Department of Plant Breeding, Swedish University of Agricultural Sciences, Växtskyddsvägen 1, 23053, Alnarp, Sweden.
Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Artedigränd 7, 90187, Umeå, Sweden.
New Phytol. 2018 Jul;219(2):619-630. doi: 10.1111/nph.15197. Epub 2018 May 15.
The signalling pathways that control seasonal modulation of carbon metabolism in perennial plants are poorly understood. Using genetic, metabolic and natural variation approaches, we identify factors mediating photoperiodic control of storage lipid accumulation in the model tree hybrid aspen (Populus tremula × tremuloides). We characterized lipid accumulation in transgenic hybrid aspen with impaired photoperiodic and hormonal responses. Genome-wide association mapping was performed in Swedish aspen (P. tremula) genotypes to determine genetic loci associated with genotype variation in lipid content. Our data show that the storage lipid triacylglycerol (TAG) accumulates in cambial meristem and pith rays of aspen in response to photoperiodic signal controlling growth cessation and dormancy induction. We show that photoperiodic control of TAG accumulation is mediated by the FLOWERING LOCUS T/CONSTANS module, which also controls the induction of growth cessation. Hormonal and chromatin remodelling pathways also contribute to TAG accumulation by photoperiodic signal. Natural variation exists in lipid accumulation that is controlled by input from multiple loci. Our data shed light on how the control of storage metabolism is temporally coordinated with growth cessation and dormancy by photoperiodic signal, and reveals that storage lipid accumulation between seeds and perennating organs of trees may involve distinct regulatory circuits.
控制多年生植物碳代谢季节性调节的信号通路知之甚少。本研究采用遗传、代谢和自然变异方法，鉴定了介导模式树种杂种欧洲山杨（Populus tremula × tremuloides）光周期控制储存脂质积累的因素。本研究通过对光周期和激素反应受损的杂种欧洲山杨转基因植株进行了特征描述，确定了与脂质含量基因型变异相关的遗传位点。我们的数据表明，在响应控制生长停止和休眠诱导的光周期信号时，储存脂质三酰基甘油(TAG)在形成层分生组织和韧皮射线中积累。研究表明，TAG 积累的光周期调控是由开花时间/持续时间（FLOWERING LOCUS T/CONSTANS，FT/CO）模块介导的，该模块还控制生长停止的诱导。激素和染色质重塑途径也通过光周期信号促进 TAG 积累。脂质积累存在自然变异，受多个基因座的输入控制。本研究阐明了储存代谢的控制如何通过光周期信号与生长停止和休眠进行时间协调，并揭示了种子和树木多年生器官之间的储存脂质积累可能涉及不同的调控回路。
