Transcriptome analysis reveals the effect of grafting on gossypol biosynthesis and gland formation in cotton

Abstract

Background Gossypol is a unique secondary metabolite and sesquiterpene in cotton, which is mainly synthesized in the root system of cotton and exhibits many biological activities. Previous research found that grafting affected the density of pigment glands and the gossypol content in cotton. Results This study performed a transcriptome analysis on cotton rootstocks and scions of four grafting methods. The gene expression of mutual grafting and self-grafting was compared to explore the potential genes involved in gossypol biosynthesis. A total of six differentially expressed enzymes were found in the main pathway of gossypol synthesis-sesquiterpene and triterpene biosynthesis (map00909): lupeol synthase (LUP1, EC:5.4.99.41), beta-amyrin synthase (LUP2, EC:5.4.99.39), squalene monooxygenase (SQLE, EC:1.14.14.17), squalene synthase (FDFT1, EC:2.5.1.21), (-)-germacrene D synthase (GERD, EC:4.2.3.75), ( +)-delta-cadinene synthase (CADS, EC:4.2.3.13). By comparing the results of the gossypol content and the density of the pigment gland, we speculated that these six enzymes might affect the biosynthesis of gossypol. It was verified by qRT-PCR analysis that grafting could influence gene expression of scion and stock. After suppressing the expression of the LUP1, FDFT1, and CAD genes by VIGS technology, the gossypol content in plants was significantly down-regulated. Conclusions These results indicate the potential molecular mechanism of gossypol synthesis during the grafting process and provide a theoretical foundation for further research on gossypol biosynthesis.

Utilization of Secondary Metabolites in Cotton Production

“…The glands of cottonseeds contain mostly gossypol with traces of deoxyhemigossypol, and the glands of cotton leaves contain hemigossypolone, a gossypol derivative, and heliocides [70]. On fresh weight basis, cotton seed (cotyledons) usually has similar gossypol content of around 1% in roots at the harvesting stage (Yue, unpublished data); on dry weight basis, cotton root usually has the highest gossypol content [66] among different plant parts, which is consistent with the recent progresses that cotyledon (seeds) and roots are the source of gossypol for the whole plants [61,71]. Structures of some common terpenoids in cotton plants.…”

Comparative physiological, biochemical, metabolomic, and transcriptomic analyses reveal the formation mechanism of heartwood for Acacia melanoxylon

“…Geranylgeranyl diphosphate (GGPP) produced by GGDS serves as a precursor for many diphosphates, including farnesyl-PP, Geranylgeranyl-PP, and Geranyl-PP [ 52 , 53 ]. Farnesyl-diphosphate (FPS) reduced farnesyl-PP to squalene, and then squalene monooxygenase (SME) oxidized squalene to (s)-squalene-2, 3-epoxide in sesquiterpenoid and triterpenoid biosynthesis [ 54 , 55 ]. Up-regulation of FPS and SME transcripts may indicate a relatively high accumulation of F-PP and squalene for sesquiterpenes and monoterpenes in HW.…”

Functional Characterization of Candidate Genes, Gohir.D05G103700 and Gohir.D12G153600, Identified through Expression QTL Analysis Using Virus-Induced Gene Silencing in Upland Cotton (Gossypium hirsutum L.)

“…The following PCR profile was used for the gene expression analysis: initial denaturation at 95 • C for 3 min followed by 50 cycles at 95 • C for 10 s and 56 • C (Gohir.D05G103700 and ACTIN1) or 59.5 • C (Gohir.D12G153600) for 30 s and 50 cycles of melt curve analysis at 56 • C to 93.5 • C for 10 s and final incubation at 4 • C. The cotton ACTIN1 gene was used as an internal control for data normalization. The gene expression data were analyzed using the 2 −∆∆Ct method and presented as log 2 of the fold change relative to the reference gene [40].…”