Belen, F. | Search bioRxiv

bioRxiv2025

Maize mutant hybrids with improved drought tolerance and increased yield in a field experimental setting

Previous studies determined that maize mutants in miR394-regulated genes, ZmLCR1 and ZmLCR2, are more tolerant than wild-type seedlings to prolonged periods of drought. In order to evaluate the effect of these mutations in a genetic background more similar to that of maize commercialization, in this work we evaluate growth of double mutant hybrid plants in W22/B73 genetic background and also evaluated plant fitness, flowering and yield in experimental plots under two watering regimes, and compared the nutritional content of wild-type and mutant hybrids. Our results show that mutant hybrid seedlings exhibit improved physiology under normal watering conditions as well as in drought conditions, exhibiting an increase in epicuticular wax content, unaltered membrane damage in drought and lower ROS production, supporting higher survival after severe drought for double mutant hybrid seedlings. We also established that the hybrid mutants grown in typical agricultural conditions do not show differences in flowering time or in physiological and nutritional aspects, but they present a higher yield in comparison to wild-type W22/B73 hybrids, as determined by higher ear weight and number of kernels per ear in mutant hybrids, when grown in field rainfed conditions. HighlightsO_LIDouble mutants in miR394-regulated genes, ZmLCR1 and ZmLCR2, show enhanced drought tolerance in hybrid maize seedlings, with improved physiological traits under both normal and stress conditions. C_LIO_LIMutant hybrids exhibit increased epicuticular wax accumulation and reduced ROS production, supporting greater survival during prolonged drought stress. C_LIO_LIField-grown mutant hybrids in a W22/B73 background maintain normal flowering time and nutritional composition, indicating no agronomic penalties from the mutations. C_LIO_LIYield is significantly higher in mutant hybrids compared to wild-type controls, as shown by increased ear weight and kernel number under rainfed field conditions. C_LIO_LIThese findings highlight ZmLCR1 and ZmLCR2 as valuable targets for breeding drought-tolerant, high-yielding maize cultivars suited to production environments. C_LI

plant biology↗

bioRxiv2025

Transcriptomic insights into the role of miR394 in the regulation of flowering time in Arabidopsis thaliana

The initiation of flowering is a highly coordinated process that requires synchronization of endogenous plant developmental program with environmental signals through a complex interplay of genetic regulatory networks. The developmental shift from vegetative to reproductive stage is controlled by multiple flowering pathways, which together with other signals participate in the orchestration of flowering time regulation. Collectively, the different pathways converge to modulate the expression of key floral integrator genes, which subsequently trigger the expression of genes related to the differentiation of the vegetative shoot apical meristem into a flower meristem with the subsequent development of floral organs. We had previously demonstrated a role for miR394 in the regulation of flowering time, since mir394a mir394b double mutant plants harboring T-DNA insertions in the two MIR394 Arabidopsis genes exhibited an early flowering phenotype correlated with modified expression of flowering genes. In the present study we provide transcriptomic data and histological staining of reporter lines to give further insight into the role of miR394 in the regulation of flowering time in Arabidopsis thaliana and present an initial bioinformatic characterization of a newly identified lncRNA, which is found partially overlapping the MIR394B locus, and therefore we named MIR394B-ASSOCIATED TRANSCRIPT (MIRAST). We identified differential domains of expression during flower development, which together with the transcriptomic analysis allows us to propose a role for miR394 in the fine tuning of Arabidopsis flower development through the regulation of transcription factors and chromatin remodeling factors. Key messageDifferential domains of activity of MIR394A and MIR394B gene promoters together with transcriptomic analysis of mutant plants, indicate that miR394 participates in the fine tuning of Arabidopsis flower development through regulation of transcription factors and chromatin remodeling factors.

plant biology↗