Song Guo-Qing, Gao Xuan
Plant Biotechnology Resource and Outreach Center, Department of Horticulture, Michigan State University, East Lansing, MI, 48824, USA.
Key Laboratory for the Conservation and Utilization of Important Biological Resources, College of Life Sciences, Anhui Normal University, Wuhu, 241000, China.
BMC Plant Biol. 2017 Jun 19;17(1):106. doi: 10.1186/s12870-017-1053-z.
Constitutive expression of the CBF/DREB1 for increasing freezing tolerance in woody plants is often associated with other phenotypic changes including dwarf plant and delayed flowering. These phenotypic changes have been observed when Arabidopsis DWARF AND DELAYED FLOWERING 1 (DDF1) was overexpressed in A. thaliana plants. To date, the DDF1 orthologues have not been studied in woody plants. The aim of this study is to investigate transcriptomic responses to the overexpression of blueberry (Vaccinium corymbosum) DDF1 (herein, VcDDF1-OX).
The VcDDF1-OX resulted in enhanced freezing tolerance in tetraploid blueberry plants and did not result in significant changes in plant size, chilling requirement, and flowering time. Comparative transcriptome analysis of transgenic 'Legacy-VcDDF1-OX' plants containing an overexpressed VcDDF1 with non-transgenic highbush blueberry 'Legacy' plants revealed the VcDDF1-OX derived differentially expressed (DE) genes and transcripts in the pathways of cold-response, plant flowering, DELLA proteins, and plant phytohormones. The increase in freezing tolerance was associated to the expression of cold-regulated genes (CORs) and the ethylene pathway genes. The unchanged plant size, dormancy and flowering were due to the minimal effect of the VcDDF1-OX on the expression of DELLA proteins, flowering pathway genes, and the other phytohormone genes related to plant growth and development. The DE genes in auxin and cytokinin pathways suggest that the VcDDF1-OX has also altered plant tolerance to drought and high salinity.
A DDF1 orthologue in blueberry functioned differently from the DDF1 reported in Arabidopsis. The overexpression of VcDDF1 or its orthologues is a new approach to increase freezing tolerance of deciduous woody plant species with no obvious effect on plant size and plant flowering time.
组成型表达CBF/DREB1以提高木本植物的抗冻性，通常与其他表型变化相关，包括植株矮小和开花延迟。当拟南芥矮化与开花延迟1（DDF1）在拟南芥植株中过表达时，已观察到这些表型变化。迄今为止，尚未在木本植物中研究DDF1直系同源基因。本研究的目的是调查蓝莓（Vaccinium corymbosum）DDF1（以下简称VcDDF1 - OX）过表达的转录组反应。
VcDDF1 - OX使四倍体蓝莓植株的抗冻性增强，且未导致植株大小、需冷量和开花时间发生显著变化。对含有过表达VcDDF1的转基因‘遗产 - VcDDF1 - OX’植株与非转基因高丛蓝莓‘遗产’植株进行比较转录组分析，揭示了VcDDF1 - OX在冷响应、植物开花、DELLA蛋白和植物激素途径中产生差异表达（DE）基因和转录本。抗冻性的提高与冷调节基因（CORs）和乙烯途径基因的表达有关。植株大小、休眠和开花未改变是由于VcDDF1 - OX对DELLA蛋白、开花途径基因以及与植物生长发育相关的其他植物激素基因的表达影响最小。生长素和细胞分裂素途径中的DE基因表明，VcDDF1 - OX也改变了植物对干旱和高盐度的耐受性。
蓝莓中的DDF1直系同源基因的功能与拟南芥中报道的DDF1不同。过表达VcDDF1或其直系同源基因是提高落叶木本植物抗冻性的一种新方法，对植株大小和开花时间无明显影响。
