Microbes and hybrid vigour in maize

The interaction between maize and soil microbes influences hybrid vigour, according to a recent study [1]. Many commercial varieties of crops such as maize are first-generation crosses of inbred lines, and their hybrid vigour leads to increased yield.

Research into the mechanisms underlying hybrid vigour has largely focused on genetics and physiology, but the potential role of microbes has not been well studied.

Maggie Wagner, Manuel Kleiner, and colleagues compared the growth of surface-sterilized kernels of two inbred maize lines and their hybrid, planted in individual growth bags containing sterilized soil treated with either a simplified synthetic community of seven bacterial strains or a sterile buffer.

The authors report that the inbred and hybrid lines were indistinguishable when grown in sterile soil, but the bacterial treatments resulted in lower root and shoot weights in the inbred lines, compared with the hybrid. The authors obtained similar results in a second growth-chamber experiment using a complex microbial slurry derived from farm soil and two field experiments with or without soil fumigation or steaming. However, mixed results from the soil-steaming experiments suggest that the composition of local microbial communities is important to hybrid vigour.

According to the authors, microbe-mediated hybrid vigour may be related to improved hybrid immune systems, overactive inbred immune systems, or both.