Plant Biotechnology Resource and Outreach Center, Department of Horticulture, Michigan State University, East Lansing, MI, 48824, USA.
BMC Plant Biol. 2018 May 31;18(1):98. doi: 10.1186/s12870-018-1311-8.
Blueberry cultivars require a fixed quantity of chilling hours during winter endo-dormancy for vernalization. In this study, transcriptome analysis using RNA sequencing data from nonchilled, chilled, and late pink buds of southern highbush blueberry 'Legacy' was performed to reveal genes associated with chilling accumulation and bud break.
Fully chilled 'Legacy' plants flowered normally whereas nonchilled plants could not flower. Compared to nonchilled flower buds, chilled flower buds showed differential expression of 89% of flowering pathway genes, 86% of MADS-box genes, and 84% of cold-regulated genes. Blueberry orthologues of FLOWERING LOCUS T (FT) did not show a differential expression in chilled flower buds (compared to nonchilled flower bud) but were up-regulated in late-pink buds (compared to chilled flower bud). Orthologoues of major MADS-box genes were significantly up-regulated in chilled flower buds and down-regulated in late-pink buds. Functional orthologues of FLOWERING LOCUS C (FLC) were not found in blueberry. Orthologues of Protein FD (FD), TERMINAL FLOWER 1 (TFL1), and LEAFY (LFY) were down-regulated in chilled flower buds and in late-pink buds compared to nonchilled flower bud.
The changes from nonchilled to chilled and chilled to late-pink buds are associated with transcriptional changes in a large number of differentially expressed (DE) phytohormone-related genes and DE flowering pathway genes. The profile of DE genes suggests that orthologues of FT, FD, TFL1, LFY, and MADS-box genes are the major genes involved in chilling-mediated blueberry bud-break. The results contribute to the comprehensive investigation of the vernalization-mediated flowering mechanism in woody plants.
蓝莓品种在冬季自然休眠期间需要一定数量的冷积才能春化。本研究利用 RNA 测序数据对南方高丛蓝莓‘遗产’未冷藏、冷藏和粉红后期花蕾进行转录组分析，揭示与冷积累和芽休眠相关的基因。
完全冷藏的‘遗产’植株正常开花，而未冷藏的植株不能开花。与未冷藏的花蕾相比，冷藏的花蕾中开花途径基因的表达差异为 89%，MADS 盒基因的表达差异为 86%，冷调控基因的表达差异为 84%。蓝莓与 FT（FLOWERING LOCUS T）同源物在冷藏花蕾（与未冷藏花蕾相比）中没有表现出差异表达，但在粉红后期花蕾（与冷藏花蕾相比）中上调。主要 MADS 盒基因的同源物在冷藏花蕾中显著上调，在粉红后期花蕾中下调。在蓝莓中未发现 FLC（FLOWERING LOCUS C）的功能同源物。FD（Protein FD）、TFL1（TERMINAL FLOWER 1）和 LFY（LEAFY）的功能同源物在冷藏花蕾和粉红后期花蕾中与未冷藏花蕾相比下调。
从未冷藏到冷藏，再从冷藏到粉红后期花蕾的变化与大量差异表达（DE）植物激素相关基因和 DE 开花途径基因的转录变化有关。DE 基因的特征表明，FT、FD、TFL1、LFY 和 MADS 盒基因的同源物是参与蓝莓芽休眠的主要基因。研究结果有助于对木本植物春化介导开花机制的综合研究。
