Dataset Information

Priming Maritime Pine Megagametophytes during Somatic Embryogenesis Improved Plant Adaptation to Heat Stress.

ABSTRACT: In the context of global climate change, forest tree research should be addressed to provide genotypes with increased resilience to high temperature events. These improved plants can be obtained by heat priming during somatic embryogenesis (SE), which would produce an epigenetic-mediated transgenerational memory. Thereby, we applied 37 °C or 50 °C to maritime pine (Pinus pinaster) megagametophytes and the obtained embryogenic masses went through the subsequent SE phases to produce plants that were further subjected to heat stress conditions. A putative transcription factor WRKY11 was upregulated in priming-derived embryonal masses, and also in the regenerated P37 and P50 plants, suggesting its role in establishing an epigenetic memory in this plant species. In vitro-grown P50 plants also showed higher cytokinin content and SOD upregulation, which points to a better responsiveness to heat stress. Heat exposure of two-year-old maritime pine plants induced upregulation of HSP70 in those derived from primed embryogenic masses, that also showed better osmotic adjustment and higher increases in chlorophyll, soluble sugars and starch contents. Moreover, ϕPSII of P50 plants was less affected by heat exposure. Thus, our results suggest that priming at 50 °C at the SE induction phase is a promising strategy to improve heat resilience in maritime pine.

SUBMITTER: Perez-Oliver MA

PROVIDER: S-EPMC7996847 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Priming Maritime Pine Megagametophytes during Somatic Embryogenesis Improved Plant Adaptation to Heat Stress.

Pérez-Oliver María Amparo MA Haro Juan Gregorio JG Pavlović Iva I Novák Ondřej O Segura Juan J Sales Ester E Arrillaga Isabel I

Plants (Basel, Switzerland) 20210226 3

In the context of global climate change, forest tree research should be addressed to provide genotypes with increased resilience to high temperature events. These improved plants can be obtained by heat priming during somatic embryogenesis (SE), which would produce an epigenetic-mediated transgenerational memory. Thereby, we applied 37 °C or 50 °C to maritime pine (<i>Pinus pinaster</i>) megagametophytes and the obtained embryogenic masses went through the subsequent SE phases to produce plants ...[more]

PMID: 33652929

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Project description:Maritime pine (Pinus pinaster Aiton) is a coniferous native of the Mediterranean basin. Because of its adaptability to a wide range of environmental conditions, the species have become a model for studies in coniferous forest management and functional genomics. Somatic embryogenesis (SE) has been so far, the preferred biotechnological strategy for maritime pine breeding programs initiated at the middle-end of the 20th century. To overcome the limitations of the induction and maturation phases in maritime pine SE, we analyzed the possible maternal influence on the embryogenic capability of megagametophytes from controlled crosses, as well as the effect of the temperature and water availability during SE process on the production of plants. A strong maternal effect on the embryogenic potential of maritime pine megagametophytes was observed in our experiments using half-sib and full-sib progenies, while paternal effect was almost undetectable. Besides, it seems possible to improve somatic embryo production of maritime pine megagametophytes by adjusting optimal temperature throughout the process: 28°C during induction and proliferation, and 23°C during the maturation phase. Using induction and proliferation media with reduced water availability (6 g/L Gelrite) can also increase embryo production. Since other limitation of maritime pine SE is culture decline of embryogenic masses (EMs), that reduces embryo yield and germination, we assessed the profile of ABA and IAA and the expression of two embryogenesis-related genes (LEC1 and WOX2) during maturation of EMs of two morphotypes that differed in their maturation capability. Spiky morphotype (SK), with high maturation capability, had a steady increase in both hormones along the 12 weeks of the maturation, whereas ABA content in smooth morphotype picked at the 4th week and dropped. EMs with this morphotype also had a higher IAA content at the beginning of the maturation. A decrease of LEC1 and WOX2 gene expression over the course of embryo development was found to be characteristic of the SK with high maturation capability.

Project description:The significant morphological differences observed during embryo development in angiosperms and gymnosperms are expected to be the result of a differential control of gene expression. We used a loblolly pine (Pinus taeda) cDNA microarray to analyze global transcriptional changes along zygotic embryogenesis in maritime pine (Pinus pinaster). A time-course analysis of the data obtained from the five embryo developmental groups used in this study led to the identification of 4,645 genes whose expression varied along P. pinaster embryogenesis. These transcripts were clustered into six distinct expression profiles. The grouping of these profiles in early, mid-embryogenesis and embryo maturation, according to the developmental period where most of the sequences were up-regulated, evidenced that characteristic transcriptional changes are associated to each developmental period. The application of a cut-off value of 1.95-fold change led to the identification of 1,838 differentially expressed transcripts that were categorized by biological process. Metabolism, interaction with the environment, oxidation-reduction and transport were some of the most represented categories. During early embryogenesis genes putatively involved in phytohormone-mediated signaling were identified, whereas in middle stages the overrepresented genes could be associated with cotyledon formation and induction of somatic embryogenesis. Genes associated with the synthesis of storage products were up-regulated in the latest stages of pine embryo development. It was also during this developmental period that the largest number of sequences putatively encoding transcription factors was identified. Pine immature zygotic embryos were pooled into five different developmental groups according to the collection date (Day0; Day5; Day11; Day15 and Day25). A common reference design was used. Total RNA was extracted from each sample. Three extractions were prepared per sample (biological replicates). A defined ammount from each RNA sample was pooled to use as reference. Messenger RNA was amplified for both test samples and reference. These were hybridized together in two separate experiments (technical replicates). In total, 30 slides were analyzed.

Project description:Climate change will inevitably lead to environmental variations, thus plant drought tolerance will be a determinant factor in the success of plantations and natural forestry recovery. Some metabolites, such as soluble carbohydrates and amino acids, have been described as being the key to both embryogenesis efficiency and abiotic stress response, contributing to phenotypic plasticity and the adaptive capacity of plants. For this reason, our main objectives were to evaluate if the temperature during embryonal mass initiation in radiata pine was critical to the success of somatic embryogenesis, to alter the morphological and ultrastructural organization of embryonal masses at cellular level and to modify the carbohydrate, protein, or amino acid contents. The first SE initiation experiments were carried out at moderate and high temperatures for periods of different durations prior to transfer to the control temperature of 23°C. Cultures initiated at moderate temperatures (30°C, 4 weeks and 40°C, 4 days) showed significantly lower initiation and proliferation rates than those at the control temperature or pulse treatment at high temperatures (50°C, 5 min). No significant differences were observed either for the percentage of embryogenic cell lines that produced somatic embryos, or for the number of somatic embryos per gram of embryonal mass. Based on the results from the first experiments, initiation was carried out at 40°C 4 h; 50°C, 30 min; and a pulse treatment of 60°C, 5 min. No significant differences were found for the initiation or number of established lines or for the maturation of somatic embryos. However, large morphological differences were observed in the mature somatic embryos. At the same time, changes observed at cellular level suggested that strong heat shock treatments may trigger the programmed cell death of embryogenic cells, leading to an early loss of embryogenic potential, and the formation of supernumerary suspensor cells. Finally, among all the differences observed in the metabolic profile, it is worth highlighting the accumulation of tyrosine and isoleucine, both amino acids involved in the synthesis of abiotic stress response-related secondary metabolites.

Dataset Information

Priming Maritime Pine Megagametophytes during Somatic Embryogenesis Improved Plant Adaptation to Heat Stress.

Publications

Priming Maritime Pine Megagametophytes during Somatic Embryogenesis Improved Plant Adaptation to Heat Stress.

Similar Datasets

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