WITHDRAWN: De novo assembly and comparative transcriptome analysis revealed the genes that were potentially involved in defensive terpenoids emission in the wheat against the wheat aphid Sitobion avenae (Fabricius)

Abstract

Background Terpenoid volatiles play an important role directly or indirectly in the plant defense mechanisms against herbivores, including the gramineous crops such as transgenic rice and corn. The conventional varieties of wheat are important gramineous cereal crops that lack aphid-resistant genes. Therefore, it is necessary to seek the aphid-resistant genes by screening for potential terpenoid synthase genes in the wheat germplasm resources. Results The result showed that aphid-damaged Octoploid Tirtitrigia emitted a higher amount of S-linalool, ent-kaurene, (+)-delta-cadinene, (3S,6E)-nerolidol as compared to the intact plant. In addition, (E)-β-caryophyllene, β‐Myrcene, (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) were new volatile terpenoids emitted by the damaged plant. Further olfactory responses tests showed that S-linalool significantly repelled Sitobion avenae (Fabricius). After de novo assembly and quantitative assessment, a total of 182348 (74.8%) unigenes were annotated by alignment with the public protein databases. Of these unigenes, 2389 differentially expressed genes were identified between the intact and damaged ears of Octoploid Trititrigia. The expression profile of 10 randomly selected TPSs was confirmed with RT-qPCR. Candidate genes involved in terpenes biosynthesis were identified by showing the significant transcript changes between the intact and damaged plant ears of Octoploid Trititrigia. The transcript abundances of terpenes biosynthetic pathway-related genes were also positively correlated with the production of volatile terpenoids in the ears. The unigenes of S-linalool synthase gene was mapped to the cloned cDNA WT008_M07 (AK333728) and WT013_P07 (AK335856) of the Chinese spring wheat cultivar. The predicted protein complete ORF sequence (TaLIS1/2) when compared with the S-linalool synthase gene of other species, contained an aspartate-rich region DDxxD motif. Its function was characterized as coordinating the divalent metal ions involved in substrate binding. Furthermore, the phylogenetic tree results indicated that the TaLIS1 and TuNES1 are highly homologous. Conclusions This assembled transcriptome of S. avenae-damaged Octoploid Trititrigia and the intact ears could provide more molecular resources for the future functional characterization analysis of genomics in volatile terpenoids involved in direct or indirect defenses. Our study describes the metabolic regulation mechanism of the volatile terpenoids in the gramineous crops, which provides support for both breeding and genetic modification of the wheat varieties resistant to wheat aphid.

Terpene Synthase Gene OtLIS Confers Wheat Resistance to Sitobion avenae by Regulating Linalool Emission

“…29,55,56 Then, we used transcriptomic data of the intact and aphiddamaged octoploid Trititrigia heads to screen the regulatory genes in the terpene biosynthetic pathway. 47 This assembled transcriptome could be used as a database of the wheat S2.…”

“…29,55,56 Then, we used transcriptomic data of the intact and aphiddamaged octoploid Trititrigia heads to screen the regulatory genes in the terpene biosynthetic pathway. 47 This assembled transcriptome could be used as a database of the wheat germplasm to search for high-quality aphid-resistant genes and provide more molecular resources for future functional characterization analysis of aphid resistance. The emission of the volatile terpenoid S-linalool was higher in aphid-fed octoploid Trititrigia heads than untreated heads.…”

“…Some TPS s have been identified, and even successfully used to increase direct plant defense , or indirect plant defense by attracting natural enemies of the herbivores. − A few TPS s have been discovered in the field crops, ,, which have greatly promoted the understanding of the mediation of terpene compound biosynthesis. Meanwhile, studies have reported that the expression levels of TPSs were significantly correlated with pest-defense mechanisms in the plants. ,, Then, we used transcriptomic data of the intact and aphid-damaged octoploid Trititrigia heads to screen the regulatory genes in the terpene biosynthetic pathway . This assembled transcriptome could be used as a database of the wheat germplasm to search for high-quality aphid-resistant genes and provide more molecular resources for future functional characterization analysis of aphid resistance.…”

“…Transcriptome analysis was performed both on intact and aphid-infected wheat heads. 47 Total RNA was extracted from three biological replicates of the flowering head using a Trizol reagent (Invitrogen) according to the manufacturer's instructions and then treated with RNase-free DNase I (Invitrogen). Each biological replicate contained a single flowering head.…”