Family agriculture is a rich germplasm source wherever it takes place; however, information on genetic variability of this type of culture in Brazil is scarce. Samples of melon (Cucumis melo L.) accessions grown by family agriculture were rescued and this study aimed at characterizing the genetic variability in one sample of these accessions so as to identify the melon subspecies and the corresponding varieties. Fifteen accessions and their S 1 progenies were characterized (quantitative and qualitative descriptors) in two field experiments carried out in randomized blocks. Data on the parental and S 1 generations were compared and it was possible to identify the subspecies Cucumis melo subsp. agrestis and their varieties C. melo var. makuwa and C. melo var. momordica, and the subspecies C. melo subsp. melo and its variety C.melo var. cantalupensis, although some sub-accessions remained unidentified. A total of 26 subaccessions were found. UPGMA grouping method showed a high genetic diversity among and within accessions and sub-accessions. Clusters were formed by the melon subspecies, although there were discrepancies. Nonetheless, there is indication of trait introgression from the two melon subspecies and their varieties in the material grown by the family farmers of the state of Maranhão.
-Mixed infections in cucurbits are frequently observed in natural conditions between viruses from the Potyvirus genus and Cucumber mosaic virus (CMV), which significantly decreases productivity. The objectives of the present study was to compare the host range of PRSV-W, WMV, and ZYMV isolates and evaluate the effects of mixed infections with CMV in zucchini plants (Cucurbita pepo L.). Host range studies comprising 23 plant species confirmed some similarities and biological differences among the isolates of PRSV-W, ZYMV, and WMV. RT-PCR confirmed the amplification of DNA fragments of the PRSV-W, WMV, and ZYMV coat protein gene (cp) and cytoplasm inclusion gene (ci). The virus interaction studies in zucchini Caserta plants indicated synergistic interactions, particularly among species from the Potyvirus genus, and some CMV interference with some virus combinations. Keywords
The Northeastern Brazil has a great potential for production of melon (Cucumis melo) and watermelon (Citrullus lanatus). More than 20 virus species have been found naturally infecting cucurbit species around the world, but only seven of them were already found infecting those cucurbit crops in Northeastern Brazil. Plant viruses have been identified by several methods involving their morphological, physical, biological, cytological, serological and molecular properties, but serology is one of the most specific and accessible methods to obtain a rapid and precise diagnosis of a plant disease caused by virus. Several serological techniques were developed and the advent of the enzyme-linked immunosorbent assay (ELISA) has facilitated the use of serology in the identification and characterization of plant viruses, including those infecting melon and watermelon. Virus infections in melon and watermelon are considered of great importance because they can seriously affect yield all over the world, mainly in developing countries. The present review describes biological, morphological, serological and molecular properties of important virus species infecting melon and watermelon in commercial fields of Northeastern Brazil. The review covers the virus species from the following family and genera: Potyviridae
A enxertia tem sido empregada para conferir resistência às plantas, possibilitando o cultivo em áreas contaminadas por patógenos do solo e quando realizada sobre porta-enxertos apropriados, oferece uma série de vantagens agronômicas em relação ao cultivo convencional. O objetivo desse trabalho foi avaliar a taxa de sobrevivência e o desempenho agronômico e qualitativo da cultivar BRS Opara enxertada por encostia em quatro genótipos de abóbora (Cucurbita moschata): BGC 186, BGC 217, BGC 830 e BGC 830.1; e em dois genótipos de melancia forrageira (Citrullus lanatus var. citroides): BGCIA 223 e BGCIA 857. Quantificou-se a taxa de sobrevivência, em casa de vegetação, sob delineamento experimental inteiramente casualizado; a produtividade das plantas enxertadas e não-enxertadas, bem como os frutos foram caracterizados quanto às seguintes características: formato, coloração externa e interna, massa fresca, firmeza da polpa, sólidos solúveis do centro da polpa e da polpa homogeneizada, acidez titulável, relação sólidos solúveis/acidez titulável e pH. Para a avaliação agronômica e qualitativa dos frutos adotou-se o delineamento experimental de blocos ao acaso com quatro repetições e parcelas com cinco plantas. A taxa de sobrevivência das mudas enxertadas, após o "desmame", variou em função do porta-enxerto, sendo as melhores taxas observadas em BGC 186 e BGC 830.1. Comparando-se ao rendimento da testemunha (23,5 t/ha), houve um incremento médio de 66,5% na produtividade das plantas enxertadas em BGCIA 223, BGC 830, BGC 217 e BGCIA 857. Para a cultivar BRS Opara, pode-se recomendar inicialmente, estes porta-enxertos que determinaram incremento na produtividade sem afetar a qualidade dos frutos.
Caracterização biológica e sorológica de um isolado de Squash mosaic virus e efeitos da infecção mista com vírus do gênero Potyvirus (22) ABSTRACT -The conditions of soil and climate in the northeast of Brazil are favorable to cultivation of melon (Cucumis melo). However, there are various sanitary problems that affect productivity, especially diseases caused by viruses. This research had the objective of carrying out the biological and serological characterisation of an isolate of the Squash mosaic virus (SqMV), obtained in the State of Ceará, Brazil. In studies into host range, the virus infected systemically only five species of Cucurbitaceae family, and caused local lesions in Chenopodium amaranticolor and C. quinoa. Mixed-infection studies of SqMV with a virus specie from the genus Potyvirus demonstrated a synergistic effect between the viruses. Chemical purification of SqMV was possible using melon plants, and immunisation of rabbits with the purified preparation enabled the production of a specific polyclonal antiserum. The antiserum produced presented titers of 1:10,000 when evaluated by plate-trapped antigen enzyme-linked immunosorbent assay (PTA-ELISA), 1:160,000 by immunoprecipitation ELISA (IP-PTA-ELISA) and 1:1,024 by agar double diffusion. Studies by agar double diffusion of the serological relationship between SqMV and the Cowpea severe mosaic virus (CPSMV), of the genus Comovirus, demonstrated a unilateral relationship against their homologous and heterologous antisera.
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