Abstract
BackgroundGrape is highly sensitive to gibberellin (GA), which is crucial during seed and berry development (SBD) either by itself or by interacting with other hormones, such as auxin, Abscisic acid (ABA), and Cytokinin (CK). However, no systematic analysis of GA metabolic and signal transduction (MST) pathway has been undertaken in grapevine.ResultsIn this study, total endogenous GA3 content significantly decreased during SBD, and a total of 48 known genes in GA metabolic (GAM; 31) and signal transduction (ST; 17) pathways were identified in this process. In the GAM pathway, out of 31 genes, VvGA20ox1–1, VvGA3ox4–1, and VvGA2ox1–1 may be the major factors interacting at the green-berry stage (GBS) accompanied with higher accumulation rate. GA biosynthesis was greater than GA inactivation at GBS, confirming the importance of seeds in GA synthesis. The visible correlation between endogenous GA3 content and gene expression profiles suggested that the transcriptional regulation of GA biosynthesis pathway genes was a key mechanism of GA accumulation at the stone-hardening stage (SHS). Interestingly, we observed a negative feedback regulation between VvGA3oxs-VvGAI1–4, VvGA2oxs-VvGAI1–4, and VvGID1B-VvGAI1–4 in maintaining the balance of GA3 content in berries. Moreover, 11 miRNAs may be involved in the modulation of GA MST pathway by mediating their target genes, such as VvGA3ox, VvGID1B, and VvGAMYB. Many genes in auxin, ABA, and CK MST pathways were further identified and found to have a special pattern in the berry, and the crosstalk between GA and these hormones may modulate the complex process during SBD through the interaction gene network of the multihormone pathway. Lastly, based on the expression characterization of multihormone MST pathway genes, a proposed model of the GA-mediated multihormone regulatory network during SBD was proposed.ConclusionsOur results provided novel insights into GA-mediated regulatory networks during SBD in grape. The complexity of GA-mediated multihormone ST in SBD was also elucidated, thereby providing valuable information for future functional characterizations of specific genes in grape.
Highlights
Grape is highly sensitive to gibberellin (GA), which is crucial during seed and berry development (SBD) either by itself or by interacting with other hormones, such as auxin, Abscisic acid (ABA), and Cytokinin (CK)
Grape is highly sensitive to gibberellin (GA), which is one of the essentially significant hormones during SBD
The developmental curve and average weight of berries and seed showed a rapid increase from green-berry stage (GBS) to stone-hardening stage (SHS), whereas they maintained stability during berry-veraison stage (BVS) and berry-ripening stage (BRS) (Fig. 1b and c)
Summary
Plant material Three-year-old ‘Fujiminori’ grape trees grown in Nanjing, China (N32°02′12.77′′, E118°37′33.25′′) were chosen as the experimental material. The plant materials were grown under common field conditions at the Jiangsu Vocational College of Agriculture and Forestry grape farm, Jurong, China (our long-term partners). A total of 12 samples, comprising four stages berry, and including three biological replicates, were sequenced. RNA for Illumina sequencing was purified from 40 uniform and averagesized berries with seeds sampled from 20 clusters to study a representative biological selection of transcripts at each stage. Total RNA extraction, construction of cDNA library, and Illumina deep sequencing Total RNA of different stages (i.e., GBS, SHS, BVS, and BRS) berry samples was extracted using TRIzol reagent (Invitrogen, Carlsbad, CA, USA). The transcriptome were sequenced using Illumina HiSeqTM 2500 Shanghai Hanyu Biotechnology Company (Shanghai, China) [68]
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