Barcelos, C. | Search bioRxiv

bioRxiv2025

Physiological and Metabolic Responses of Chickpea to Post-Flowering High Temperatures and Limited Water Availability

Post-flowering elevated temperatures are increasingly frequent and strongly affect crop yield and seed nutritional quality. This study examined the impact of elevated post-flowering temperatures (32{degrees}C/25{degrees}C, day/night) combined with two watering regimes (40% and 10% field capacity) on chickpea genotypes. Elvar and Electra, top-yielding Portuguese genotypes well adapted to southern Portugals dry climate were evaluated. Under controlled high-temperature conditions (Phenolab), reproductive cycle was shortened to 30-35 days, compared with 65 days under greenhouse conditions (24{degrees}C/18{degrees}C). Water use peaked soon after flowering and declined after 19 days, regardless of genotype or watering regime, suggesting a physiological limitation on water use. Elevated temperature strongly reduced seed number and weight while altering composition. Nutrient density improved, with higher protein and mineral levels (P, Mg, S, Mo, Fe, Zn) and lower starch content, highlighting a consistent protein-starch trade-off unaffected by water availability. While growth environment largely determined composition, enzymatic activity patterns revealed genotype-specific differences in carbon metabolism (e.g. sucrose synthase, cell wall invertase, aldolase and phosphoglucose isomerase). Overall, these findings suggest genotype-specific responses driven by carbon metabolism and emphasize integrating metabolic, physiological and composition traits in breeding for yield stability and nutritional value. HighlightPost-flowering temperature dictates reproductive duration and seed composition, enhancing nutritional density but lowering yield. Protein-starch trade-off was consistent across genotypes, while enzymatic activity profiles enabled genotype discrimination under contrasting environments.

plant biology↗

bioRxiv2019

Chemoinformatic-guided engineering of polyketide synthases

Polyketide synthase (PKS) engineering is an attractive method to generate new molecules such as commodity, fine and specialty chemicals. A significant challenge in PKS design is engineering a partially reductive module to produce a saturated {beta}-carbon through a reductive loop exchange. In this work, we sought to establish that chemoinformatics, a field traditionally used in drug discovery, could provide a viable strategy to reductive loop exchanges. We first introduced a set of donor reductive loops of diverse genetic origin and chemical substrate structures into the first extension module of the lipomycin PKS (LipPKS1). Product titers of these engineered unimodular PKSs correlated with atom pair chemical similarity between the substrate of the donor reductive loops and recipient LipPKS1, reaching a titer of 165 mg/L of short chain fatty acids produced by Streptomyces albus J1074 harboring these engineered PKSs. Expanding this method to larger intermediates requiring bimodular communication, we introduced reductive loops of divergent chemosimilarity into LipPKS2 and determined triketide lactone production. Collectively, we observed a statistically significant correlation between atom pair chemosimilarity and production, establishing a new chemoinformatic method that may aid in the engineering of PKSs to produce desired, unnatural products.

biochemistry↗