Biology subjects

Fleming, A. J.

Publications and source records attributed to Fleming, A. J..

6 recordsLinked to original sources

bioRxiv2025

The cellular architecture of wheat leaves supports a conservation of spatial patterning of the mesophyll in grasses

Classical botany identifies a clear adaxial/abaxial (palisade/spongy) patterning of the mesophyll in leaves of eudicots but suggest that there is no comparable overt pattern within the mesophyll of most grasses. In this paper, we report on an analysis of leaves from across ploidy levels of Triticum species which reveals a patterning of mesophyll cellular architecture that has been maintained during the evolution/selection of wheat. Taking a quantitative approach to the analysis of 2D and 3D images, we show that upper and lower mesophyll cells are larger than the middle mesophyll cells, which are themselves more lobed than the mesophyll cells adjoining the upper and lower epidermis. This mesophyll patterning is superimposed on a gradual increase of cell size with ploidy, suggesting that it is evolutionarily ancient. Taken in the context of data revealing patterning of the rice mesophyll, our data support the hypothesis that grass leaves do display distinct cellular patterning across the adaxial/abaxial axis, the functional significance of which awaits full elucidation.

plant biology↗

bioRxiv2024

Identification of Gene Targets for the Sprouting Inhibitor CIPC

Sprout suppressants are widely used in industry to ensure year-round availability of potato tubers, significantly decreasing wastage by repressing premature growth of buds on the tuber surface during storage. Despite its ban from 2020 in the EU, isopropyl N-(3- chlorophenyl) carbamate (also known as chlorpropham or CIPC) remains the most widely used suppressant world-wide. However, the mechanism of action of CIPC remains obscure. Here we report on a combined targeted transcriptomic and genetic approach to identify components in the tuber bud cell-division machinery that might be involved in CIPCs mode of action. This involved RNAseq analysis of dissected, staged tuber buds during in vitro sprouting with and without CIPC to identify lead genes, followed by the development and application of an Arabidopsis root assay to assess cell division response to CIPC in selected mutants. The ease of use of this model plant, coupled with its immense genetic resources, allowed us to test the functionality of lead genes encoding cell-division associated proteins in the modulation of plant growth response to CIPC. This approach led to the identification of a component of the augmin complex (a core player in mitosis) as a potential target for CIPC.

plant biology↗

bioRxiv2023

A regulatory circuit involving the NADH dehydrogenase-like complex balances C4 photosynthetic carbon flow and cellular redox in maize

O_LIC4 plants typically operate a CO2 concentration mechanism from mesophyll (M) cells into bundle sheath (BS) cells. NADH dehydrogenase-like (NDH) complex is enriched in the BS cells of many NADP-ME type C4 plants, and is more abundant in C4 than in C3 plants, but to what extent it is involved in the CO2 concentration mechanism remains to be experimentally investigated. C_LIO_LIWe created maize and rice mutants deficient in NDH function, and used a combination of transcriptomic, proteomic, and metabolomic approaches for comparative analysis. C_LIO_LIConsiderable decrease in growth, photosynthetic activities, and levels of key photosynthetic proteins were observed in maize but not rice mutants. However, gene expression for many cyclic electron transport and Calvin-Benson cycle components plus BS specific C4 enzymes, was up-regulated in maize mutants. Metabolite analysis of the maize ndh mutants revealed increased NADPH/NADP ratio, as well as malate, RuBP, FBP, and photorespiration components. C_LIO_LIWe suggest that by optimizing NADPH and malate levels, adjusting NADP-ME activity, NDH functions to balance metabolic and redox states in the BS cells of maize, coordinating photosynthetic gene expression and protein content, thus directly regulating the carbon flow in the two-celled C4 system of maize. C_LI

plant biology↗

bioRxiv2022

Stomatal density affects rice mesophyll cell size and shape and modulates a conserved pattern of cells through the leaf

The structure of the mesophyll influences how light, CO2 and water travels inside a leaf, affecting the rates of both photosynthesis and transpiration. Recent studies in wheat and Arabidopsis have shown that the structure of the mesophyll is influenced by the density and activity of stomata, consistent with the hypothesis that gas flow via stomata can modulate internal cell growth and separation to co-ordinate leaf structure and function. To investigate whether this also occurs in rice, a staple food crop for a large fraction of the worlds population, we examined mesophyll structure in rice mutants with altered stomatal density. Our data show that stomatal function modulates mesophyll structure in rice. Variation in the degree of mesophyll lobing made a major contribution to altered mesophyll structure, suggesting that modified leaf gas flux through stomata influences an aspect of cell shape directly linked to gas exchange capacity in rice. In addition, our analysis revealed a previously unreported underlying pattern in cell size, shape and axiality across layers of the rice mesophyll, which further investigation revealed is present in a range of rice species and cultivars. The potential origin and significance of this mesophyll patterning are discussed. HIGHLIGHTWe describe a previously unreported cellular pattern in rice leaves and show that it is modulated by stomata. These results shed new light on leaf structure and function.

plant biology↗

bioRxiv2021

Rice leaves undergo a rapid metabolic reconfiguration during a specific stage of primordium development

Leaf development is crucial to establish the photosynthetic competency of plants. It is a process that requires coordinated changes in cell number and differentiation, transcriptomes, metabolomes and physiology. However, despite the importance of leaf formation for our major crops, early developmental processes for rice have not been comprehensively described. Here we detail the temporal developmental trajectory of early rice leaf development and connect morphological changes to metabolism. In particular, a developmental index based on the patterning of epidermal differentiation visualised by electron microscopy enabled high resolution staging of early growth for single primordium metabolite profiling. These data demonstrate that a switch in the constellation of tricarboxylic acid (TCA) cycle metabolites defines a narrow window towards the end of the P3 stage of leaf development. Taken in the context of other data in the literature, our results substantiate that this phase of rice leaf growth, equivalent to a change of primordium length from around 5 to 7.5 mm, defines a major shift in rice leaf determination towards a photosynthetically defined structure. We speculate that efforts to engineer rice leaf structure should focus on the developmental window prior to these determining events. HighlightRice leaves undergo a shift in fundamental metabolism during a very early and narrow developmental window which co-incides with them acquiring the ability to capture light for photosynthesis

plant biology↗

bioRxiv2020

Genetic screen to saturate guard cell signaling network reveals a role of GDP-L-fucose metabolism in stomatal closure

Guard cells regulate plant gas exchange by controlling the aperture of stomatal pores. The process of stomatal closure involves a multi-input signaling network that governs the activity of ion channels, which in turn regulate guard cell turgor pressure and volume. Here we describe a forward genetic screen to identify novel components involved in stomatal movements. Through an ozone-sensitivity approach combined with whole-rosette gas exchange analysis, 130 mutants of established stomatal regulators and 76 novel mutants impaired in stomatal closure were identified. One of the novel mutants was mapped to MURUS1 (MUR1), the first enzyme in de novo GDP-L-fucose biosynthesis. Defects in synthesis or import of GDP-L-Fuc into the Golgi apparatus resulted in impaired stomatal closure to multiple stimuli. Stomatal phenotypes observed in mur1 were independent from the canonical guard cell signaling and instead could be related to altered mechanical properties of guard cell walls. Impaired fucosylation of xyloglucan, N-linked glycans and arabinogalactan proteins did not explain the aberrant function of mur1 stomata, however our data suggest that the stomatal phenotypes observed in mur1 can at least partially be attributed to defective dimerization of rhamnogalactouronan-II. In addition to providing the genetic framework for future studies on guard cell signaling, our work emphasizes the impact of fucose metabolism on stomatal movement.

plant biology↗