efficient versus non-efficient as well as responsive versus non-responsive inbred lines were the average increase in both DRIS index value and fruit yield. Differences were detected among inbred lines for the uptake efficiency for all nutrients and for response to fertilization. The inbred lines 03, 40, 09 and 22 were classified as responsive to fertilization and efficient in N uptake; the lines 03, 04, 09, 13, 15 and 29 were for P; 03, 05, 10, 21, 22, 25 and 27 for K, 05, 10, 21, 22, 25, 27 and 29 for Ca; 04, 13, 15, 27 and 29 for S and B; 03, 05, 09, 10 and 27 for Cu. The inbred lines with the best performance were 27 in relation to nutrient absorption, and the lines 03, 04, 05 and 29 in relation to fertilization response.

A reliable begomovirus inoculation method for screening Lycopersicon esculentum lines

Due to failures of infection after mechanical inoculation of begomovirus on tomato (Lycopersicon esculentum Mill.) plants, an efficient and reliable begomovirus inoculation method was developed using the whitefly vector (Bemisia tabaci). Virus acquisition was carried out using a ‘Tube-cage’, made of a polypropylene tube, containing one to two day-old whiteflies and a tomato plant apex infected with a begomovirus isolate. After 48 h of acquisition access period, inoculation was done using a ‘Ring-cage’, containing viruliferous whiteflies, attached to the abaxial side of the leaf of young tomato plants. 48 hours after acquisition, the whiteflies were eliminated and the inoculated plants were incubated for 28 days under greenhouse conditions. Three viruliferous whiteflies per plant were enough to cause infection in susceptible tomato cv. Viradoro. This procedure was applied to test the resistance of tomato line 486-1 (resistant line) in comparison with ‘Viradoro’ (susceptible cultivar). Dot blot hybridization confirmed the susceptibility of ‘Viradoro’ and the resistance of the line 486-1, showing the efficiency of this method for screening plants for disease resistance. This method is also a useful tool in detecting the presence of virus in inoculated (lower leaves) and in non-inoculated (upper leaves) in a given plant. Using this procedure, it was observed that the resistance of the line 486-1 probably is expressed in the inoculated leaf without virus translocation to the upper leaves.