Biology subjects

Greenland, A.

Publications and source records attributed to Greenland, A..

3 recordsLinked to original sources

bioRxiv2022

Wheat cells show positional responses to invasive Zymoseptoria tritici

The stomatal complex of grasses consists of two guard cells and two adjacent subsidiary cells that cooperate during stomatal closure. Zymoseptoria tritici, the main causal agent of Septoria tritici blotch in wheat, enters the host via stomata. Here we test the hypothesis that the stomatal complex shows focused sub-cellular responses to invading Z. tritici hyphae. We have combined live-cell transmission light microscopy, immunofluorescence and CRS microscopy to identify cell wall modifications triggered by hyphal invasion. Furthermore, we have used confocal fluorescence microscopy and automated quantitative image analysis to assess whether host cells respond to hyphae through spatial redistribution of organelles. We find that subsidiary cells construct papillae that are accurately aligned with hyphal position even when hyphae are occluded by guard cells. These are distinct from those induced by powdery mildew, with callose restricted to a crust that surrounds content with a high-amplitude Raman signal in the CH-band. Peroxisome populations in subsidiary cells show distributions with modes weakly correlated with hyphal position but do not differ significantly between compatible and incompatible interactions. Our data suggest local changes to cell wall architecture and focal accumulation of organelles in subsidiary cells could play roles in crop defence during host leaf penetration by Z. tritici. Molecular strategies to amplify these responses may provide novel routes for crop protection.

plant biology↗

bioRxiv2021

Wheat EARLY FLOWERING3 is a dawn-expressed circadian oscillator component that regulates heading date

Using an eight-parent Multiparent Advanced Generation Inter-Cross (MAGIC) population we investigated how variation at circadian clock-associated genes contributes to the regulation of heading date in UK and European winter wheat varieties. We identified homoeologues of EARLY FLOWERING 3 (ELF3) as candidates for the Earliness per se (Eps) D1 and B1 loci in field conditions. We confirmed that a SNP within the coding region of TaELF3-B1 is a candidate polymorphism underlying the Eps-B1 locus. We found that a reported deletion at the Eps-D1 locus encompassing TaELF3-D1, is instead a novel allele that lies within an introgression region containing an inversion relative to the Chinese Spring D genome. Using T. turgidum cv. Kronos carrying loss of function alleles of TtELF3 we show that ELF3 does regulate heading by demonstrating that the loss of a single ELF3 homoeologue was sufficient to alter heading date. These studies demonstrated that ELF3 forms part of the circadian oscillator but loss of all homoeologues was required to affect circadian rhythms. Similarly, loss of functional LUX ARRHYTHMO (LUX) in T. aestivum, an orthologue of a protein partner of Arabidopsis ELF3, severely disrupted circadian rhythms. ELF3 and LUX transcripts are not co-expressed at dusk suggesting the structure of the wheat circadian oscillator might differ to that of Arabidopsis. Our demonstration that alteration to ELF3 homoeologues can affect heading date separate from effects on the circadian oscillator suggests a role for ELF3 in cereal photoperiodic responses that could be selected for, without pleiotropic deleterious alterations to circadian rhythms.

plant biology↗

bioRxiv2019

cis dominantly explains regulatory divergence between two indica rice genotypes; drought further enhances regulatory differences

Abstract cis and/or trans regulatory divergence within or between related taxa on a genome-wide scale has been largely unexamined in crops, more so, the effect of stress on cis/trans architecture. In this study, the indica genotypes IR64, an elite drought-susceptible lowland variety, and Apo (IR55423-01 or NSIC RC9), a moderate drought-tolerant upland genotype together with their hybrid (IR64 x Apo) were exposed to non- and water-stress conditions. Evidence of cis and/or trans regulatory differences was tested between these two indica rice genotypes. By sequencing (RNA-seq) the parents and their hybrid, we are able to map genes diverging in cis and/or trans factors between the two genotypes. Under non-stress conditions, cis dominantly explains (11.2%) regulatory differences, followed by trans (8.9%). Further analysis showed that water-limiting conditions largely affect trans and cis + trans factors. Between the two inbred lines, Apo appears to exhibit higher expression fold change of genes enriched in "response to stress" and "photosynthesis" under non- and water-stress conditions. On the molecular level, cis and/or trans regulatory divergence explains their genotypic differences and differential drought response. Parent-hybrid RNA-seq has the potential to identify genes diverging in cis and/or trans factors even between intra-sub-specifically related genotypes. By comparing cis/trans landscape under stressed and unstressed conditions, this approach has the ability to assess the impact of drought on gene expression. Computational analysis and association of several drought-yield QTL markers with cis-diverging genes provide converging evidences suggestive of a potential approach to identify trait-associated candidate genes using hybrids and their parents alone. Key Messagecis dominantly explains divergence of two indica rice genotypes, IR64 and Apo under normal conditions while trans and cis + trans regulatory factors are largely affected by drought

plant biology↗