Browsing by Author "Dijkwel PP"

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    Comparative Transcriptomics of Multi-Stress Responses in Pachycladon cheesemanii and Arabidopsis thaliana.
    (MDPI (Basel, Switzerland), 2023-07-11) Dong Y; Gupta S; Wargent JJ; Putterill J; Macknight RC; Gechev TS; Mueller-Roeber B; Dijkwel PP; You FM
    The environment is seldom optimal for plant growth and changes in abiotic and biotic signals, including temperature, water availability, radiation and pests, induce plant responses to optimise survival. The New Zealand native plant species and close relative to Arabidopsis thaliana, Pachycladon cheesemanii, grows under environmental conditions that are unsustainable for many plant species. Here, we compare the responses of both species to different stressors (low temperature, salt and UV-B radiation) to help understand how P. cheesemanii can grow in such harsh environments. The stress transcriptomes were determined and comparative transcriptome and network analyses discovered similar and unique responses within species, and between the two plant species. A number of widely studied plant stress processes were highly conserved in A. thaliana and P. cheesemanii. However, in response to cold stress, Gene Ontology terms related to glycosinolate metabolism were only enriched in P. cheesemanii. Salt stress was associated with alteration of the cuticle and proline biosynthesis in A. thaliana and P. cheesemanii, respectively. Anthocyanin production may be a more important strategy to contribute to the UV-B radiation tolerance in P. cheesemanii. These results allowed us to define broad stress response pathways in A. thaliana and P. cheesemanii and suggested that regulation of glycosinolate, proline and anthocyanin metabolism are strategies that help mitigate environmental stress.
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    Comparison of leaf senescence regulation between distantly related plant species uncovers knowledge gaps and opportunities for plant improvement strategies
    (Elsevier B.V., 2023-10-01) Aloryi KD; Jing H-C; Dijkwel PP
    Leaf senescence is a destructive process that allows the efficient recycling of nutrients from dying leaves to growing parts of the plant. It is the final stage of leaf development that can be induced in response to stress. This makes leaf senescence an adaptive process that is highly beneficial for whole plant survival under unpredictable environmental conditions. Thus, the manipulation of this process has the potential to improve crop plants to become more climate resilient. In this review we compare leaf senescence processes between distantly related species to identify knowledge gaps and opportunities for plant improvement strategies. We describe that main signalling pathways controlled by carbohydrates, reactive oxygen species and hormones are conserved. However, the role of ethylene in age-induced leaf senescence in cereals is obscure. Moreover, downstream senescence regulatory signalling events are largely unknown, and these may be considerably different between members of annual dicots and cereals. Because leaf senescence regulation is so intricately connected to basic metabolic and developmental processes, we propose to increase research efforts to discover natural variation in senescence regulation and pinpoint gene variants that are tried and tested in nature.
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    Developmentally controlled changes during Arabidopsis leaf development indicate causes for loss of stress tolerance with age
    (Oxford University Press on behalf of the Society for Experimental Biology, 2020-10-22) Kanojia A; Gupta S; Benina M; Fernie AR; Mueller-Roeber B; Gechev T; Dijkwel PP; Foyer C
    Leaf senescence is the final stage of leaf development and is induced by the gradual occurrence of age-related changes (ARCs). The process of leaf senescence has been well described, but the cellular events leading to this process are still poorly understood. By analysis of progressively ageing, but not yet senescing, Arabidopsis thaliana rosette leaves, we aimed to better understand processes occurring prior to the onset of senescence. Using gene expression analysis, we found that as leaves mature, genes responding to oxidative stress and genes involved in stress hormone biosynthesis and signalling were up-regulated. A decrease in primary metabolites that provide protection against oxidative stress was a possible explanation for the increased stress signature. The gene expression and metabolomics changes occurred concomitantly to a decrease in drought, salinity, and dark stress tolerance of individual leaves. Importantly, stress-related genes showed elevated expression in the early ageing mutant old5 and decreased expression in the delayed ageing mutant ore9. We propose that the decreased stress tolerance with age results from the occurrence of senescence-inducing ARCs that is integrated into the leaf developmental programme, and that this ensures a timely and certain death.
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    Genome-Wide Analysis of BBX Gene Family in Three Medicago Species Provides Insights into Expression Patterns under Hormonal and Salt Stresses.
    (MDPI (Basel, Switzerland), 2024-05-26) Wang J; Meng Z; He H; Du P; Dijkwel PP; Shi S; Li H; Xie Q; Igamberdiev AU
    BBX protein is a class of zinc finger transcription factors that have B-box domains at the N-terminus, and some of these proteins contain a CCT domain at the C-terminus. It plays an important role in plant growth, development, and metabolism. However, the expression pattern of BBX genes in alfalfa under hormonal and salt stresses is still unclear. In this study, we identified a total of 125 BBX gene family members by the available Medicago reference genome in diploid alfalfa (Medicago sativa spp. Caerulea), a model plant (M. truncatula), and tetraploid alfalfa (M. sativa), and divided these members into five subfamilies. We found that the conserved motifs of BBXs of the same subfamily reveal similarities. We analyzed the collinearity relationship and duplication mode of these BBX genes and found that the expression pattern of BBX genes is specific in different tissues. Analysis of the available transcriptome data suggests that some members of the BBX gene family are involved in multiple abiotic stress responses, and the highly expressed genes are often clustered together. Furthermore, we identified different expression patterns of some BBX genes under salt, ethylene, salt and ethylene, salicylic acid, and salt and salicylic acid treatments, verified by qRT-PCR, and analyzed the subcellular localization of MsBBX2, MsBBX17, and MsBBX32 using transient expression in tobacco. The results showed that BBX genes were localized in the nucleus. This study systematically analyzed the BBX gene family in Medicago plants, which provides a basis for the study of BBX gene family tolerance to abiotic stresses.
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    Genome-Wide Analysis of the SRPP/REF Gene Family in Taraxacum kok-saghyz Provides Insights into Its Expression Patterns in Response to Ethylene and Methyl Jasmonate Treatments.
    (MDPI (Basel, Switzerland), 2024-07-07) He H; Wang J; Meng Z; Dijkwel PP; Du P; Shi S; Dong Y; Li H; Xie Q; Pollmann S
    Taraxacum kok-saghyz (TKS) is a model plant and a potential rubber-producing crop for the study of natural rubber (NR) biosynthesis. The precise analysis of the NR biosynthesis mechanism is an important theoretical basis for improving rubber yield. The small rubber particle protein (SRPP) and rubber elongation factor (REF) are located in the membrane of rubber particles and play crucial roles in rubber biosynthesis. However, the specific functions of the SRPP/REF gene family in the rubber biosynthesis mechanism have not been fully resolved. In this study, we performed a genome-wide identification of the 10 TkSRPP and 2 TkREF genes' family members of Russian dandelion and a comprehensive investigation on the evolution of the ethylene/methyl jasmonate-induced expression of the SRPP/REF gene family in TKS. Based on phylogenetic analysis, 12 TkSRPP/REFs proteins were divided into five subclades. Our study revealed one functional domain and 10 motifs in these proteins. The SRPP/REF protein sequences all contain typical REF structural domains and belong to the same superfamily. Members of this family are most closely related to the orthologous species T. mongolicum and share the same distribution pattern of SRPP/REF genes in T. mongolicum and L. sativa, both of which belong to the family Asteraceae. Collinearity analysis showed that segmental duplication events played a key role in the expansion of the TkSRPP/REFs gene family. The expression levels of most TkSRPP/REF members were significantly increased in different tissues of T. kok-saghyz after induction with ethylene and methyl jasmonate. These results will provide a theoretical basis for the selection of candidate genes for the molecular breeding of T. kok-saghyz and the precise resolution of the mechanism of natural rubber production.
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    Primary metabolic processes as drivers of leaf ageing
    (Springer Nature Switzerland AG, 2021-10) Kanojia A; Shrestha DK; Dijkwel PP
    Ageing in plants is a highly coordinated and complex process that starts with the birth of the plant or plant organ and ends with its death. A vivid manifestation of the final stage of leaf ageing is exemplified by the autumn colours of deciduous trees. Over the past decades, technological advances have allowed plant ageing to be studied on a systems biology level, by means of multi-omics approaches. Here, we review some of these studies and argue that these provide strong support for basic metabolic processes as drivers for ageing. In particular, core cellular processes that control the metabolism of chlorophyll, amino acids, sugars, DNA and reactive oxygen species correlate with leaf ageing. However, while multi-omics studies excel at identifying correlative processes and pathways, molecular genetic approaches can provide proof that such processes and pathways control ageing, by means of knock-out and ectopic expression of predicted regulatory genes. Therefore, we also review historic and current molecular evidence to directly test the hypotheses unveiled by the systems biology approaches. We found that the molecular genetic approaches, by and large, confirm the multi-omics-derived hypotheses with notable exceptions, where there is scant evidence that chlorophyll and DNA metabolism are important drivers of leaf ageing. We present a model that summarises the core cellular processes that drive leaf ageing and propose that developmental processes are tightly linked to primary metabolism to inevitably lead to ageing and death.
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    The complete chloroplast genome of the first registered Paeonia Itoh hybrid cv. Hexie in China.
    (Taylor and Francis Group, 2024-06-24) Duan S; Dai R; Hao M; Shrestha DK; Dijkwel PP; Gao K; Wu J; Fan B
    The first registered Paeonia Itoh hybrid cv. Hexie in China is a naturally occurring intersectional hybrid of Sect. Paeonia and Sect. Moutan. In this study, we sequenced, assembled, and analyzed the complete chloroplast genome of Paeonia Itoh hybrid cv. Hexie. The result showed that the chloroplast genome of Hexie, with a typical circular tetrad structure, is 152,958 bp in length, comprising a large single copy (LSC) region of 84,613 bp, a small single copy (SSC) region of 17,051 bp, and two reverse complementary sequences (IRs) of 25,647 bp. The chloroplast genome encoded 116 genes, including 80 protein-coding genes, 32 tRNA genes, and 4 rRNA genes. Phylogenetic analysis inferred from the shared protein-coding genes showed that the Paeonia Itoh hybrid cv. Hexie had the closest phylogenetic relationship with P. suffruticosa, followed by P. ostii, indicating that P. suffruticosa was its maternal parent. This study provides a molecular resource for phylogenetic and maternal parent studies of Paeonia Itoh hybrid, contributing to a basis for Paeonia Itoh hybrid breeding strategies in the future.