Biology subjects

Reeves, G.

Publications and source records attributed to Reeves, G..

4 recordsLinked to original sources

bioRxiv2024

Identifying Agronomic, Nutrition and Leaf Vein Quantitative Trait Loci in the Orphan Crop Gynandropsis gynandra

A sustainable food supply is vital for addressing the challenges of a growing global population and climate change. Gynandropsis gynandra, a nutritious C4 orphan crop native to Africa and Asia, thrives in low-input agricultural systems, making it a valuable candidate for future food security. This crop also serves as a model for studying C4 photosynthesis. However, research on its genetic improvement is limited. In this study, two mapping populations from diverse parental lines were used to identify Quantitative Trait Loci (QTL) linked to agronomically relevant traits like plant height, leaf area, flowering time, nutritional content, and photosynthesis. Fifteen QTL were identified, with two affecting both leaf size and flowering time across populations, which can be applied for marker assisted selection for crop improvement. Additionally, QTL linked to C4 photosynthesis provide insights into the genetic mechanisms behind this pathway. Overall, this research enhances the potential of G. gynandra as a climate-resilient crop. One sentence summaryLeveraging natural variation in Gynandropsis gynandra to identify QTL associated with important traits.

plant biology↗

bioRxiv2020

Upregulation and cell specificity of C4 genes are derived from ancestral C3 gene regulatory networks

C4 photosynthesis has evolved independently in over sixty lineages and in so doing repurposed existing enzymes to drive a carbon pump that limits the RuBisCO oxygenation reaction. In all cases, gene expression is modified such that C4 proteins accumulate to levels matching those of the photosynthetic apparatus. To better understand this rewiring of gene expression we undertook RNA- and DNaseI-SEQ on de-etiolating seedlings of C4 Gynandropsis gynandra, which is sister to C3 Arabidopsis. Changes in chloroplast ultrastructure and C4 gene expression were coordinated and rapid. C3 photosynthesis and C4 genes showed similar induction patterns, but C4 genes from G. gynandra were more strongly induced than orthologs from Arabidopsis. A gene regulatory network predicted transcription factors operating at the top of the de-etiolation network, including those responding to light, act upstream of C4 genes. Light responsive elements, especially G-, E- and GT-boxes were over-represented in accessible chromatin around C4 genes. Moreover, in vivo binding of many G-, E- and GT-boxes was detected. Overall, the data support a model in which rapid and robust C4 gene expression following light exposure is generated through modifications in cis to allow integration into high-level transcriptional networks including those underpinned by conserved light responsive elements.

plant biology↗

bioRxiv2018

Dorsal/NF-κB exhibits a dorsal-to-ventral mobility gradient in the Drosophila embryo

Morphogen-mediated patterning is a highly dynamic developmental process. To obtain an accurate understanding of morphogen gradient formation and downstream gene expression, biophysical parameters such as protein mobilities must be quantified in vivo. The dorsal-ventral (DV) patterning of early Drosophila embryos by the NF-{kappa}B homolog Dorsal (Dl) is an excellent system for understanding morphogen gradient formation. Dl gradient formation is controlled by the inhibitor Cactus/I{kappa}B (Cact), which regulates the nuclear import and diffusion of Dl protein. However, quantitative measurements of Dl mobility and binding are currently lacking. Here, we use scanning fluorescence correlation spectroscopy to quantify the mobility of GFP-tagged Dl. We find that the DNA binding of Dl-GFP, which affects its mobility, varies along the DV axis, with highest DNA binding on the ventral side. Moreover, we also observe that the time scale for Dl-GFP to exit the nucleus is longer in the ventral and lateral regions of the embryo, which is consistent with stronger DNA binding. Using analysis of mutant alleles of dl tagged with GFP, we conclude that Dl-GFP/Cact interactions in the nuclei are responsible for the variation in Dl-GFP/DNA binding along the DV axis, which impacts our understanding of the spatial range of the Dl gradient and the robustness and precision of downstream gene expression. Thus, our results highlight the complexity of morphogen gradient dynamics and the ability of quantitative measurements of biophysical interactions to drive biological discovery.

developmental biology↗

bioRxiv2018

Quantitative variation within a species for traits underpinning C4 photosynthesis

Engineering C4 photosynthesis into C3 crops such as rice or wheat could substantially increase their yield by alleviating photorespiratory losses1,2. This objective is challenging because the C4 pathway involves complex modifications to the biochemistry, cell biology and anatomy of leaves3. Forward genetics has provided limited insight into the mechanistic basis of these characteristics and there have been no reports of significant quantitative intra-specific variation of C4 attributes that would allow trait-mapping4,5. Here we show that accessions of C4 Gynandropsis gynandra collected from locations across Africa and Asia exhibit natural variation in key characteristics of C4 photosynthesis. Variable traits include bundle sheath size and vein density, gas exchange parameters and carbon-isotope discrimination associated with the C4 state, but also abundance of transcripts encoding core enzymes of the C4 cycle. Traits relating to water use showed more quantitative variation than those associated with carbon assimilation. We propose variation in these traits likely adapted the hydraulic system for increased water use efficiency rather than improving carbon fixation, indicating that selection pressure may drive C4 diversity in G. gynandra by acting to modify water use rather than photosynthesis. As these accessions can be easily crossed and produce fertile offspring, our findings indicate that natural variation within a C4 species is sufficiently large to allow genetic-mapping of key anatomical C4 traits and regulators.

plant biology↗