The Role of H3K27me3 in Eggplant’s Early Defense Against Frankliniella occidentalis
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript is well written, straight forward and I enjoyed reading it. I have only some minor suggestions.
Comments for author File: 
Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe article, “Ch-IP and RNA-seq showed histone H3 lysine 27 trimethylation in eggplants’ early defense against Fankliniella occidentalis”, by Zheng et al., is well written, thoughtful and scientifically sound. Though this study is not particularly unique (doi.org/10.1016/j.molp.2022.06.003; doi.org/10.1111/mpp.13446) it adds to an increasing wealth of knowledge of hierarchical gene regulation and control involved in plant defenses induced by stress, including pest herbivory. With this said, this article should meet the criteria of the Horticulturae Journal.
By using ChIP-seq analysis to compare the epigenetic backgrounds of healthy eggplants to those exposed to western flower thrips (WFT; F. occidentalis), Zheng et al., demonstrate that the H3K27me3 histone landscape is altered significantly upon WFT exposure, with H3K27me3 peaks that are both downregulated and upregulated. Notably, many of the downregulated peaks (an indicator of gene activation) are proximal to genes associated with early plant defense pathways. For example, KEGG analysis of the ChIP sequences includes genes associated with terpenoid biosynthesis, flavonoid biosynthesis and phenylpropanoid biosynthesis. Whereas with GO annotation, the upregulated peaks were aligned with DNA conformation change and response to lipids, for example.
To expand upon the ChIP-results, RNA-seq analysis of WFT exposed vs unexposed eggplants was carried out. These results emphasized a reprogramming of gene transcription that also trended towards plant defense. Furthermore, by merging the ChIP-seq and RNA-seq data, 21 overlapping genes were highlighted between techniques. From these, six genes were selected for enhanced transcription and reduced H3K27me3 induced by WFT herbivory. All were further analyzed using qPCR that compared mRNA from an expanded panel of WFT exposed vs unexposed eggplants. These genes (SmSLAH1, SmMJE10, SmPUB23, SmMAPKKK18, SmPLA1 and SmCML38), which all showed significant upregulation in WFT exposed plants, in one form or another, are involved with abscisic acid (ABA) and jasmonic acid (JA) synthesis and signaling pathways. These being strongly linked to early plant defense.
So overall, this study nicely demonstrates how insect herbivory induces hierarchical epigenetic changes associated with the regulation of H3K27me3 that subsequently influence the transcriptome by gearing it towards early plant defenses.
Additional minor comments are included in the PDF uploaded.
Comments for author File: Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
