Introgressão assistida por marcadores de genes de resistência às cercosporioses em linhagens de amendoim

Leaf spots are among the main foliar disease of peanut crop, leading to an expensive management with fungicides sprays to avoid yield losses. However, some wild species are source of resistance genes, as for example Arachis cardenasii. Here we describe the evaluation of 45 peanut progenies and lines and the selection of six peanut lines related to the wild species Arachis batizocoi, A. magna and A. cardenasii. The cultivars BRS 421 OL and IAC OL3 were used as susceptible checks. We evaluated two experiments: one with 12 genotypes, under complete random block design with three replications; another with 35 genotypes with incomplete block design. No fungicides were sprayed in the experimental area; the severity in the checks was very high. The leaf spots resistance was evaluated with a severity scale (1 to 9) and the data evaluated under incomplete block design-group of experiments using the mixed model (REML/BLUP). The F4 line 2020-3108 was evaluated with complete resistance (rate 1), and other six lines were evaluated with severity values under rate 3. All these lines were selected in interspecific progenies evaluated in 2019-20 for leaf spots resistance, genotyped with molecular markers to detect genes associated with resistance derived from A. cardenasii.  Despite the resistance to leaf spots, all these lines need improvement for agronomic traits, and will be used as donor of leaf spots resistance in crossings with high yielding lines and cultivars, in order to select peanut cultivars with higher levels of resistance to leaf spots. Six pre-breeding strains with high levels of resistance to brown eye spot were identified, originating from the species A. cardenasii, A. magna, and A. batizocoi.