Biology subjects

Braud, M.

Publications and source records attributed to Braud, M..

3 recordsLinked to original sources

bioRxiv2021

High Light and High Temperature Reduce Photosynthesis via Different Mechanisms in the C4 Model Setaria viridis

C4 plants frequently experience damaging high light (HL) and high temperature (HT) conditions in native environments, which reduce growth and yield. However, the mechanisms underlying these stress responses in C4 plants have been under-explored, especially the coordination between mesophyll (M) and bundle sheath (BS) cells. We investigated how the C4 model plant Setaria viridis responded to a four-hour HL or HT treatment at the photosynthetic, transcriptomic, and ultrastructural levels. Although we observed a comparable reduction of photosynthetic efficiency in HL- or HT-treated leaves, detailed analysis of multi-level responses revealed important differences in key pathways and M/BS specificity responding to HL and HT. We provide a systematic analysis of HL and HT responses in S. viridis, reveal different acclimation strategies to these two stresses in C4 plants, discover unique light/temperature responses in C4 plants in comparison to C3 plants, and identify potential targets to improve abiotic stress tolerance in C4 crops.

plant biology↗

bioRxiv2020

Regulatory signatures of drought response in stress resilient Sorghum bicolor

The effects of drought stress can be devastating to crop production worldwide. A grand challenge facing agriculture is development of crop varieties with improved drought resilience through breeding or biotechnology. To accelerate this, a mechanistic understanding is needed of the regulatory networks underlying drought response in crop genomes and the genetic elements that modulate them. Here, we explore the regulatory landscape of sorghum [Sorghum bicolor (L.) Moench] in response to controlled-environment drought stress. Sorghum is a C4 cereal crop with innate drought resilience. To define molecular signatures of drought response, we mapped genome-wide chromatin accessibility using an Assay for Transposase Accessible Chromatin by sequencing and analyzed parallel transcriptional profiles in drought-stressed sorghum shoot and root tissues. Drought-responsive changes in accessibility were largely in proximal promoters of differentially expressed genes and also in distal regions. Data were integrated to infer gene network connections and cis-regulatory modules underlying drought response and the transcription factors that control them. Inspection of pan-genomic data and phenotyping across sorghum diversity revealed variation in genomic signatures that associated with water use efficiency. Our analyses provide drought-inducible regulatory modules in sorghum that can be leveraged for fine-tuning responses to stress, mining for advantageous alleles, and translating across species.

plant biology↗

bioRxiv2020

SvFUL2, an A-class MADS-box transcription factor, is necessary for inflorescence determinacy in model panicoid cereal, Setaria viridis

Inflorescence architecture in cereal crops directly impacts yield potential through regulation of seed number and harvesting ability. Extensive architectural diversity found in inflorescences of grass species is due to spatial and temporal activity and determinacy of meristems, which control the number and arrangement of branches and flowers, and underlie plasticity. Timing of the floral transition is also intimately associated with inflorescence development and architecture, yet little is known about the intersecting pathways and how they are rewired during development. Here, we show that a single mutation in a gene encoding an AP1 A-class MADS-box transcription factor significantly delays flowering time and disrupts multiple levels of meristem determinacy in panicles of the C4 model panicoid grass, Setaria viridis. Previous reports of A-class genes in cereals have revealed extensive functional redundancy, and in panicoid grasses, no associated inflorescence phenotypes have been described. In S. viridis, perturbation of SvFul2, both through chemical mutagenesis and CRISPR/Cas9-based gene editing, converted a normally determinate inflorescence habit to an indeterminate one, and also repressed determinacy in axillary branch and floral meristems. Our analysis of gene networks connected to disruption of SvFul2 identified regulatory hubs at the intersect of floral transition and inflorescence determinacy, providing insights into the optimization of cereal crop architecture.

plant biology↗