Research Highlights

Assessing and predicting field-scale soil N2O (nitrous oxide) emissions remains imprecise because much of N2O production occurs within very small soil volumes called “hotspots.” In this study, we found that water absorption by plant residue creates unique conditions that can result in accelerated N2O emissions.

Recent discoveries indicate that lignification is a flexible mechanism and that plants are capable of using a variety of phenolic compounds for the formation of lignin polymers. In this study, we report the occurrence of a new class of polyphenolic compounds – hydroxystilbenes – the second such class arising from outside the monolignol biosynthetic pathway, in the lignins of palm fruit endocarps.

Stem length is a key trait for various sorghum genotypes, impacting biomass yield, plant architecture, and other important crop features. In this study, we identified the gene encoded by Dw2, a locus known to affect stem internode length; this gene encodes a protein kinase homologous to a member of the AGC protein kinase family in the plant Arabidopsis.

Cellulosic bioenergy offers environmental benefits not available from other biofuels, but requires substantial amounts of land and creates the potential for environmental harm. It is therefore important to understand how different bioenergy crop and management choices will simultaneously affect climate mitigation, biodiversity, reactive nitrogen loss, and water use in future biofuel landscapes.

To improve bioenergy crop composition and yield, we seek to understand activation of the unfolded protein response (UPR) and its impact on the ability of plant cells to accumulate easily digestible carbohydrates such as mixed-linkage glucan (MLG). Here we identify a Brachypodium UPR transcription factor, UPR genes responsive to chemical or heat stress, and impacts of heat stress on MLG accumulation.

To develop bioenergy crops that produce extra lipids for extraction as oil biofuel, we examined whether lipid transport complexes of plants with different lipid acyl composition have diverged in their function.

Bioenergy sorghum accumulates 75% of shoot biomass in its stem internodes. To identify genes and molecular mechanisms that modulate the extent of internode growth, we conducted microscopic and transcriptomic analyses of four successive sub-apical vegetative internodes representing different stages of internode development of the bioenergy sorghum genotype R.07020.

We used transposon sequencing (Tn-seq) to identify essential genes in the bacterium Rhodobacter sphaeroides under several growth conditions. We then used that data to evaluate and refine an existing genome-scale metabolic model, providing more precise systems-level understanding of the diverse metabolic lifestyles of this bacterium.

To better understand flowering time control in temperate grasses, we sought to identify which genes prevent a grass from flowering until it has undergone prolonged cold exposure. After screening for and identifying mutants in the grass species Brachypodium distachyon, we identified a mutant that flowers rapidly without cold exposure and described and characterized a new gene we named REPRESSOR OF VERNALIZATION1 (RVR1).

Microbial production of lipids in high yield presents a significant challenge, often falling short of what can be theoretically obtained. This study characterized high-lipid mutant variants of Rhodobacter sphaeroides and showed that alterations to the bacterial cell envelope can result in increased accumulation of lipids relative to the parent strain.