Biosciences Research Laboratory, USDA-ARS, 1605 Albrecht Blvd. N, Fargo, ND, 58102-2765, USA.
Plant Mol Biol. 2014 Nov;86(4-5):409-24. doi: 10.1007/s11103-014-0237-2. Epub 2014 Aug 24.
Vegetative shoot growth from underground adventitious buds of leafy spurge is critical for survival of this invasive perennial weed after episodes of severe abiotic stress. To determine the impact that dehydration-stress has on molecular mechanisms associated with vegetative reproduction of leafy spurge, greenhouse plants were exposed to mild- (3-day), intermediate- (7-day), severe- (14-day) and extended- (21-day) dehydration treatments. Aerial tissues of treated plants were then decapitated and soil was rehydrated to determine the growth potential of underground adventitious buds. Compared to well-watered plants, mild-dehydration accelerated new vegetative shoot growth, whereas intermediate- through extended-dehydration treatments both delayed and reduced shoot growth. Results of vegetative regrowth further confirmed that 14 days of dehydration induced a full-state of endodormancy in crown buds, which was correlated with a significant (P < 0.05) change in abundance of 2,124 transcripts. Sub-network enrichment analyses of transcriptome data obtained from the various levels of dehydration treatment also identified central hubs of over-represented genes involved in processes such as hormone signaling (i.e., ABA, auxin, ethylene, GA, and JA), response to abiotic stress (DREB1A/2A, RD22) and light (PIF3), phosphorylation (MPK4/6), circadian regulation (CRY2, PHYA), and flowering (AGL20, AP2, FLC). Further, results from this and previous studies highlight homologs most similar to Arabidopsis HY5, MAF3, RVE1 and RD22 as potential molecular markers for endodormancy in crown buds of leafy spurge. Early response to mild dehydration also highlighted involvement of upstream ethylene and JA-signaling, whereas severe dehydration impacted ABA-signaling. The identification of conserved ABRE- and MYC-consensus, cis-acting elements in the promoter of leafy spurge genomic clones similar to Arabidopsis RVE1 (AT5G17300) implicates a potential role for ABA-signaling in its dehydration-induced expression. Response of these molecular mechanisms to dehydration-stress provides insights on the ability of invasive perennial weeds to adapt and survive under harsh environments, which will be beneficial for addressing future management practices.
地下不定芽的营养体生长对这种入侵性多年生杂草在经历严重非生物胁迫后生存至关重要。为了确定干旱胁迫对与白屈菜属植物营养繁殖相关的分子机制的影响，温室植物被暴露于轻度（3 天）、中度（7 天）、重度（14 天）和延长（21 天）干旱处理中。然后，将处理过的植物的地上组织斩首，给土壤浇水以确定地下不定芽的生长潜力。与水分充足的植物相比，轻度干旱加速了新的营养体生长，而中度至延长干旱处理既延迟了又减少了芽的生长。营养体再生的结果进一步证实，14 天的干旱诱导了冠芽的完全休眠状态，这与丰度发生显著（P < 0.05）变化的 2124 个转录本相关。对来自各种干旱处理水平的转录组数据进行的子网络富集分析还鉴定了涉及激素信号（如 ABA、生长素、乙烯、GA 和 JA）、非生物胁迫响应（DREB1A/2A、RD22）和光（PIF3）、磷酸化（MPK4/6）、昼夜节律调节（CRY2、PHYA）和开花（AGL20、AP2、FLC）等过程的过度表达基因的中心枢纽。此外，本研究和以前的研究结果突出了与拟南芥 HY5、MAF3、RVE1 和 RD22 最相似的同源物作为白屈菜属植物冠芽休眠的潜在分子标记。对轻度干旱的早期响应也强调了上游乙烯和 JA 信号的参与，而严重干旱则影响了 ABA 信号。在白屈菜属基因组克隆的启动子中发现了与拟南芥 RVE1（AT5G17300）相似的保守 ABRE 和 MYC 一致的顺式作用元件，表明 ABA 信号在其脱水诱导表达中可能发挥作用。这些分子机制对干旱胁迫的响应提供了有关入侵性多年生杂草在恶劣环境下适应和生存能力的见解，这将有助于解决未来的管理实践。
