Juliano Tadeu Vilela de Resende

Resistance of tomato genotypes with high level of acylsugars to Tetranychus evansi Baker & Pritchard

O acesso de Lycopersicon pennellii LA716 tem sido utilizado em programas de melhoramento do tomateiro devido a sua resistencia a artropodos-pragas, mediada pela presenca de acilacucares nos foliolos. Foi verificada a correlacao entre o teor de acilacucares em foliolos de tomateiros e a repelencia ao acaro Tetranychus evansi Baker & Pritchard. Foram selecionadas plantas contrastantes quanto aos niveis de acilacucares nos foliolos de populacoes F2 e F2RC1 (= F2 do primeiro retrocruzamento para Lycopersicon esculentum) do cruzamento interespecifico de L. esculentum TOM 584 (baixo teor de acilacucares) e L. pennellii LA 716 (alto teor). Foi realizado um teste de repelencia ao acaro T. evansi, tomando por base a distância percorrida pelos acaros nos foliolos. Os genotipos selecionados para alto teor de acilacucares, em media, foram responsaveis por reducoes significativas nas distâncias percorridas pelos acaros sobre a superficie do foliolo. A repelencia ao acaro T. evansi exercida pelas plantas selecionadas para alto teor de acilacucares deu-se de forma semelhante aquela conferida pelo genitor LA-716. As magnitudes das correlacoes encontradas confirmam a associacao entre altos teores do aleloquimico e a repelencia ao acaro.

Relação entre zingibereno, tricomas foliares e repelência de tomateiros a Tetranychus evansi

The objective of this work was to quantify zingiberene contents in a segregating population (F2) of the second backcross generation to Lycopersicon esculentum after the initial cross with the wild species L. hirsutum var. hirsutum, and to analyse the relationship between zingiberene and both glandular trichome density on tomato leaves and levels of repellence to spider mites Tetranychus evansi. A spectrophotometric assay was used to quantify zingiberene in leaf disks. Trichome counting was made in paradermic preparations of leaf and mite repellence was accessed by a quick thumbtack assay. Indirect selection for high zingiberene contents increased both glandular trichome density and the level of mite repellence. Zingiberene in glandular trichomes therefore mediates mite repellence in the tomato population. Glandular trichome densities, especially that of type VI trichomes, were highly and positively correlated with zingiberene contents. High zingiberene levels and their relationship with both glandular trichome densities and resistance (repellence) to spider mites remained significant after two backcross generations, indicating an indirect selection for high zingiberene as an effective way of selecting mite resistant tomato genotypes.

Yield and soluble solids contents of fruits of strawberry cultivars in protected cultivation

Protected cultivation is an alternative to control the climatic effects in different places and times of planting, however, its effects and interactions with the strawberry crop are little known. The goal of this study was to evaluate the effects of three cropping systems (high tunnel, low tunnel and field) on yield, mean fruit mass and the soluble solids contents of strawberry cultivars Dover, Camarosa, Sweet Charlie and Oso Grande in Guarapuava. Camarosa cultivar presents an excellent performance regarding yield and mean fruit mass in high and low tunnel cultivation; hence, these cropping system can be indicated. Fruits of Sweet Charlie cultivar had the highest content of soluble solids in all the cultivation environments. Yield and mean fruit mass obtained from high and low tunnels were significantly higher than in the field. The environment high tunnel allowed greater accumulation of soluble solids, differing significantly from other evaluated environments.

Acylsugar and the role of trichomes in tomato genotypes resistance to Tetranychus urticae

We evaluated the effect of tomato genotypes with a high content of acylsugar (AS) in the F2 generation on the behavior and biology of Tetranychus urticae, the two-spotted spider mite, the associated resistance mechanisms, and the role of trichomes in this resistance. Genotypes with a high AS content, and resistance to the spider mite (RVTA-2010pl#31 and RVTA-2010pl#94) were derived from interspecific crossing between wild accession LA-716 (Solanum pennellii, with high AS content), and cv. Redenção (S. lycopersicum, with low AS content). Free-choice and no-choice tests, and biological studies were conducted to determine the effect of genotype on the mite. The density and type of trichomes on both leaf surfaces and their correlations with AS and the assessed parameter were also determined. The results of the free-choice test demonstrated that the mites remaining on a plant and those laying eggs preferred the genotypes with low AS content to those with high AS content, thereby showing the non-preference resistance type. On the genotypes with high AS content, nymphs and adult females had a high mortality rate, adult females had a decreased oviposition rate, the duration of the egg incubation period increased, andviability of the egg and mite decresead. Thus, the mechanism of antibiosis was also associated in this resistance. A high density of type IV glandular trichomes was observed on the genotypes rich in AS. There was a significant positive relationship between AS content and density of type IV glandular trichomes. The density of glandular trichomes was positively correlated with mite mortality, and negatively correlated with attractiveness and oviposition.

Genetic similarity among strawberry cultivars assessed by RAPD and ISSR markers

Most strawberry (Fragaria × ananassa Duchesne) cultivars used in Brazil are developed in other countries, it became clear the need to start the strawberry breeding program in the country. To start a breeding program is necessary the genetic characterization of the germplasm available. Molecular markers are important tools that can be used for this purpose. The objectives of the present study were to assess the genetic similarity among 11 strawberry cultivars using RAPD and ISSR molecular markers and to indicate the possible promising crosses. The DNA of the eleven strawberry cultivars was extracted and amplified by PCR with RAPD and ISSR primers. The DNA fragments were separated in agarose gel for the RAPD markers and in polyacrylamide gel for the ISSR markers. The genetic similarity matrix was estimated by the Jaccard coefficient. Based on this matrix, the cultivars were grouped using the UPGMA method. The dendogram generated by the RAPD markers distributed the cultivars in three groups while the ISSR markers generated two groups. There was no direct relationship between the marker groups when the two types of markers were compared. The grouping proposed by the ISSR markers was more coherent with the origin and the genealogy of the cultivars than that proposed by the RAPD markers, and it can be considered the most efficient method for the study of genetic divergence in strawberry. The most promising crosses, based on the genetic divergence estimated from the RAPD and ISSR molecular data were between the Tudla and Ventana and the Oso Grande and Ventana cultivars, respectively.

Desempenho agronômico e qualidade físico-química de híbridos de tomateiro em cultivo rasteiro

The evaluation of cultivars within the same soil and climatic conditions allows comparison of genotypes for its yield and quality potential, seeking to establish the most adapted for each region. This study aimed to evaluate the yield and fruit quality of tomato hybrids grown without guiding, for fresh consumption and processing. The field experiment was carried out in Pinhao, Parana state, Brazil, in two years (2009/2010 and 2010/2011). The experimental design was a randomized complete block with four replications. Ten tomato hybrids were used (Supera, Granadero, AP-529, AP-533, Katia, Laura, Fascinio, Tinto, Red Spring and Venus). We evaluated total and marketable yield, average fruit weight, fruit damage, presence of peduncle; and characteristics of quality: dry mass, fruit firmness, mesocarp thickness, soluble solids, titratable acidity, soluble solids/titratable acidity ratio, pH, ascorbic acid, lycopene and reducing sugars. Granadero was the hybrid with the highest total yield (112.5 t ha-1 in 2009/2010 and 78.5 t ha-1 in 2010/2011) and marketable yield (88.7 t ha-1 in 2009/2010 and 69.0 t ha-1 in 2010/2011) in two years of experiment, as well as the highest dry matter and soluble solids and the highest mesocarp thickness. Tinto and Venus also stood out in total and marketable yield and the hybrid which had the highest average fruit weight was Venus (99.9 g). For the soluble solids/titratable acidity ratio, Granadero, Venus, Supera, Tinto and Fascinio showed ratios above 10 in both years. Laura, Red Spring and Venus showed good values for ascorbic acid and lycopene. Overall, the best performing hybrid for traits and for both segments was Granadero, but this hybrid showed low genotypic stability. So Venus and Tinto, despite lower yields, could be recommended because they presented good quality and stability to the region.

Genetic divergence among Brazilian garlic cultivars based on morphological characters and AFLP markers.

Outside its centers of origin, garlic propagates only asexually. Since asexual reproduction leads to the absence of meiotic recombination, the main garlic cultivars available for cultivation have arisen from the accumulation of somatic mutations in early cultivars. Thus, it is common for a single clone to have different names in different regions. This study aimed to evaluate the genetic diversity of 20 garlic cultivars by using morphological characters and amplified fragment length polymorphism (AFLP) markers to identify possible duplicate cultivars. We assessed 28 morphological characters related to the leaves, bulbs, and bulbils of the garlic plant and divided them into two categories: quantitative and qualitative (14 characters each). For molecular marker-based analysis, we used three AFLP primer combinations. Genetic divergence was calculated using the Jaccard coefficient; the cultivars were grouped using unweighted pair-group mean analysis. The average genetic divergence detected using the morphological characters was 2.30 (range, 0.45-4.70). Plant height and coat adhesion exhibited the highest divergence among the cultivars. The average genetic diversity based on AFLP data was 43% (range, 0-79%). Dendrograms derived from both techniques divided the cultivars into two groups: noble and semi-noble. Together with the divergence within groups, the correlation between morphological and molecular data suggested that the cultivars in the noble group had greater phenotypic stability than those in the semi-noble group. Analysis of Jonas and Quitéria cultivars using these two techniques revealed only slight differences, suggesting that these cultivars may be clones or have a high degree of kinship.

The role of glandular and non-glandular trichomes in the negative interactions between strawberry cultivars and spider mite

In tropical countries, spider mite (Tetranychus urticae Koch) is a major pest of strawberries. This pest is mainly controlled by the application of pesticides. Use of pest-resistant cultivars is a healthy and environment-friendly alternative to pesticide use. This paper describes the role of glandular and non-glandular trichomes in the interaction between strawberry cultivars and spider mite. The methodology used in this study was based on two bioassays. First, the thumbtack bioassay of Weston and Snyder was used to differentiate strawberry cultivars in terms of the distance travelled by the mites. Second, different types of trichomes present on the abaxial surface of the strawberry leaves were identified and counted. The results of this study showed a significantly negative correlation between the distance travelled by the spider mites and the density of glandular trichomes on the strawberry plant. The cultivars Camino Real and Dover had the highest densities of glandular trichomes and the shortest distance travelled by the mites. In contrast, the cultivars Ventana and Toyonoka had the lowest density of glandular trichomes and the longest distance travelled by the spider mites. The high density of glandular trichomes might have been responsible for the spider mite non-preference to the Camino Real and Dover strawberry cultivars, whereas the non-glandular trichomes minimally contributed to this non-preference. The results of this study affirm the role of glandular trichomes in negative interactions between strawberry and spider mites.

Produtividade e rendimento comercial de bulbos de cebola em função da densidade de cultivo

A distribuicao adequada das plantas de cebola (Allium cepa L.) na lavoura torna-se necessaria devido a influencia sobre a competicao por agua, luz e nutrientes, determinando o tamanho dos bulbos e a produtividade total. Objetivou-se, no trabalho, avaliar a produtividade e os padroes comerciais de bulbos de cebola, em funcao da densidade de plantio adotada. As mudas de cebola foram produzidas em bandejas de poliestireno de 200 celulas, com substrato comercial Plantimax®. O experimento foi instalado em delineamento experimental de blocos casualizados (DBC) com 4 repeticoes, com parcelas de 2 m2. Utilizou-se a cultivar Buccaneer, nas densidades de 50, 75 e 100 plantas m-2. Foram avaliadas a producao comercial, a producao total e a massa media de bulbos. Observou-se que a densidade de 100 plantas m-2 proporcionou a maior produtividade (92,20 t ha-1). No entanto, a menor densidade de plantas avaliada proporcionou bulbos com a maior massa media (171g). As densidades de 50 e 75 plantas m-2 apresentaram os maiores valores distribuidos na classe 4 (> que 70 ate 90 mm de diâmetro) e 3 cheio (> que 60 ate 70 mm de diâmetro), respectivamente. A densidade de 100 plantas m-2 proporcionou uma maior quantidade de bulbos na classificacao 3 cheio. Os resultados obtidos demonstraram que o aumento na densidade de plantas proporcionou uma maior produtividade, uma menor massa media de bulbos e uma maior producao na classificacao comercial 3 cheio, considerada ideal para comercializacao em funcao da preferencia pelos consumidores.

Desempenho agronômico e heterose de genótipos de cebola

The use of onion hybrids in Brazil is still recent, with little information regarding the gains from heterosis. However, the first step to exploit the heterosis is the evaluation of available germplasm. Due to the need for genotypes adapted to the climatic conditions of South-Central region of Parana state, Brazil, this study aimed to evaluate the agronomic performance of 19 hybrids and 50 inbred lines of onion, as well as the heterotic gain of six of these hybrids. The experimental design was randomized blocks with three replications. The evaluated traits were yield, average weight of the bulbs, commercial classification of bulbs, waxy of the leaves and cycle. In general the hybrids were superior to the lineages in yield and average bulb weight and had lower cycle. The heterotic gain in hybrids was evident, indicating the viability of hybrids for cultivation in the region. Hybrids 2572, 2573 and 2578 are promising due their high yield, earliness cycle and better classification of the bulbs. The lineages 2507-1 and 2983 provided the highest heterotic gain for the yield of the hybrid 2857, which was classified in the group of earliest genotypes, showing an inverse correlation between these two characters.