Fierro Camila, López-Cristoffanini Camilo, Meynard Andrés, Lovazzano Carlos, Castañeda Francisco, Guajardo Eduardo, Contreras-Porcia Loretto
Departamento de Ecología y Biodiversidad, Facultad de Ecología y Recursos Naturales, Universidad Andres Bello, República 440, Santiago, Chile.
Departamento de Biología Evolutiva, Ecología y Ciencias Ambientales, Facultad de Biología, Universidad de Barcelona, Diagonal 643, 08028, Barcelona, Spain.
Planta. 2017 Jun;245(6):1149-1164. doi: 10.1007/s00425-017-2673-0. Epub 2017 Mar 13.
The transcriptional modulation of desiccation tolerance factors in P. orbicularis explains its successful recuperation after water deficit. Differential responses to air exposure clarify seaweed distribution along intertidal rocky zones. Desiccation-tolerant seaweed species, such as Pyropia orbicularis, can tolerate near 96% water loss during air exposure. To understand the phenotypic plasticity of P. orbicularis to desiccation, several tolerance factors were assessed by RT-qPCR, Western-blot analysis, and enzymatic assays during the natural desiccation-rehydration cycle. Comparative enzymatic analyses were used to evidence differential responses between P. orbicularis and desiccation-sensitive species. The results showed that during desiccation, the relative mRNA levels of genes associated with basal metabolism [trehalose phosphate synthase (tps) and pyruvate dehydrogenase (pdh)] were overexpressed in P. orbicularis. Transcript levels related to antioxidant metabolism [peroxiredoxin (prx); thioredoxin (trx); catalase (cat); lipoxygenase (lox); ferredoxin (fnr); glutathione S-transferase (gst)], cellular detoxification [ABC transporter (abc) and ubiquitin (ubq)], and signal transduction [calmodulin (cam)] increased approximately 15- to 20-fold, with the majority returning to basal levels during the final hours of rehydration. In contrast, actin (act) and transcription factor 1 (tf1) transcripts were down-regulated. ABC transporter protein levels increased in P. orbicularis during desiccation, whereas PRX transcripts decreased. The antioxidant enzymes showed higher specific activity in P. orbicularis under desiccation, and sensitive species exhibited enzymatic inactivation and scarce ABC and PRX protein detection following prolonged desiccation. In conclusion, the reported findings contribute towards understanding the ecological distribution of intertidal seaweeds at the molecular and functional levels.
圆紫菜中耐干燥因子的转录调控解释了其在水分亏缺后成功恢复的原因。对空气暴露的不同反应阐明了潮间带岩石区域上海藻的分布情况。耐干燥的海藻物种，如圆紫菜，在空气暴露期间能够耐受近96%的水分流失。为了解圆紫菜对干燥的表型可塑性，在自然干燥-复水周期中，通过逆转录定量聚合酶链反应（RT-qPCR）、蛋白质免疫印迹分析和酶活性测定对几种耐受因子进行了评估。采用比较酶分析来证明圆紫菜与干燥敏感物种之间的不同反应。结果表明，在干燥过程中，与基础代谢相关的基因[海藻糖磷酸合酶（tps）和丙酮酸脱氢酶（pdh）]的相对mRNA水平在圆紫菜中过表达。与抗氧化代谢[过氧化物还原酶（prx）；硫氧还蛋白（trx）；过氧化氢酶（cat）；脂氧合酶（lox）；铁氧还蛋白（fnr）；谷胱甘肽S-转移酶（gst）]、细胞解毒[ABC转运蛋白（abc）和泛素（ubq）]以及信号转导[钙调蛋白（cam）]相关的转录水平增加了约15至20倍，大多数在复水的最后几小时恢复到基础水平。相比之下，肌动蛋白（act）和转录因子1（tf1）的转录本被下调。在干燥过程中，圆紫菜中ABC转运蛋白的水平增加，而PRX转录本减少。抗氧化酶在干燥条件下的圆紫菜中表现出更高的比活性，而敏感物种在长时间干燥后表现出酶失活，且几乎检测不到ABC和PRX蛋白。总之，所报道的研究结果有助于在分子和功能水平上理解潮间带海藻的生态分布。
