Biology subjects

Venado, R. E.

Publications and source records attributed to Venado, R. E..

4 recordsLinked to original sources

bioRxiv2025

Genetic determinants of aerial root traits that support biological nitrogen fixation in maize

Modern agriculture depends on chemically synthesized nitrogen fertilizer, which ensures high yields but also can carry significant environmental and economic costs. Biological nitrogen fixation (BNF) already supplies nitrogen to legume crops and several avenues of research are underway to extend it to non-legume crops. In maize (Zea mays), aerial roots have been shown to contribute to BNF in some varieties, and both having many aerial roots and large aerial roots contributes to the fixation trait. However, much of the genetics controlling aerial root number and size is still unknown. Here we validate and quantify BNF in maize varieties from Southern Mexico under controlled conditions and evaluate a population of double haploids derived from the elite inbred PHZ51 crossed with these varieties. We find that most aerial root traits (root number, nodes with roots, root size) are reasonably heritable (h2 0.5-0.75) and generally uncorrelated with each other. QTL mapping identifies 5 QTL each affecting nodes with aerial roots and aerial root number per node; in both cases all but 1 QTL show an increase from the landrace allele. We also identify 11 QTL for aerial root diameter, with most positive QTL coming from PHZ51. Between the two populations, only a few QTL overlap, indicating a presumably high diversity of genes affecting aerial root morphology in landrace populations. Combining the best QTL into elite material may provide a path toward meaningful levels of BNF for maize, and additional work is needed to determine how viable this approach will be in field settings.

plant biology↗

bioRxiv2024

Aerial root formation in Oaxacan maize (Zea mays) landraces persists into the adult phase and is minimally affected by soil nitrogen and ambient humidity.

Maize (Zea mays) is the most widely produced crop in the world, and conventional production requires significant amounts of synthetic nitrogen fertilizer, which has negative economic and environmental consequences. Maize landraces from Oaxaca, Mexico, can acquire nitrogen from nitrogen-fixing bacteria that live in a mucilage secreted by aerial nodal roots. The development of these nodal roots is a characteristic traditionally associated with the juvenile vegetative stage of maize plants. However, mature Oaxacan landraces develop many more nodes with aerial roots than commercial maize varieties. Our study shows that Oaxacan landraces develop aerial roots during both the juvenile and adult vegetative phases and even during early flowering under greenhouse and field conditions. Surprisingly, the development of these roots was only minimally affected by soil nitrogen and ambient humidity. These findings are an important first step in developing maize varieties that can reduce fertilizer needs in maize production across different environmental conditions.

plant biology↗

bioRxiv2023

Apoplastic barrier establishment in roots and nodules of Lotus japonicus is essential for root-shoot signaling and N-fixation

The molecular framework underlying apoplastic root barrier formation has been unveiled in the model species Arabidopsis thaliana where establishment of Casparian strips occurs at an early stage of root development. In legumes, this region overlaps with the area where nitrogen-fixing bacteria can induce nodule formation, termed the susceptible zone. Moreover, while nodules themselves also contain an endodermis spanning their vascular bundles, it is current unknown if Casparian strips serve as a filter for transport across this specialized organ. Here we establish barrier mutants in the symbiosis model Lotus japonicus. We find that the while genetic network controlling Casparian strip formation is conserved in this legume species, formation of functional barriers is crucial for establishment of N-fixing nodules. By probing this in detail, we establish a model where the Casparian strip, via its linked Schengen pathway, converge with long distance N signaling and systemic regulation of nodulation. Moreover, this also reveal that the genetic system for barrier establishment in the root endodermis is shared in nodule vascular endodermis and required for nodule function. Combined, our findings uncover a novel role of apoplastic root barriers and establishes a mutant collection suitable to probe the role of root barriers in symbiotic plant-microbe relationships.

plant biology↗

bioRxiv2023

Mucilage produced by sorghum (Sorghum bicolor) aerial roots supports a nitrogen-fixing community

Sorghum (Sorghum bicolor) is a significant crop globally, serving as an important source of food, feed, and fodder, and is increasingly recognized as an energy crop due to its high potential for biomass production. Certain sorghum accessions exhibit prolific aerial root development and produce abundant carbohydrate-rich mucilage after precipitation. This aerial root mucilage bears resemblance to that found in landraces of maize (Zea mays) from southern Mexico, which have previously been found to harbor diazotrophs. In this study, we examined the aerial root development of specific sorghum accessions and investigated the influence of humidity on this trait. Our microbiome analysis of the aerial root mucilage of maize and sorghum revealed the presence of numerous diazotrophs in sorghum mucilage, with Pseudomonadota, Bacillota, and Bacteriodota being the predominant phyla observed. However, the community composition varied significantly depending on the host plant and location. Through acetylene reduction, 15N2 gas feeding, and 15N isotope dilution assays, we determined that these sorghum accessions can acquire approximately 40% of their nitrogen from the atmosphere through these symbiotic associations on aerial roots. The nitrogen fixation occurring in sorghum aerial root mucilage presents a promising opportunity to reduce reliance on synthetic fertilizers and advance sustainable agricultural practices for food, feed, fodder, and bioenergy production.

plant biology↗