Expression values from 6 time points during the regeneration of secondary vascular System (SVS). Populus tomentosa

Secondary vascular system (SVS) development resulted from cambial growth is a currently not well understood process. Therefore, more studies are needed to shed more lights on the molecular mechanisms underpinning the cambial activity. The regeneration of SVS from debarked trunk that can mimic the vascular cambium-driven wood formation has developed and could be used to revealed a larger number of differentially expressed genes during the stages of cambium formation and xylem differentiation in Populus tomentosa. We used microarrays to detail the global programme of gene expression in 6 time points during the regeneration of SVS. Overall design: A 1-m strip of bark was peeled from 65 healthy P. tomentosa plants in a 4-year-old single clonal plantation (located in Tangshan, Hebei Province, China), starting 0.5 m from the tree base. Exposed tissue was wrapped with transparent plastic sheets to prevent desiccation. Samples were subsequently collected by scraping regenerating tissues from the whole surfaces of the trunks at the same daytime (between 10:00-11:00 am) at 7 days (D7), 10 days (D10), 12 days (D12), 16 days (D16), 18 days (D18), and 21 days (D21) after girdling (AG), and immediately frozen and stored in liquid nitrogen. Sampling was performed on three clonal trees at one time.

由形成层生长驱动的次生维管系统（secondary vascular system, SVS）发育过程，目前尚未得到充分解析。因此，亟需开展更多研究以阐明调控形成层活动的分子机制。目前已建立了从去树皮树干处再生SVS的实验体系，该体系可模拟由维管形成层驱动的木材形成过程，能够用于揭示毛白杨（Populus tomentosa）在形成层形成与木质部分化各阶段中的大量差异表达基因。为精细解析该再生过程的全基因组表达谱，本研究利用基因芯片（microarrays）对SVS再生过程中的6个时间点样本进行了分析。实验设计概况如下：从位于中国河北省唐山市的4年生毛白杨单无性系人工林中共选取65株健康植株，在距树干基部0.5米处剥离一条长1米的树皮条带；暴露的木质部组织用透明塑料薄膜包裹，以防止脱水。随后分别在环剥处理后（AG，after girdling）的第7天（D7）、第10天（D10）、第12天（D12）、第16天（D16）、第18天（D18）及第21天（D21），于每日上午10:00-11:00的同一时段刮取树干整个表面的再生组织作为样本；每个时间点的样本均取自3株无性系植株，采集后立即置于液氮中速冻并保存。