Hybrids account for nearly all commercially planted varieties of maize and many other crop plants because crosses between inbred lines of these species produce first-generation [F1] offspring that greatly outperform their parents. The mechanisms underlying this phenomenon, called heterosis or hybrid vigor, are not well understood despite over a century of intensive research. The leading hypotheses—which focus on quantitative genetic mechanisms (dominance, overdominance, and epistasis) and molecular mechanisms (gene dosage and transcriptional regulation)—have been able to explain some but not all of the observed patterns of heterosis. Abiotic stressors are known to impact the expression of heterosis; however, the potential role of microbes in heterosis has largely been ignored. Here, we show that heterosis of root biomass and other traits in maize is strongly dependent on the belowground microbial environment. We found that, in some cases, inbred lines perform as well by these criteria as their F1 offspring under sterile conditions but that heterosis can be restored by inoculation with a simple community of seven bacterial strains. We observed the same pattern for seedlings inoculated with autoclaved versus live soil slurries in a growth chamber and for plants grown in steamed or fumigated versus untreated soil in the field. In a different field site, however, soil steaming increased rather than decreased heterosis, indicating that the direction of the effect depends on community composition, environment, or both. Together, our results demonstrate an ecological phenomenon whereby soil microbes differentially impact the early growth of inbred and hybrid maize.

Hybrids account for nearly all commercially planted varieties of maize and many other crop plants, because crosses between inbred lines of these species produce F1 offspring that greatly outperform their parents. The mechanisms underlying this phenomenon, called heterosis or hybrid vigor, are not well understood despite over a century of intensive research (Birchler et al. 2003). The leading hypotheses-which focus on quantitative genetic mechanisms (dominance, overdominance, and epistasis) and molecular mechanisms (gene dosage and transcriptional regulation)-have been able to explain some but not all of the observed patterns of heterosis (Stuber et al. 1992;Birchler 2015). However, possible ecological drivers of heterosis have largely been ignored. Here we show that heterosis of root biomass and germination in maize is strongly dependent on the belowground microbial environment. We found that, in some cases, inbred lines perform as well by these criteria as their F1 offspring under sterile conditions, but that heterosis can be restored by inoculation with a simple community of seven bacterial strains. We observed the same pattern for seedlings inoculated with autoclaved vs. live soil slurries in a growth chamber, and for plants grown in fumigated vs. untreated soil in the field. Together, our results demonstrate a novel, ecological mechanism for heterosis whereby soil microbes generally impair the germination and early growth of inbred but not hybrid maize.

A review of published literature was conducted to identify pasture pig production system features that pose risks to animal welfare, and to develop recommendations aimed at improving the wellbeing of the animals managed in those systems. Pasture pig production systems present specific challenges to animal welfare that are inherent to the nature of these systems where producers have little room to make improvements. However, these systems present other challenges that could be reduced with a carefully designed system, by adopting appropriate management strategies and by avoiding management practices that are likely to negatively affect animal wellbeing. In pasture pig production systems, exposure to extreme temperatures, potential contact with wildlife and pathogens (especially parasites), vulnerability to predators, risk of malnutrition, pre-weaning piglet mortality, complexity of processes for monitoring and treating sick animals, and for cleaning and disinfection of facilities and equipment are among the main threats to animal welfare.

Synthetic microbial communities (SynComs) are a valuable tool to study community assembly patterns, host-microbe interactions, and microbe-microbe interactions in a fully controllable setting. Constructing the SynCom inocula for plant-microbe experiments can be time consuming and difficult because a large number of isolates with different media requirements and growth rates are grown in parallel and mixed to appropriate titers. A potential workaround to assembling fresh SynCom inocula for every experiment could be to pre-make and freeze SynComs on a large scale, creating ready-to-use stock inocula. The objective of this study was to compare the reproducibility, stability, and colonization ability of freshly prepared versus frozen SynCom inocula. We used a community of seven species known to colonize maize roots. The results from inoculation with the frozen SynCom were as consistent as standardized de novo construction of fresh SynCom. Our results indicate that creating frozen SynCom inocula for repeated use in experiments not only saves time, but could also improve cross-experiment reproducibility. Although this approach was only validated with one SynCom, it demonstrates a principle that can be tested for improving approaches in constructing other SynComs.

Flowers emit volatile compounds that attract pollinators. In ornamental plant breeding programs, fragrance is a significant character that adds value to flowers for its consumer appeal. In Hawaii, anthurium (Araceae) is an important crop used for cut flowers and flowering potted plants. Unlike other ornamentals, fragrance is not presently associated with commercial anthuriums. However, several anthurium species are known to have distinctive scents. To obtain the novelty trait of fragrance in anthurium, an understanding of anthurium scent genetics, physiology, and chemistry is required. Scented anthurium species and hybrids in the Univ. of Hawaii germplasm collection have been studied. Fragrance emission among species varies with time of day—some species being scented only in the morning, only at night, or all day long. Fragrance emission also varies with stage of spadix development, with some species having scent as pistillate and/or staminate flowers. The species sampled comprise five categories: A. amnicola, A. formosum, and A. lindenianum are minty; A. armeniense is sweet; A. gracile is floral; A. bicollectivum, A. cerrobaulense, A. folsomii, and A. harleyii are fruity; and A. supianum is fishy. Some of the chemical components are illustrated.