MARCHADIER, E. | Search bioRxiv

bioRxiv2024

A moderate water deficit induces profound changes in the proteome of developing maize ovaries

Water deficit is a major cause of yield loss for maize (Zea mays), leading to ovary abortion when applied at flowering time. To help understand the mechanisms involved in this phenomenon, the proteome response to water deficit has been analysed in developing ovaries at silk emergence stage and five days later. Differential analysis, abundance pattern clustering and coexpressions networks were performed in order to draw a general picture of the proteome changes all along ovary development and under the effect of water deficit. The results show that, even mild, water deficit has a major impact on ovary proteome, but that this impact is very different from a response to a stress. A part of the changes can be related to a slowdown of ovary development, while another part cannot. In particular, ovaries submitted to water deficit show an increase in proteins involved in protein biosynthesis and in vesicle transport together with a decrease in proteins involved in amino acid metabolism and proteolysis. According to the functions of increased proteins, the changes may be linked to auxin, brassinosteroids and jasmonate signalling, but not abscisic acid.

plant biology↗

bioRxiv2023

The coupling between mutations effects and environment guides the exploration of the phenotypic space as evidenced in artificial selection experiments

Quantitative genetics models have shown that long-term selection responses depend on initial variance and mutational influx. Understanding limits of selection requires quantifying the role of mutational variance. However, correlative responses to selection on non-focal traits can perturb the selection response on the focal trait; and generations are often confounded with selection environments so that genotype by environment (GxE) interactions are ignored. The Saclay Divergent Selection Experiments (DSE) on maize flowering time were used to track the fate of individual mutations combining genotyping data and phenotyping data from yearly measurements (DSEYM) and common garden experiments (DSECG) with four objectives (1) to quantify the relative contribution of standing and mutational variance to the selection response, (2) to estimate genotypic mutation effects, (3) to study the impact of GxE interactions in the selection response, (4) to analyze how trait correlations modulate the exploration of the phenotypic space. We validated experimentally the expected enrichment of fixed beneficial mutations with an average effect of +0.278 and +0.299 days to flowering, depending on the genetic background. Fixation of unfavorable mutations reached up to 25% of incoming mutations, a genetic load possibly due to antagonistic pleiotropy, whereby mutations fixed in the selection environment (DSEYM) turned to be unfavorable in the evaluation environment (DSECG). Global patterns of trait correlations were conserved across genetic backgrounds but exhibited temporal patterns. Traits weakly or uncorrelated with flowering time triggered stochastic exploration of the phenotypic space, owing to microenvironment-specific fixation of standing variants and pleiotropic mutational input.

evolutionary biology↗