ABSTRACT 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.

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.

Resumo: O objetivo deste trabalho foi determinar os parâmetros genéticos e a eficiência de diferentes índices de seleção para linhagens de alface de folhas vermelhas (Lactuca sativa var. crispa) biofortificada e com potencial agronômico e nutricional. O experimento foi conduzido em delineamento de blocos ao acaso, com três repetições e 31 genótipos de alface do tipo crespa e com pigmentação roxa: a cultivar Belíssima, com baixa quantidade de carotenoides e rica em antocianina; e 30 linhagens provenientes do cruzamento entre as cultivares Belíssima e Uberlândia 10000, rica em carotenoides e com baixo teor de antocianina. As características avaliadas foram: massa verde total (g), diâmetro do caule (cm), número de folhas, diâmetro da planta (cm), temperatura foliar (°C), índice de desenvolvimento de análise de planta de solo (SPAD), teor de antocianina (mg por 100 g de amostra) e pendoamento (dias após a semeadura). Para as estimativas dos ganhos de seleção, foram selecionados 12 genótipos por meio de índices de seleção. O índice clássico proposto por Smith & Hazel e o índice da soma de “ranks” de Mulamba & Mock proporcionaram os maiores ganhos de seleção na alface biofortificada. O coeficiente de determinação genotípica para número de folhas, teor de antocianina, pendoamento e índice SPAD é de alta magnitude.

Abstract: The objective of this work was to determine the genetic parameters and the efficiency of different selection indices for biofortified red leaf lettuce (Lactuca sativa var. crispa) lines with agronomic and nutritional potential. The experiment was carried out in a randomized complete block design with three replicates and 31 crisp-textured and red-tinted leaf lettuce genotypes: the Belíssima cultivar, with a low carotenoid content and rich in anthocyanins; and 30 lines from the cross between the Belíssima and Uberlândia 10000 cultivars, rich in carotenoids and with a low anthocyanin content. The assessed traits were: total green mass (g), stem diameter (cm), leaf count, plant diameter (cm), foliar temperature (°C), soil plant analysis development (SPAD) index, anthocyanin content (mg 100 g-1 sample), and bolting (days after sowing). To estimate selection gains, 12 genotypes were selected through selection indices. The traditional index proposed by Smith & Hazel and the sum of ranks index by Mulamba & Mock provided the highest selection gains in the biofortified lettuce. The coefficient of genotypic determination for leaf count, anthocyanin content, bolting, and SPAD index is of high magnitude.

ABSTRACT Developing biofortified foods such as lettuce is a frequent goal of breeding programs. One obstacle to the success of these efforts is the high temporal and financial cost of determining leaf constituents. Image phenotyping has been increasingly used in crop breeding, but not in lettuce breeding. Until now, the use of image phenotyping to indirectly select carotenoid-rich lettuce inbred lines has not been reported. Therefore, the goal of this study was to use image phenotyping to select lettuce inbred lines with different carotenoid levels. Twenty-two inbred lettuce lines, resulting from the hybridization of the cultivars Pira 72 and Uberlândia 10000 and six successive selfings were evaluated. ‘Grand Rapids’, ‘UFU-Biofort’ and ‘Uberlândia 10000’ were used as controls. The following variables were evaluated: agronomic potential, apparent genetic diversity and image phenotyping. The data were submitted to the ANOVA F test (p ≤ 0.05) and means compared by the Scott–Knott test (p ≤ 0.05). Genetic divergence was represented by dendrograms constructed by UPGMA and the Tocher optimization method. The relative contribution of characters was assessed to identify the most relevant response variable. The genetic diversity of the evaluated germplasm bank was the greatest regarding soil plant analysis development (SPAD)/carotenoid values. Image phenotyping was successfully used to detect different levels of SPAD/carotenoid levels and could be a useful tool for plant breeding. The results of this study can be used to predict the nutritional values of the carotenoid content in lettuce leaves before commercialization.