Biology subjects

Bernau, V.

Publications and source records attributed to Bernau, V..

3 recordsLinked to original sources

bioRxiv2026

Domestication, spread, and improvement have shaped biological nitrogen fixation traits in Zea taxa

Synthetic nitrogen fertilizers enhance maize (Zea mays ssp. mays) productivity but impose substantial environmental and economic costs. Some Mexican maize landraces support biological nitrogen fixation (BNF) in aerial root mucilage, raising the question of how much variation exists in this trait and how domestication, geographic spread, and improvement have shaped BNF-related traits across Zea in the Americas. We evaluated aerial root traits and BNF capacity across the maize domestication continuum using 60 Zea accessions grown in field experiments over two years under low-N conditions. Some accessions of wild Zea, landraces from Mexico and South America, and improved varieties had elevated nitrogen derived from the atmosphere (%Ndfa), ranging from 20 to 40%; some of these also had greater %Ndfa than typical improved varieties. Spread and improvement appear to have significantly reduced the number of aerial root-bearing nodes, with wild Zea and Mexican landraces consistently producing more. Nevertheless, the proportion of nitrogen derived from the atmosphere (%Ndfa) does not vary systematically across the domestication continuum. Thus, crop evolution shaped aerial root phenotypes more than associative BNF capacity. The persistence of substantial within-group variation indicates that the genetic potential for enhanced BNF remains within the Zea gene pool, providing opportunities to encourage and improve nitrogen use efficiency in maize cropping systems.

ecology↗

bioRxiv2022

Capturing the distribution as it shifts: chile pepper (Capsicum annuum L.) domestication gradient meets geography.

AimDomestication is an ongoing well-described process. However, while many have studied the changes domestication causes in the genetic landscape, few have explored the way domestication changes the geographic landscape in which the plants exist. Therefore, the goal of this study was to understand how the domestication status changed the suitable geographic space of chile pepper in its center of origin. MethodsCapsicum annuum is a major crop species globally whose domestication center, Mexico, has been well studied. This provides a unique opportunity to explore the degree to which ranges of different domestication classes diverged and how these ranges might be altered by climate change. To this end, we created ecological niche models for four domestication classes (wild, semiwild, landrace, modern cultivar) based on present climate and future climate scenarios for 2050, 2070, and 2090. ResultsConsidering present environment, we found substantial overlap in the geographic niches of all the domestication gradient categories. Yet, there were also clear unique environmental and geographic aspects to the current ranges. Wild and commercial varieties were at ease in desert conditions as opposed to landraces. With projections into the future, habitat was lost asymmetrically, with wild, semiwild and landraces at far greater risk than modern cultivars. Further, we identified areas where future suitability overlap between landraces and wilds is expected to decouple. Main conclusionsWhile range expansion is widely associated with domestication, there is little support of a constant niche expansion (either in environmental or geographical space) throughout the domestication gradient. However, a shift to higher altitudes with cooler climate was identified for landraces. The clear differences in environmental adaptation, such as higher mean diurnal range and precipitation seasonality along the domestication gradient classes and their future potential range shifts show the need to increase conservation efforts, particularly to preserve landraces and semiwild genotypes.

evolutionary biology↗

bioRxiv2020

Germination response of diverse wild and landrace chile peppers (Capsicum spp.) under drought stress simulated with polyethylene glycol

Responses to drought within a single species may vary based on plant development stage, drought severity, and the avoidance or tolerance mechanisms employed. Early drought stress can restrict emergence and seedling growth. Thus, in areas where water availability is limited, rapid germination leading to early plant establishment may be beneficial. Alternatively, germination without sufficient water to support the seedling may lead to early senescence, so reduced germination under low moisture conditions may be adaptive at the level of the population. We studied the germination response to osmotic stress of diverse chile pepper germplasm collected in southern Mexico from varied ecozones, cultivation systems, and of named landraces. Drought stress was simulated using polyethylene glycol solutions. Overall, survival time analysis revealed delayed germination at the 20% concentration of PEG across all ecozones. The effect was most pronounced in the genotypes from hotter, drier ecozones. Additionally, accessions from wetter and cooler ecozones had the fastest rate of germination. Moreover, accessions of the landraces Costeno Rojo and Tusta germinated more slowly and incompletely if sourced from a drier ecozone than a wetter one, indicating that slower, reduced germination under drought stress may be an adaptive avoidance mechanism. Significant differences were also observed between named landraces, with more domesticated types from intensive cultivation systems nearly always germinating faster than small-fruited backyard- or wild-types, perhaps due to the fact that the smaller-fruited accessions have generally undergone less selection. Thus, we conclude that there is evidence of local adaptation to both ecozone of origin and source cultivation system in germination characteristics of diverse chile peppers.

evolutionary biology↗