Letteratura scientifica selezionata sul tema "15B51"

The genetic control of resistance to Cucurbit aphid-borne yellows virus (CABYV; genus Polerovirus, family Luteoviridae) in the TGR-1551 melon accession was studied through agroinoculation of a genetic family obtained from the cross between this accession and the susceptible Spanish cultivar ‘Bola de Oro’. Segregation analyses were consistent with the hypothesis that one dominant gene and at least two more modifier genes confer resistance; one of these additional genes is likely present in the susceptible parent ‘Bola de Oro’. Local and systemic accumulation of the virus was analyzed in a time course experiment, showing that TGR-1551 resistance was expressed systemically as a significant reduction of virus accumulation compared with susceptible controls, but not locally in agroinoculated cotyledons. In aphid transmission experiments, CABYV inoculation by aphids was significantly reduced in TGR-1551 plants, although the virus was acquired at a similar rate from TGR-1551 as from susceptible plants. Results of feeding behavior studies using the DC electrical penetration graph technique suggested that viruliferous aphids can salivate and feed from the phloem of TGR-1551 plants and that the observed reduction in virus transmission efficiency is not related to reduced salivation by Aphis gossypii in phloem sieve elements. Since the virus is able to accumulate to normal levels in agroinoculated tissues, our results suggest that resistance of TGR-1551 plants to CABYV is related to impairment of virus movement or translocation after it reaches the phloem sieve elements.

ABSTRACTAtypical enteropathogenicEscherichia coli(aEPEC) strains are diarrheal pathogens that lack bundle-forming pilus production but possess the virulence-associated locus of enterocyte effacement. aEPEC strain 1551-2 produces localized adherence (LA) on HeLa cells; however, its isogenic intimin (eae) mutant produces a diffuse-adherence (DA) pattern. In this study, we aimed to identify the DA-associated adhesin of the 1551-2eaemutant. Electron microscopy of 1551-2 identified rigid rod-like pili composed of an 18-kDa protein, which was identified as the major pilin subunit of type 1 pilus (T1P) by mass spectrometry analysis. Deletion offimAin 1551-2 affected biofilm formation but had no effect on adherence properties. Analysis of secreted proteins in supernatants of this strain identified a 150-kDa protein corresponding to SslE, a type 2 secreted protein that was recently reported to be involved in biofilm formation of rabbit and human EPEC strains. However, neither adherence nor biofilm formation was affected in a 1551-2sslEmutant. We then investigated the role of the EspA filament associated with the type 3 secretion system (T3SS) in DA by generating a doubleeae espAmutant. This strain was no longer adherent, strongly suggesting that the T3SS translocon is the DA adhesin. In agreement with these results, specific anti-EspA antibodies blocked adherence of the 1551-2eaemutant. Our data support a role for intimin in LA, for the T3SS translocon in DA, and for T1P in biofilm formation, all of which may act in concert to facilitate host intestinal colonization by aEPEC strains.

Forty-four accessions of Cucumis melo L. and related wild species were tested for reaction to a yellowing disease, incited by the recently identified cucurbit yellowing stunting disorder virus (CYSDV), under natural and controlled-inoculation conditions. The C. melo TGR-1551 accession and one Cucumis metuliferus Naud. accession were asymptomatic. The segregation ratios obtained following controlled inoculations of the family produced by crossing TGR-1551 with the susceptible Spanish cv. Piel de Sapo revealed that the resistance to CYSDV in TGR-1551 is conditioned by a dominant allele at one locus. The name Cucurbit yellow stunting and symbol Cys is proposed for this locus.

RESUMO - Avaliar as características agronômicas e produtivas de híbridos de milho foi o objetivo deste trabalho. O delineamento experimental utilizado foi de blocos ao acaso, com quatro tratamentos e cinco repetições, sendo os tratamentos compostos por quatro híbridos de milho Agroeste: AS 1551 Convencional, AS 1551 PRO 2, AS 1656 PRO 3 e AS 1596 PROX. Foram avaliadas as características morfométricas da planta, a participação dos componentes estruturais no material ensilado e o potencial produtivo dos híbridos. O híbrido AS 1596 PROX apresentou maior número de folhas totais e senescentes, além de apresentar maior altura da planta e da inserção da espiga. As maiores participações de colmo (37,42%) e folha (16,25%) no material ensilado foram obtidas no híbrido AS 1656 PRO 3. Os híbridos AS 1551 Convencional e AS 1551 PRO 2 apresentaram maiores participações de espiga (52,42% e 50,01%) e de grãos no material ensilado (32,74% e 32,88%). As produtividades foram semelhantes, com valores de 37.662,3 a 45.093,0 kg/ha de matéria verde e de 14.404,7 a 16.421,6 kg/ha de matéria seca. O desempenho produtivo dos híbridos foi satisfatório, e a escolha deles vai depender do objetivo de cada propriedade, na busca de maiores benefícios e facilidades de manejo.Palavras-chave: Zea mays, componentes estruturais, grãos, matéria seca, diâmetro de colmo.PRODUCTIVE PERFORMANCE OF MAIZE HYBRIDS FOR THE PRODUCTION OF SILAGE USING THE WHOLE PLANTABSTRACT - The objective of this work was to evaluate the agronomic and productive characteristics of maize hybrids. The experimental design was a randomized block design with four treatments and five replicates. The treatments were composed of four Agroeste maize hybrids: AS 1551 Conventional, AS 1551 PRO 2, AS 1656 PRO 3 and AS 1596 PROX. The morphometric characteristics of the plant, the participation of the structural components in the ensiled material and the productive potential of the hybrids were evaluated. The AS 1596 PROX hybrid presented a higher number of total and senescent leaves, besides showing higher plant height and spike insertion. The highest stakes (37.42%) and leaf (16.25%) in the ensiled material were obtained in the hybrid AS 1656 PRO 3. The hybrids AS 1551 Conventional and AS 1551 PRO 2 showed greater spike (52.42 % and 50.01%) and grains (32.74% and 32.88%) participation in the ensiled material. The yields were similar with values from 37,662.3 to 45,093.0 kg/ha of green matter and from 14,404.7 to 16,421.6 kg/ha of dry matter. The productive performance of the hybrids was satisfactory, and their choice will depend on the objective of each property, in the search for greater benefits and management facilities.Keywords: Zea mays, structural components, grains, dry matter, stem diameter.