Biology subjects

Napier, J.

Publications and source records attributed to Napier, J..

2 recordsLinked to original sources

bioRxiv2022

The palisade-specific gene IQD22 enhances photosynthetic capacity by phenocopying sun leaf architecture

The world requires a rise in crop production which needs to be increased significantly in order to satisfy demand by 20501. However traditional plant breeding approaches are anticipated to fall short in delivering the increases in yield required and therefore targeted manipulation of plant metabolism is increasingly being pursued with the aim to achieve this goal2. Improving photosynthetic efficiency is predicted to have a significant influence on enhancing crop productivity and several ambitious genetic engineering projects are currently under way to achieve higher photosynthetic rates in crops3,4. A naturally evolved adaptive trait which allows plants to increase photosynthetic efficiency specifically under high light is the differentiation of sun leaves which are characterised by an increase in palisade cell layers and more elongated cells within this layer5. These morphological changes allow a more efficient distribution of light within the leaf and provide an increased cell surface to which chloroplasts can relocate thereby increasing the capacity for CO up-take6. Here we show that, surprisingly, this complex morphological trait can be phenocopied by the modulation of the expression of a single palisade specific gene, IQD22, in Arabidopsis. Furthermore, we could show that the architectural changes were reflected in an increase of photosynthetic rate of 30%. The simplicity with which we could enhance photosynthesis by phenocopying sun leave traits is in stark contrast to the complex and challenging metabolic engineering approaches currently being pursued.

plant biology↗

bioRxiv2021

A point mutation in the kinase domain of CRK10 leads to xylem vessel collapse and activates defence responses

Cysteine-rich receptor-like kinases (CRKs) are a large family of plasma membrane-bound receptors ubiquitous in higher plants. They are transcriptionally regulated by a wide variety of environmental cues and stresses, however their precise biological roles remain largely unknown. Here we report a novel mutant isolated for the CYSTEINE-RICH RECEPTOR-LIKE KINASE 10 (CRK10) of Arabidopsis thaliana which harbours the substitution of alanine 397 by a threonine in the C-helix of its kinase domain and which we registered as crk10-A397T in the community database. In situ phosphorylation assays with the His-tagged wild type (WT) and crk10-A397T versions of the CRK10 kinase domain revealed that both alleles are active kinases capable of auto-phosphorylation with the newly introduced threonine acting as an additional phosphorylation site in crk10-A397T. Phenotypically the mutant is a dwarf and the analysis of thin cross sections with light and transmission electron microscopy revealed that collapsed xylem vessels in roots and hypocotyls are very likely the cause for this reduction in stature. Transcriptomic analysis of WT and mutant hypocotyls revealed that predominantly biotic and abiotic stress-responsive genes are constitutively up-regulated in the mutant. Root-infection assays with the vascular pathogen Fusarium oxysporum demonstrated that the crk10-A397T mutant has enhanced resistance to this pathogen compared to WT plants. Taken together our results suggest that crk10-A397T is a gain-of-function allele of CRK10 and open up new avenues for the investigation of this elusive receptor-like kinase family.

plant biology↗