Nonrandom mating in Nicotiana attenuata and the paternal influence on seed metabolomes and pathogen resistance
In Nicotiana attenuata, after equal amounts of pollen from genetically different wild donors were simultaneously loaded onto the stigma, maternal plants (UtWT, Utah, USA) selected for self pollen in binary mixed pollinations. Furthermore, between two cross pollen donors (G2 and G10, Utah, USA), UtWT maternal plants selected less strongly against G2 than G10, when binary mixed pollinations of self and cross pollen were manually conducted. It is elusive that if the in vivo pollen tube (PT) growth rates of different pollen donors are involved in the nonrandom mating in N. attenuata. It is unknown if stylar secondary metabolites are involved in the nonrandom mating. Moreover, this study also tried to test if different paternal genotypes can impact on metabolomes and pathogen resistance of their offspring seeds. This study firstly provided a novel method to visualize the in vivo differential PT growth rates of two wild competitive pollen donors in the same style. It was demonstrated that the differential in vivo PT growth rates were involved in nonrandom mating. The in vivo PT growth rate was correlated with the seed siring in N. attenuata. It was revealed that 5 O-acyl sugars from styles may be involved in mate selection process in N. attenuata. In this study, the influence of paternal genotypes on their offspring seeds was investigated. In addition to the UtWT maternal genotype, 11 natural genotypes collected from Utah native populations were used as paternal lines. Similarly, on an AzWT (Arizona, USA) maternal genotype, 15 native genotypes collected from Arizona populations were used as paternal genotypes. Metabolomics analyses of seeds indicated that different paternal lines imparted their hybrid offspring seeds with distinct metabolomes. It suggested that Arizona paternal lines might confer their offspring seeds with different abilities of fungal pathogen resistances.