Luciano Donizete Gonçalves

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.

Reação de híbridos, linhagens e progênies de pimentão à requeima causada por Phytophthora capsici e ao mosaico amarelo causado por Pepper yellow mosaic vírus (PepYMV)

Resistance to pepper blight induced by Phytophthora capsici and to yellow mosaic caused by a potyvirus species (PepYMV) are two priorities of most pepper (Capsicum annuum L.) breeding programmes in Brazil. The reactions of three commercial hybrids (Magali-R, Atenas F1, and Fortuna Super F1) to both P. capsici and PepYMV was studied, along with those of 20 experimental hybrids, 6 inbred lines and two F2:4 progenies from the Universidade Federal of Lavras pepper breeding programme. Trials in randomized complete block designs were carried out independently for each of the pathogens, with four and two replications, respectively. Each replications comprised 8 plants in 128-cell speeding styrofoam trays, kept in plastic-covered greenhouses protected with screen at the sides. Evaluation of symptoms was made from the 4th to the 14th and from the 15 th to the 40th day after inoculation (DAI) for P. capsici and PepYMV, respectively. Inoculation with P. capsici was made by dispensing 5mL of a 104 zoospore.mL-1 solution at the soil around the base of each plant. PepYMV was mechanically inoculated from extracts of previously infected leaves of TNN tobacco. Hybrids Magali-R and Fortuna Super were susceptible to P. capsici, while the hybrid Atenas, the access Criollo de Morellos 334, the progeny PIX-030 pl#03-2 and PIX-030 pl#06-3 (both originated from crosses with Criollo de Morellos), and the line PIM-013 were resistant. Among the experimental hybrids, three were also resistant to P. capsici, all three having PIM-013 as one of the parental lines. Resistance to PepYMV was found in Criollo de Morellos 334, progeny PIX-030 pl#03-2 and PIX-030 pl#06-3, and in the commercial hybrid Magali, besides 6 other experimental hybrids having line MYR-29 as one of the parental ines. The only treatment with resistance to both P. capsici and PepYMV were families PIX-030 pl#03-2 and PIX-030 pl#06-3, and the experimental hybrid F1(PIM-013 x MYR-29). Progeny PIX-030 pl#03-2 and PIX-030 pl#06-3 proved to be promissing sources of resistance to both pathogens to be deployed in breeding programmes. PIM-013 and MYR-29 are promissing sources of resistance to P. capsici and PepYMV, respectively, to be deployed in development of hybrids with resistance to these pathogens.Resistance to pepper blight induced by Phytophthora capsici and to yellow mosaic caused by a potyvirus species (PepYMV) are two priorities of most pepper (Capsicum annuum L.) breeding programmes in Brazil. The reactions of three commercial hybrids (Magali-R, Atenas F1, and Fortuna Super F1) to both P. capsici and PepYMV was studied, along with those of 20 experimental hybrids, 6 inbred lines and two F2:4 progenies from the Universidade Federal of Lavras pepper breeding programme. Trials in randomized complete block designs were carried out independently for each of the pathogens, with four and two replications, respectively. Each replications comprised 8 plants in 128-cell speeding styrofoam trays, kept in plastic-covered greenhouses protected with screen at the sides. Evaluation of symptoms was made from the 4th to the 14th and from the 15 th to the 40th day after inoculation (DAI) for P. capsici and PepYMV, respectively. Inoculation with P. capsici was made by dispensing 5mL of a 104 zoospore.mL-1 solution at the soil around the base of each plant. PepYMV was mechanically inoculated from extracts of previously infected leaves of TNN tobacco. Hybrids Magali-R and Fortuna Super were susceptible to P. capsici, while the hybrid Atenas, the access Criollo de Morellos 334, the progeny PIX-030 pl#03-2 and PIX-030 pl#06-3 (both originated from crosses with Criollo de Morellos), and the line PIM-013 were resistant. Among the experimental hybrids, three were also resistant to P. capsici, all three having PIM-013 as one of the parental lines. Resistance to PepYMV was found in Criollo de Morellos 334, progeny PIX-030 pl#03-2 and PIX-030 pl#06-3, and in the commercial hybrid Magali, besides 6 other experimental hybrids having line MYR-29 as one of the parental ines. The only treatment with resistance to both P. capsici and PepYMV were families PIX-030 pl#03-2 and PIX-030 pl#06-3, and the experimental hybrid F1(PIM-013 x MYR-29). Progeny PIX-030 pl#03-2 and PIX-030 pl#06-3 proved to be promissing sources of resistance to both pathogens to be deployed in breeding programmes. PIM-013 and MYR-29 are promissing sources of resistance to P. capsici and PepYMV, respectively, to be deployed in development of hybrids with resistance to these pathogens.

Caracterização e avaliação de acilaçúcar sintético no comportamento da mosca-branca Bemisia tabaci (Gennadius, 1886) biótipo B (Hemíptera: Aleyrodidae) em tomateiro

O cultivo de tomate e uma atividade de destaque no Brasil em termos de producao e consumo e os estados de Goias, Sao Paulo e Minas Gerais sao os principais produtores. Visando a desenvolver novos compostos com funcao inseticida, este trabalho foi desenvolvido com o objetivo de sintetizar acilacucares, aleloquimico presente nas folhas que conferem resistencia natural ao tomateiro Lycopersicon pennellii e avaliar seus efeitos no comportamento da mosca-branca. O delineamento utilizado foi o inteiramente casualizado, com cinco tratamentos e cinco repeticoes. Os ensaios consistiram dos seguintes tratamentos: plantas de tomate cv. Santa Clara pulverizadas com agua pura (testemunha); plantas de tomate cv. Santa Clara pulverizadas com acilacucar 01 (sintetizado a partir de sacarose); plantas de tomate cv. Santa Clara pulverizadas com acilacucar 02 (sintetizado a partir da glicose com cloreto de zinco como catalisador); plantas de tomate cv. Santa Clara pulverizadas com acilacucar 03 (sintetizado a partir da glicose com acetato de sodio como catalisador) e plantas de tomate Lycopersicon pennellii pulverizadas com agua pura. A concentracao do composto utilizada foi de 0,05%. Os resultados obtidos mostraram que o acilacucar 03 reduz a oviposicao do inseto no tomateiro. Todavia, se fazem necessarios estudos mais detalhados para se avaliar melhor a acao desse composto sobre a mosca-branca.

Doses e épocas de aplicação de molibdênio na produção e qualidade de alface americana

The influence of molibdenum dosages was evaluated on yield and quality of crisphead lettuce (Lactuca sativa L.). Three trials were carried out in Nazareno, Minas Gerais State, Brazil, from December/2001 to February/2002. The experimental design was a randomized complete block with four replications, being evaluated five molibdenum dosages (0; 90; 180; 240 and 360 g ha-1) and three application times of foliar-spraying (14; 21 and 28 days after transplanting). The total fresh matter presented quadratic effect where the dosage of 235 g ha-1 of molybdenum provided the highest yield. Significant differences between treatments were not observed for application times. The commercial fresh matter evidenced quadratic effect when molybdenum dosages were incremented, in function of the application dates. The doses of 236; 212 and 229 g ha-1 of molybdenum resulted in higher commercial production. The application of molibdenum 21 days after transplanting date showed the best results. Doses of 220 g ha-1 of molybdenum promoted bigger head circumference, when applied 14 and 21 days after transplanting date. There was no significant difference between treatments for stem length.

Teste de alelismo entre os mutantes de amadurecimento alcobaça e non-ripening em tomateiro

Since the early 1980s there are conflicting reports on the possible allelic relations between the tomato ripening mutants alc (=alcobaca) and nor (=non-ripening). In order to end these controversies, a test of allelism between the genes alc and nor was performed. A total of 364 plants of the F2 population between the tomato lines TOM-559 (alc/alc) and TOM-613 (nor/nor) were screened, along with 20 plants each of lines TOM-559 (alc/alc) and TOM-613 (nor/nor), of hybrids F1 [(TOM-559 x TOM-613), alc+/alc nor+/nor], F1 [(Floradade x TOM-559), alc+/alc nor+/nor+] and F1 [(Floradade x TOM-613), alc+/alc+nor+/nor], and of the normal phenotype line Floradade (alc+/alc+nor+/nor+). TOM-559 and TOM-613 are near-isogenic lines to Floradade, and differ from the latter only due to the presence of genes alc and nor, respectively. Floradade fruit harvested at the breaker stage show normal red color (normal phenotype) when fully ripe, whereas fruit of either TOM-559 or TOM-613 remain yellow or yellowish-orange (mutante phenotype). Four fruits per plant were harvested at the breaker stage and subsequently evaluated for their mature fruit color phenotype (normal or mutant). The results of the test of allelism indicate that the most likely hypothesis is that alc and nor are allelic to each other. Therefore, alc was considered to be a third allele at the nor locus, and the symbol norA was substituted for alc.