Transcriptomics and Antioxidant Analysis of Two Chinese Chestnut (Castanea mollissima BL.) Varieties Provides New Insights Into the Mechanisms of Resistance to Gall Wasp Dryocosmus kuriphilus Infestation

Abstract

Chinese chestnut is a popular fruit tree with a high nutritional value of its nuts, which can suffer from infestation by the chestnut gall wasp Dryocosmus kuriphilus (GWDK) that results in gall formation and resultant loss of production and profitability. The physiological and molecular mechanisms of GWDK resistance found in certain genotypes currently remains elusive. To gain new insights into this phenomenon, a series of RNA-Seq integrated with metabolomic profiling experiments were executed to investigate the chemical and transcriptional differences in response to GWDK infestation in two contrasting chestnut varieties grown in China (the susceptible “HongLi,” HL and the partially resistant “Shuhe_Wuyingli,” SW). Three time points were selected for comparison: The initiation stage (A), growth stage (B), and maturation stage (C). Results showed that concentrations of hydrogen peroxide (H2O2) and the activities of peroxidase (POD) and superoxide dismutase (SOD) enzyme were elevated in the resistant SW leaves compared with those in HL leaves at all three developmental stages, while catalase (CAT) and polyphenol oxidase (PPO) activities were mostly higher in HL leaves. RNA-Seq transcriptomic analyses of HL and SW leaves revealed that various metabolic pathways involved in GWDK stress responses, such as plant hormone signal transduction, MAPK signaling, and the peroxisome pathway, were enriched in the contrasting samples. Moreover, the weighted gene co-expression network analysis (WGCNA) of differentially expressed genes in the POD pathway combined with transcription factors (TFs) indicated that the expression of TF members of bHLH, WRKY, NAC, and MYB family positively correlated with POD pathway gene expression. The TFs CmbHLH130 (EVM0032437), CmWRKY31 (EVM0017000), CmNAC50 (EVM0000033), and CmPHL12 (EVM0007330) were identified as putative TFs that participate in the regulation of insect-induced plant enzyme activities in chestnut, which may contribute to GWDK resistance in SW. Expression levels of 8 random differentially expressed genes (DEGs) were furthermore selected to perform quantitative reverse transcription PCR (qRT-PCR) to validate the accuracy of the RNA-Seq-derived expression patterns. This study guides the functional analyses of further candidate genes and mechanisms important for GWDK resistance in chestnuts in the future as well as can help in identifying the master transcriptional regulators and important enzyme steps that support major insect defense pathways in chestnut.

Different responses of two maize cultivars to Spodoptera frugiperda (Lepidoptera: Noctuidae) larvae infestation provide insights into their differences in resistance

“…After gall wasp Dryocosmus kuriphilus (GWDK) infestation, at all three stages of development, the activities of the POD and SOD enzymes were higher in the resistant chestnut variety leaves than they were in the susceptible chestnut variety leaves. On the other hand, the activities of the CAT and PPO enzymes were mostly higher in the susceptible chestnut variety leaves (Zhu C. et al, 2022). In present study, both the S. frugiperda-infested and the control leaves, from 0 h onwards, the activities of SOD, POD, and CAT in ZD958 were significantly higher than that in JG218 at the same point of time, except for CAT at 6 h in the S. frugiperda-infested leaves, which is compatible with the above mentioned that the activities of antioxidant enzymes are higher in resistant ones.…”

Transcriptomic Analysis to Unravel Potential Pathways and Genes Involved in Pecan (Carya illinoinensis) Resistance to Pestalotiopsis microspora

“…Nine DEGs annotated as TIFY, WRKY TFs, and PRGs were selected from RNA-Seq data and analyzed by qRT-PCR to validate the expression patterns, as described previously [ 57 ]. Specific primers ( Table S8 ) for qRT-PCR were designed with Primer Premier 5 software (Palo Alto, San Francisco, CA, USA).…”

Terpene Synthase Gene Family in Chinese Chestnut (Castanea mollissima BL.) Harbors Two Sesquiterpene Synthase Genes Implicated in Defense against Gall Wasp Dryocosmus kuriphilus

“…Fragments per kilobase of exon model per million reads mapped (FPKM) values of RNA-seq data were used to determine the relative gene expressions. The expression patterns of CmTPSs in leaves, cane, flowers (inflorescences), buds, and roots were determined using RNA-seq data published by Wang et al 20 The expressions of CmTPSs in "HY", "HN", and "SN" samples were inferred from previously published data (NCBI SRA accession PRJNA791965 18 ).…”

“…During the vegetative growth and development of chestnut, plants are easily infested by the gall wasp Dryocosmus kuriphilus (Hymenoptera: Cynipidae, GWDK). GWDK is one of the main pests of Chinese chestnut and can produce large galls upon infested plant leaves or buds, affecting the growth and photosynthesis of plants and eventually leading to the loss of nut productions and economic values . To counter herbivory attacks, plants have developed an efficient and versatile defense system to recognize signals from herbivores, ultimately leading to the induction of the biosynthesis of direct defense compounds such as terpenoids that can act against a broad spectrum of pests.…”

“…GWDK is one of the main pests of Chinese chestnut and can produce large galls upon infested plant leaves or buds, affecting the growth and photosynthesis of plants and eventually leading to the loss of nut productions and economic values. 18 To counter herbivory attacks, plants have developed an efficient and versatile defense system to recognize signals from herbivores, ultimately leading to the induction of the biosynthesis of direct defense compounds such as terpenoids that can act against a broad spectrum of pests. It is important to gain more insight into the relationship between terpene compounds and GWDK herbivore defense in chestnut buds and leaves.…”