Transcriptome and targeted hormone metabolome reveal the molecular mechanisms of flower abscission in camellia

Abstract

IntroductionCamellia is among the most ornamentally valuable flowers and plants worldwide. Flower abscission typically causes significant financial losses by the horticultural landscape. Previous research has revealed that phytohormones, transcription factors, and other genes involved in floral development regulate the maintenance and mortality of flowersMethodsIn this study, for the first time, the transcriptomes and targeted hormone metabolomics of three developmental stages of the receptacles of two distinct camellia strains (CF: abscission strain, CHF: nonabscission strain) were analyzed to determine their roles in regulating blossom abscission in camellia.ResultsABA content was shown to be considerably upregulated throughout all phases of CF development, as were the genes implicated in the ABA production pathway and their downstream counterparts. Highly expressed genes in CF were involved in galactose metabolism, phenylpropanoid biosynthesis, amino and nucleotide sugar metabolism, pentose and glucuronate interconversions, and MAPK. Among others, highly expressed genes in CHF are associated with fructose and mannose metabolism, alpha-linolenic acid metabolism, biosynthesis of secondary metabolites, starch and sucrose metabolism, and cutin, suberin, and wax biosynthesis. A vast variety of stress response-related pathways and redox-related activities were also shown to be active in CHF. In contrast, CF dramatically activated pathways associated with lignin production, keratinogenesis, cell wall biogenesis, and ABA response. A comparative transcriptomic study of the CF and CHF pathways revealed that the downstream response pathways of hormones, including CTK, BR, IAA, ethylene, and GA, were very active in CF, indicating a significant amount of signal transduction and transcriptional regulation by CF. In addition, members of the transcription factor family, such as MYB, bHLH, MADS, and WD40, may regulate flower abscission.DiscussionA comparative transcriptome analysis of two distinct strains of camellia receptacles elucidates the molecular processes and regulatory characteristics of flower abscission and provides direction for the targeted improvement and breeding of camellia.

Comparative Transcriptome Analysis between Resistant and Susceptible Pakchoi Cultivars in Response to Downy Mildew

“…ETI is an accelerated and amplified PTI effect [6], and its occurrence leads to plant disease resistance. Long-term natural selection would produce novel pathogenic bacteria which can escape from ETI while also stimulating new resistance genes to restart ETI [7]. Following plant infection with pathogens, multiple defense genes encoding pathogenesis-related proteins (PRs) are activated in the infected and uninfected areas, leading to systemic acquired resistance (SAR) [8].…”

“…SA induces the formation of monomers of NPR1 from oligomers; SA-bound NPR1 enter into the nucleus to control the production of downstream resistance proteins, such as PRs induced by pathogens in infection [6]. Therefore, alteration of SA content and the expression of PRs involve the mechanism of plant disease resistance [7]. In this process, transcription factors, such as TGAs and WRKYs, interact with NPR1 to regulate the expression of downstream genes in the nucleus [8].…”