Performance of the molecular marker p779/p780 for classifying mode of reproduction and its association with agronomic traits in a guineagrass breeding program.

ABSTRACT - Apomixis in guineagrass (Megathyrsus maximus) breeding offers significant advantages, including the fixation of heterosis in the F1 generation, simplification of seed production, and enhancement of pasture uniformity in cultivars. Nevertheless, the segregation of mode of reproduction—apomictic versus sexual—within breeding populations necessitates the development of efficient and large-scale screening methods for the identification and selection of apomictic individuals. The objectives of this study were: (1) to evaluate the accuracy of the molecular marker p779/p780 in classifying the mode of reproduction of genotypes across diverse genetic backgrounds within a guineagrass breeding program; (2) to assess the correlation between the marker and key agronomic traits; and (3) to implement markerassisted selection (MAS) in a biparental population. To this end, the mode of reproduction of genotypes from the Embrapa guineagrass breeding program was determined using both conventional methodologies and the p779/p780 molecular marker. A logistic regression model was employed to assess the marker’s ability to classify the mode of reproduction. Additionally, correlation analyses between the marker and agronomic traits, as well as MAS application, were conducted in a biparental population. The p779/ p780 marker demonstrated high classification accuracy (>0.90) across multiple genetic backgrounds within the breeding program, indicating its robustness and reliability. However, despite its overall effectiveness, the marker was not found to be perfectly associated with the mode of reproduction in segregating populations. Inheritance of the marker followed a monogenic pattern (1 sexual:1 apomictic), and no significant correlations were observed between the marker and key agronomic traits. The implementation of MAS for mode of reproduction at early selection stages can enhance the efficiency of guineagrass breeding programs by enabling a high selection accuracy of apomictic genotypes without compromising selection gains for other agronomic traits.

Na publicação: Mariane Vilela, Mateus Santos