Biology subjects

Eastmond, P. J.

Publications and source records attributed to Eastmond, P. J..

10 recordsLinked to original sources

bioRxiv2025

Associative transcriptomics in Brassica napus suggests a role for Arabidopsis Response Regulator orthologs in seedling vigour

Background and AimsOptimal seedling vigour determines successful crop establishment and its ability to overcome abiotic and biotic threats. Seedling vigour is regulated by several different factors, genetic, physiological, environmental, post-harvest storage, making it challenging to fully elucidate. The aim of this study was to dissect the genetic basis of post-germinative seedling traits and its implications in seedling establishment success in Brassica napus. MethodsA B. napus diversity set panel was used to phenotype seedling establishment traits in the soil including days to emergence, days to appearance of first and second true leaves, and days to reach 25% and 50% cotyledon expansion. An associative transcriptomics analysis was performed to identify the genetic factors regulating seedling establishment. Key ResultsThe study of different phenotypic traits highlighted the relevance of scoring more than one trait to determine good performers. Gene expression markers significantly associated with the studied traits were associated with the cytokinin signalling pathway and photomorphogenesis. Gene expression markers for orthologues of Arabidopsis thaliana RESPONSE REGULATOR 4 and 5 (ARR4, ARR5) were significantly associated with days to appearance of second leaf. SUPPRESSOR OF PHYA-105 1 (SPA1) orthologues were associated with cotyledon area, meanwhile ALTERED SEED GERMINATION 7 (ASG7) and PSEUDO-RESPONSE REGULATOR 7 (PRR7) orthologues were associated with days to emergence, suggesting a complex and interconnected regulatory pathway controlling several traits of seedling establishment. ConclusionsThese results uncovered promising genes that appear to work in a complex and interconnected manner controlling several post-germinative seedling traits affecting final seedling establishment speed.

plant biology↗

bioRxiv2023

Ketocarotenoid production in tomato triggers metabolic reprogramming and cellular adaptation: The quest for homeostasis?

Plants are sessile and therefore have developed an extraordinary capacity to adapt to external signals. Here, the focus is on the plasticity of the plant cell to respond to new intracellular cues. Ketocarotenoids are high-value natural red pigments with potent antioxidant activity. In the present study, system level analyses have revealed that the heterologous biosynthesis of ketocarotenoids in tomato initiated a series of cellular and metabolic mechanisms to cope with the formation of metabolites that are non-endogenous to the plant. The broad multilevel changes were linked to, among others, (i) the remodelling of the plastidial membrane, where the synthesis and storage of ketocarotenoids occurs, (ii) the recruiting of core metabolic pathways for the generation of metabolite precursors and energy, and (iii) redox control. The role of the metabolites as regulators of cellular processes shown here, reinforces their pivotal role suggested in the remodelled "central dogma" concept.

systems biology↗

bioRxiv2022

Oil accumulation in leaves driven by a native promoter-gene fusion created using CRISPR/Cas9 mediated genomic deletion

Achieving gain-of-function phenotypes without inserting foreign DNA is an important challenge for plant biotechnologists. Here we show that a gene can be brought under the control of a promoter from an upstream gene by deleting the intervening genomic sequence using dual-guide CRISPR/Cas9. We fuse the promoter of a non-essential photosynthesis-related gene to DIACYLGLYCEROL ACYLTRANSFERASE 2 (DGAT2) to drive oil biosynthesis in leaves of a lipase deficient sugar-dependent 1 mutant. DGAT2 expression is enhanced more than twenty-fold and the triacylglycerol content increases by around thirty-fold. This strategy offers a transgene-free route to engineering gain-of-function traits such as high lipid forage to increase the productivity and sustainability of ruminant farming.

bioengineering↗

bioRxiv2021

Production of human milk fat substitute by engineered strains of Yarrowia lipolytica

Human milk fat has a distinctive stereoisomeric structure where palmitic acid is esterified to the middle (sn-2) position on the glycerol backbone of the triacylglycerol and unsaturated fatty acids to the outer (sn-1/3) positions. This configuration allows for more efficient nutrient absorption in the infant gut. However, the fat used in most infant formulas originates from plants, which tend only to esterify palmitic acid to the sn-1/3 positions. Oleaginous yeasts provide an alternative source of lipids for human nutrition. However, these yeasts also exclude palmitic acid from the sn-2 position of their triacylglycerol. Here we show that Yarrowia lipolytica can be engineered to produce triacylglycerol with more than 60% of the palmitic acid in the sn-2 position, by expression of a lysophosphatidic acid phosphatase with palmitoyl-Coenzyme A specificity, such as LPAAT2 from Chlamydomonas reinhardtii. The engineered Y. lipolytica strains can be cultured on glycerol, glucose, palm oil or a mixture of substrates, under nitrogen limited condition, to produce triacylglycerol with a fatty acid composition that resembles human milk fat, in terms of the major molecular species; palmitic, oleic and linoleic acids. Culture on palm oil or a mixture of glucose and palm oil produced the highest lipid titre in shake flask culture and a triacylglycerol composition that is most similar with human milk fat. Our data show that an oleaginous yeast can be engineered to produce a human milk fat substitute ({beta}-palmitate), that could potentially be used as an ingredient in infant formulas.

bioengineering↗

bioRxiv2021

Bayesian optimisation for yield in high-dimensional trait-space identifies crop ideotypes in Oil Seed Rape

The improvement of crop yield has long been a major breeding target and is increasingly becoming a goal in many areas of plant research. Yield has been shown to be a complex trait, depending on multiple genes, plant architecture and plant-environment interactions. This complexity is frequently reduced by focussing on contributing factors to yield (yield traits). However, a quantitative understanding of the interplay between yield traits, and the effect of these relationships on yield is largely unexplored. Consequently, the extent to which crop varieties achieve their optimal morphology in a given environment and how this impacts on seed yield is unknown. Here we use causal inference to model the hierarchically structured effects of 27 macro and micro yield traits on each other over the course of plant development, and on seed yield in Spring and Winter oilseed rape plants. We perform Bayesian optimisation on the modelled yield potential, identifying the morphology of ideotype plants which are expected to be higher yielding than the existing varieties in the studied panels. We find that existing Spring varieties occupy the optimal regions of trait-space, but that potentially high yielding strategies are unexplored in extant Winter varieties. In addition to concrete recommendations for varietal improvement in oilseed rape, this work provides a novel, general methodological framework for the study of crop breeding as an optimisation problem.

plant biology↗

bioRxiv2021

Plants export 2-monopalmitin and supply both fatty acyl and glyceryl moieties to arbuscular mycorrhizal fungi

Arbuscular mycorrhizal fungi (AMF) rely on their host plants to provide them with fatty acids (FA), but the precise form(s) in which they are supplied is still unclear. Here we show that ectopic expression of the transcription factor REQUIRED FOR ARBUSCULAR MYCORRHIZATION 1 (RAM1) can drive secretion of 2-monoacylglycerols (2MGs) from Medicago truncatula roots and that their main FA moiety is palmitic acid, although myristic acid and stearic acid were also detected. RAM1-dependent 2MG secretion requires the acyl-acyl carrier protein thioesterase FATM, the glycerol-3-phosphate (G3P) acyltransferase RAM2 and the ATP binding cassette transporter STR. Furthermore, 14C glycerol labelling experiments using mycorrhizal M. truncatula roots that are deficient in glycerol kinase, FAD-dependent G3P dehydrogenase and the G3P acyltransferase RAM2 suggest that most of the glyceryl moieties in Rhizophagus irregularis storage lipids are provided by their host plant through the 2MG pathway. Taken together, our data support the hypothesis that the plant exports 2MGs across the peri-arbuscular membrane in mycorrhizal roots and that the AMF receive and utilise both the FA and glyceryl moieties to make their storage lipids.

plant biology↗

bioRxiv2020

Allele Mining in Diverse Accessions of Urochloa and Megathyrsus spp. Tropical Grasses to Improve Forage Quality and Reduce Environmental Impact

The C4 Urochloa spp (syn. Brachiaria) and Megathyrsus maximus (syn. Panicum maximum) are used as pasture for cattle across vast areas in tropical agriculture systems in Africa and South America. A key target for variety improvement is forage quality: enhanced digestibility could decrease amount of land required per unit production and enhanced lipid content could decrease methane emissions from cattle. For these traits, loss-of-function (LOF) alleles in known gene targets are predicted to improve them, making a reverse genetics approach of allele mining feasible. We studied allelic diversity of 20 target genes (11 for digestibility, 9 for lipid content) in 104 accessions selected to represent genetic diversity and ploidy levels of U. brizantha, U. decumbens, U. humidicola, U. ruziziensis and M. maximum. We used RNAseq and then bait-capture DNA-seq to improve gene models in a U. ruziziensis reference genome to assign polymorphisms with high confidence. We found 953 non-synonymous polymorphisms across all genes and accessions; within these, we identified 7 putative LOF alleles with high confidence, including ones in the non-redundant SDP1 and BAHD01 genes present in diploid and tetraploid accessions. These LOF alleles could respectively confer increased lipid content and digestibility if incorporated into a breeding programme. HighlightWe found gene variants in a collection of tropical grasses that could help reduce environmental impact of cattle production.

plant biology↗

bioRxiv2020

Uncovering the ideal plant ideotype for maximising seed yield in Brassica napus

Seed yield is a complex trait for many crop species including oilseed rape (Brassica napus), the second most important oilseed crop worldwide. Studies have focused on the contribution of distinct factors in seed yield such as environmental cues, agronomical practices, growth conditions or specific phenotypic traits at the whole plant level, such as number of pods in a plant. However, in spite of the immense economic importance of oilseeds, none of these studies have comprehensively analysed individual traits and their combined contribution to seed yield. Here, we describe the analysis and contribution of 33 phenotypic traits within a B. napus diversity set population and their trade-offs on seed yield not only at the whole plant level but also the less studied female reproductive traits. Our results revealed that both winter and spring oilseed rape; the two more economically important oilseed rape groups in terms of oil production; were found to share a common dominant reproductive strategy for seed yield. In this strategy the main inflorescence is the principal source of seed yield, producing a good number of ovules, a large number of long pods with a concomitantly high number of seeds per pod. We observed that winter oilseed rape opted for more reproductive strategies than spring oilseed rape, presenting more environmental flexibility to maximise seed yield. Overall, we conclude that, oilseed rape adopts a similar strategy that is key for maximal seed yield and propose an ideal ideotype highlighting crucial phenotypic traits that could be potential targets for breeding. One sentence summaryThe main florescence is the principal source of seed yield in winter and spring oilseed rape, with winter oilseed rape following several reproductive strategies to maximise seed yield.

plant biology↗

bioRxiv2020

Production of the infant formula ingredient 1,3-olein-2-palmitin in Arabidopsis seeds

In human milk fat, palmitic acid (16:0) is esterified to the middle (sn-2 or {beta}) position on the glycerol backbone and oleic acid (18:1) predominantly to the outer positions, giving the triacylglycerol (TG) a distinctive stereoisomeric structure that is believed to assist nutrient absorption in the infant gut. However, the fat used in most infant formulas is derived from plants, which preferentially esterify 16:0 to the outer positions. We have previously showed that the metabolism of the model oilseed Arabidopsis thaliana can be engineered to incorporate 16:0 into the middle position of TG. However, the fatty acyl composition of Arabidopsis seed TG does not mimic human milk, which is rich in both 16:0 and 18:1 and is defined by the high abundance of the TG molecular species 1,3-olein-2-palmitin (OPO). Here we have constructed an Arabidopsis fatty acid biosynthesis 1-1 fatty acid desaturase 2 fatty acid elongase 1 mutant with around 20% 16:0 and ~70% 18:1 in its seeds and we have engineered it to esterify more than 80% of the 16:0 to the middle position of TG, using heterologous expression of the human lysophosphatidic acid acyltransferase isoform AGPAT1, combined with suppression of LYSOPHOSPHATIDIC ACID ACYLTRANSFERASE 2 and PHOSPHATIDYLCHOLINE:DIACYLGLYCEROL CHOLINEPHOSPHOTRANSFERASE. Our data suggest that oilseeds can be engineered to produce TG that is rich in OPO, which is an important structured fat ingredient used in infant formulas.

bioengineering↗

bioRxiv2020

Identification of a Δ11 desaturase from the arbuscular mycorrhizal fungus Rhizophagus irregularis

Arbuscular mycorrhizal fungi are oleaginous organisms and the most abundant fatty acyl moiety usually found in their lipids is palmitvaccenic acid (16:1{Delta}11cis). However, it is not known how this uncommon fatty acid species is made. Here we have cloned two homologs of Lepidopteran fatty acyl-CoenzymeA {Delta}11 desaturases from Rhizophagus irregularis. Both DES1 and DES2 are expressed in intraradicle mycelium and can complement the unsaturated fatty acid-requiring auxotrophic growth phenotype of the Saccharomyces cerevisiae ole1{Delta} mutant. DES1 expression leads almost exclusively to oleic acid (18:1{Delta}9cis) production, whereas DES2 expression results in the production of 16:1{Delta}11cis and vaccenic acid (18:1{Delta}11cis). DES2 therefore encodes a {Delta}11 desaturase that is likely to be responsible for the synthesis of 16:1{Delta}11cis in R. irregularis.

microbiology↗