Changes in DNA Methylation in Response to 6-Benzylaminopurine Affect Allele-Specific Gene Expression in Populus Tomentosa

Delineation of the impacts of varying 6-benzylaminopurine concentrations on physiological, biochemical and genetic traits of different olive cultivars under in vitro conditions

Abstract. The plant growth regulator 6-benzylaminopurine (BAP) is an important component of plant nutrient medium with tendency to accelerate physiological, biochemical and molecular processes in woody plants such as olive. To date, limited knowledge is available on the role of BAP in mediating physiological, biochemical and genetic activities in olives under in vitro conditions. To cover this research gap, the current study was conducted with the objective of studying the role of BAP in regulating physiological traits (chlorophyll, CO2 assimilation), antioxidant enzymes (superoxide dismutase, catalase and peroxidase), metabolic contents (starch, sucrose and flavonoids) and gene expression (OeRbcl, OePOD10, OeSOD10, OeCAT7, OeSS4, OeSuSY7, OeF3GT and OeChlH) under varying concentrations (0, 0.5, 1.5 and 2.5 mg L-1) within the provided in vitro conditions. The explants obtained from different olive cultivars ('Leccino', 'Gemlik', 'Moraiolo', 'Arbosana') were cultured on olive medium (OM) provided with different BAP concentrations using a two-factorial design, and data were analysed statistically. All traits increased significantly under in vitro conditions due to increasing concentrations of BAP; however, this increase was more dramatic at 2.5 mg L-1 and the least dramatic at 0.5 mg L-1. Moreover, correlation, principal component analysis and heatmap cluster analysis confirmed significant changes in the paired association and expression of traits with changing BAP concentration and type of olive cultivars. Likewise, the expression of all genes varied due to changes in BAP concentration in all cultivars, corresponding to variations in physiological and biochemical traits. Moreover, the spectrographs generated via scanning electron microscopy further indicated the variations in the distribution of elements in olive leaf samples due to varying BAP concentrations. Although all cultivars showed a significant response to in vitro varying concentrations of BAP, the response of Arbosana was statistically more significant. In conclusion, the current study proved the dynamic impact of the varying BAP concentrations on regulating the physiological, biochemical, and molecular attributes of olive cultivars.

Interplay of phytohormones and epigenetic regulation: A recipe for plant development and plasticity

Both phytohormone signaling and epigenetic mechanisms have long been known to play crucial roles in plant development and plasticity in response to ambient stimuli. Indeed, diverse signaling pathways mediated by phytohormones and epigenetic processes integrate multiple upstream signals to regulate various plant traits. Emerging evidence indicates that phytohormones and epigenetic processes interact at multiple levels. In this review, we summarize the current knowledge of the interplay between phytohormones and epigenetic processes from the perspective of phytohormone biology. We also review chemical regulators used in epigenetic studies and propose strategies for developing novel regulators using multidisciplinary approaches.

Light Deficiency Inhibits Growth by Affecting Photosynthesis Efficiency as well as JA and Ethylene Signaling in Endangered Plant Magnolia sinostellata

The endangered plant Magnolia sinostellata largely grows in the understory of forest and suffers light deficiency stress. It is generally recognized that the interaction between plant development and growth environment is intricate; however, the underlying molecular regulatory pathways by which light deficiency induced growth inhibition remain obscure. To understand the physiological and molecular mechanisms of plant response to shading caused light deficiency, we performed photosynthesis efficiency analysis and comparative transcriptome analysis in M. sinostellata leaves, which were subjected to shading treatments of different durations. Most of the parameters relevant to the photosynthesis systems were altered as the result of light deficiency treatment, which was also confirmed by the transcriptome analysis. Gene Ontology and KEGG pathway enrichment analyses illustrated that most of differential expression genes (DEGs) were enriched in photosynthesis-related pathways. Light deficiency may have accelerated leaf abscission by impacting the photosynthesis efficiency and hormone signaling. Further, shading could repress the expression of stress responsive transcription factors and R-genes, which confer disease resistance. This study provides valuable insight into light deficiency-induced molecular regulatory pathways in M. sinostellata and offers a theoretical basis for conservation and cultivation improvements of Magnolia and other endangered woody plants.