Biology subjects

Lawrence-Paul, E. H.

Publications and source records attributed to Lawrence-Paul, E. H..

3 recordsLinked to original sources

bioRxiv2025

Strigolactone effects on Sorghum bicolor ecophysiology and symbioses

Strigolactones are ecologically, developmentally, and physiologically important hormones, but much remains unknown about their evolution and role in non-model species. Sorghum is a globally important C4 cereal and exhibits natural variation in root-exuded strigolactones. Differences in sorghum strigolactone stereochemistry are associated with resistance to parasitic plants, but with evidence for potential trade-offs. We studied sorghum mutants of loci in the strigolactone biosynthetic pathway, CAROTENOID CLEAVAGE DIOXYGENASE 8 (SbCCD8b) and LOW GERMINATION STIMULANT 1 (LGS1), previously shown to be Striga resistant by stimulating little germination of the parasite. SbCCD8b CRISPR-Cas9 deletions changed the accumulation of low abundance metabolites, reduced net carbon assimilation rate, altered root architecture and anatomy, and diminished the establishment and benefit of mycorrhizal symbionts. For Striga-resistant LGS1 CRISPR-Cas9 deletions, differentially expressed genes were enriched with promoter motifs for stress response and growth pathways, net carbon assimilation rate was reduced, and the colonization of mycorrhizal symbionts was delayed. We additionally restored functional LGS1 into the RTx430 genetic background, which normally has the lgs1-2 natural deletion allele. While root exudates from LGS1 insertion mutants rescued Striga susceptibility, we did not see consistent rescue of other traits impacted in LGS1 loss-of-function mutants. We hypothesize that epistasis with a neighboring strigolactone synthesis gene, which is rarely lost without concomitant loss of LGS1, may alter the phenotypic effects of LGS1 variation. Our study gives context to potential trade-offs associated with host resistance to parasitic plants and, more broadly, builds on the contribution of strigolactones in shaping sorghum physiological processes, growth, and development.

plant biology↗

bioRxiv2025

It's all in the timing: vegetative phase change alters selection under drought and contributes to local adaptation

The timing of developmental transitions is critical for adaptation, aligning stress-tolerant and sensitive stages with harsh and benign periods. At the same time, tradeoffs can promote diversity in development within populations. While geographic clines in developmental timing are often documented, there are few documented genetic tradeoffs in stress tolerance across developmental stages. Here, we study the juvenile-to-adult vegetative phase change (VPC), a conserved transition marked by changes in leaf morphology and physiology. In Arabidopsis, we found strong rank-changing genotype-by-environment interactions for fitness depending on the stage of drought exposure, indicating tradeoffs and stage-specific mechanisms of drought adaptation. Adult plants significantly increased water-use efficiency under drought, while juveniles did not, indicating lower juvenile plasticity. VPC timing varied with climate in Iberia, where genotypes from warm, dry climates transitioned earlier than those from cool, moist climates. However, SNPs associated with VPC timing and drought fitness showed little global geographic variation, suggesting tradeoffs maintain diversity across the species range. Genome-wide association mapping revealed candidate loci for VPC timing and stage-specific drought responses, several validated in T-DNA lines. Our results show that VPC timing contributes to drought adaptation and that genetic tradeoffs across developmental stages help maintain natural diversity.

plant biology↗

bioRxiv2024

Neighbor sensing through rhizodeposits in sorghum affects plant physiology and productivity

Plant-plant interactions play a crucial role in shaping the growth environment for crops, impacting their productivity and stress response. The interaction between plants aboveground has been studied and incorporated into breeding programs that select for plants that reduce aboveground competition between plants. However, few studies have focused on belowground interactions, and these looked at combined interactions and root partitioning in the soil. This study focuses on the developmental and physiological responses of sorghum (Sorghum bicolor L.) genotypes to neighboring sorghum plants. In this study, we used two growing methods: i) a focal plant surrounded by neighboring plants in the same pot but without shading, and ii) a focal plant grown either alone or surrounded by neighbors, irrigated with nutrient solution passed through pots (leachates) with or without plants. Our results showed that the presence of neighbors in the same pot led to reduced size-dry weight height, and leaf area of the focal plant. In addition, the presence of neighbors reduced stomatal conductance and PSII quantum yield. While the response direction was similar across tested genotypes, the magnitude varied. The results were repeated when neighboring plants were not grown in the same pot, but the nutrient solution passed through the root system of plants of the neighboring genotype. Furthermore, we saw a reduction in assimilation rate and stomatal conductance when plants were exposed to either the physical presence of neighbors or leachate. We did not find differences in root architecture in either treatment. These results show plants change their growth in response to neighbors and that the signal is carried through the liquid phase of the soil. Our findings provide insights into sorghum plants responses to below-ground signaling from neighboring plants and lay the foundation for future studies enabling increased crop performance under high-density planting conditions.

plant biology↗