Zucchini lineages with levels of resistance to ZYMV and SqMV viruses

Zucchini (Cucurbita pepo L.) is a horticultural plant species of great socioeconomic value in tropical countries such as Colombia and Brazil. The production of zucchini is qualitatively and quantitatively affected by many diseases, especially viruses belonging to the Potyvirus (Zucchini yellow mosaic virus ZYMV) and Comovirus (Squash mosaic virus SqMV) groups. The primary strategy to reduce the spread of potentially damaging plant viruses is the development of genotypes with genetic tolerance; however, there are not many zucchini genotypes with multiple tolerance. Therefore, this study evaluated 66 zucchini genotypes to find sources of tolerance to the ZYMV and SqMV viruses. This experiment was conducted in a completely randomized design using genotypes from the germplasm bank of the Federal University of Uberlândia, including the genotypes: Emanuela (common commercial genotype) ‘Tronco Caserta’ (susceptible genotype) and PX 13067051 (resistant genotype). Leaf extracts containing viral particles were used as inoculant, and the distribution of grades of tolerance was recorded at the seedling stage. The lineages UFU-C×UFU-A#18#3;1, UFU-C×UFU-F#19#11;3, UFU-F#4#9;1, and UFU-D×UFU-F#7#21;1 and the Emanuela cultivar are alternatives for the production of new zucchini genotypes or hybrids with tolerance to the viruses ZYMV and SqMV. More severe symptoms were observed, as well as a larger number of susceptible genotypes for the ZYMV virus, indicating that this virus has great potential for causing damage and losses to zucchini crops. Additional keywords: Cucurbita pepo; marrow zucchini; courgetti; Zucchini yellow mosaic virus; Squash mosaic virus; genetic tolerance. 1 Federal University of Uberlândia (UFU), Agrarian Science Institute (ICIAG), Uberlandia (Brazil). ORCID Beloti, I.F. : 0000-0001-5914-0831; ORCID Maciel, G.M. : 0000-0002-3004-9134; ORCID Alves, I.M. : 0000-0002-2282-1964; ORCID Pereira, L.M. : 0000-0002-8716-4539; ORCID Lemes, E.M. : 0000-0001-6807-0644 2 Corresponding author. ernanefito@gmail.com Doi: https://doi.org/10.17584/rcch.2021v15i1. 10693 REVISTA COLOMBIANA DE CIENCIAS HORTÍCOLAS Vol. 15 No. 1, e10693, January-April 2021 e-ISSN: 2422-3719 · ISSN-L: 2011-2173 Among the pumpkin family, the zucchini (Cucurbita pepo L.), also commercially known as marrow zucchini, courgette, or Italian pumpkin, is widely used for raw consumption or in many cooking recipes. This horticultural fruit is an important source of B vitamins, niacin, calcium, phosphorus and iron. In Brazil, zucchini is among the top ten vegetables because of the great economic and social value, which can be found with a light green color, white or green with dark-colored stripes (Couto et al., 2009). Several phytosanitary problems cause considerable damage to this crop, such as powdery mildew (Podosphaera xanthii), anthracnose (Colletotrichum gloeosporioides f. sp. cucurbitae), black rot (Didymella bryoniae), fusarium wilt (Fusarium oxysporum), bacterial blackleg (Pectobacterium carotovorum subsp. carotovorum) and virus (Papaya ringspot virus, Zucchini yellow mosaic virus, Squash mosaic virus and Watermelon ringspot virus) (Nogueira et al., 2011; Agrofit, 2017). Among the diseases that occur in cucurbits, those caused by viruses seriously affect the quality and quantity of fruit production, representing one of the most important limiting factors for this crop production (Finetti-Sialer et al., 2012; Yesil, 2019). The phytoviroses have no curative control, and, thus, preventive measures are needed for crop management (Rodríguez et al., 2016; Cutler et al., 2018). Existing strategies to decrease dissemination include the development of cultivars or hybrids with genetic resistance to viral infections (Nogueira et al., 2011). More than 20 species of viruses can naturally infect cucurbits, and those that belong to the genus Potyvirus (family Potyviridae) have proven to be the most important, especially ZYMV (Zucchini yellow mosaic virus). The symptoms include chlorosis of leaf veins, usually in the first leaves. The presence of severe mosaic and systemic necrosis presents a yellowish color in the leaves and sharp reductions in plant development (Finetti-Sialer et al., 2012). The fruits are stunted and deformed, resulting in reduced yield and making them non-marketable (Spadotti et al., 2015). ZYMV is markedly present in the producing regions of Brazil; Barbosa et al. (2016), in a survey in the Vale do Rio São Francisco, obtained 44% symptomatic plants with the presence of this virus. Other viruses of importance include the Squash mosaic virus (SqMV), a member of the Comovirus genus of the subfamily Comovirinae, Family Secoviridae, and RESUMEN El calabacín (Cucurbita pepo L.) es una especie de planta hortícola de gran valor socioeconómico en países tropicales como Colombia y Brasil. Su producción se ve afectada tanto cualitativa como cuantitativamente por muchas enfermedades en especial por los virus pertenecientes a los grupos Potyvirus (Virus de mosaico amarillo de Zucchini ZYMV) y Comovirus (Virus de mosaico de calabaza SqMV). La estrategia principal para reducir la propagación de virus vegetales potencialmente dañinos es el desarrollo de genotipos con tolerancia genética; sin embargo, no hay muchos genotipos de calabacín con tolerancia múltiple. Por lo tanto, este estudio evaluó 66 genotipos de calabacín para encontrar fuentes de tolerancia a los virus ZYMV y SqMV. El experimento se llevó a cabo en un diseño completamente aleatorio utilizando genotipos del banco de germoplasma de la Universidad Federal de Uberlândia, incluyendo los genotipos: ‘Emanuela’ (genotipo comercial común), ‘Caserta’ (genotipo susceptible) y ‘PX 13067051’ (genotipo resistente). Los extractos de hojas que contienen partículas virales se utilizaron como inoculantes y la distribución de los grados de tolerancia se registró en la etapa de plántula. Los linajes UFU-C×UFU-A#18#3;1, UFU-C×UFU-F#19#11;3, UFU-F#4#9;1, UFU-D×UFU-F#7#21;1, y el cultivar Emanuela son alternativas para la producción de nuevos genotipos de calabacín o híbridos tolerancia a los virus ZYMV y SqMV. Se observaron síntomas más graves, así como un mayor número de genotipos susceptibles para el virus ZYMV, lo que indica que este virus tiene un gran potencial para causar daños y pérdidas al cultivo de calabacín. Palabras clave adicionales: Cucurbita pepo; calabacín de médula; courgette; Zucchini yellow mosaic virus; Squash mosaic virus; tolerancia genética. Received: 02-03-2020 Accepted: 31-10-2020 Published: 02-01-202