LSD1, EDS1 and PAD4 Conditionally Regulate Cellular Signaling Homeostasis, Photosynthesis, Water Use Efficiency and Seed Yield in Arabidopsis. Arabidopsis thaliana

There is growing evidence that for a comprehensive insight into the function of plant genes it is crucial to assess their functionalities under a wide range of conditions. In this study we examined the role of LESION SIMULATING DISEASE1 (LSD1), ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1) and PHYTOALEXIN DEFICIENT4 (PAD4) in the regulation of photosynthesis, water use efficiency (WUE), ROS/hormonal homeostasis and seed yield in Arabidopsis thaliana grown in the laboratory and in the field. We demonstrate that the LSD1 null mutant (lsd1), which is known to exhibit a runaway cell death in non-permissive conditions, proves to be more tolerant to combined drought and high-light stress than the wild type. Moreover, depending on growing conditions, it shows variations in WUE, salicylic acid and hydrogen peroxide concentrations, photosystem II maximum efficiency and in transcription profiles. However, despite these changes, lsd1 demonstrates similar seed yield under all tested conditions. All of these traits depend on EDS1 and PAD4. The differences in the pathways prevailing in the lsd1 in various growing environments are manifested by the significantly smaller number of transcripts deregulated in the field compared to the laboratory, with only 43 commonly regulated genes. Our data indicate that LSD1, EDS1 and PAD4 participate in the regulation of various molecular and physiological processes that influence Arabidopsis fitness. On the basis of these results we emphasize that the function of such important regulators as LSD1, EDS1 and PAD4 should be studied not only under stable laboratory conditions, but also in the environment abounding in multiple stresses. Overall design: Six genotypes x two conditions experiment including five-week-old WT (Ws), lsd1, pad4, eds1, eds1lsd1, and pad4lsd1 plants grown in laboratory or field conditions, hybridized in two loop-designs (lab and field). Two biological replicates. In total, 2 x 12 samples were hybridized on 24 Arabidopsis Gene Expression microarrays V4 (Agilent, two-color array) including color swap of replicate samples.

越来越多的研究证据表明，若要全面解析植物基因的功能，在广泛的环境条件下评估其功能至关重要。本研究以拟南芥（Arabidopsis thaliana）为材料，探究了LSD1（LESION SIMULATING DISEASE1）、EDS1（ENHANCED DISEASE SUSCEPTIBILITY1）与PAD4（PHYTOALEXIN DEFICIENT4）在实验室与田间种植条件下，对光合作用、水分利用效率（WUE）、活性氧（ROS）/激素稳态以及种子产量的调控作用。研究证实，已知在非许可条件下会出现失控性细胞死亡的LSD1功能缺失突变体（lsd1），相较于野生型，对干旱与高光协同胁迫的耐受性更强。此外，根据生长环境的差异，该突变体的水分利用效率、水杨酸与过氧化氢浓度、光系统II最大光合效率以及转录谱均会发生变化。尽管存在上述调控变化，lsd1在所有测试条件下的种子产量均与野生型保持相近水平。上述所有性状均依赖于EDS1与PAD4的存在。与实验室环境相比，田间环境下lsd1中失调的转录本数量显著更少，仅存在43个共同调控的基因，这体现了不同生长环境中lsd1所主导的通路差异。本研究数据表明，LSD1、EDS1与PAD4参与调控各类影响拟南芥生存适合度的分子与生理过程。基于上述结果，我们强调，诸如LSD1、EDS1与PAD4这类重要调控因子的功能，不应仅在稳定的实验室条件下开展研究，还应在存在多种胁迫的自然环境中进行探究。

整体实验设计：本实验采用6种基因型×2种环境条件的处理方案，供试材料为生长5周的野生型（Ws）、lsd1、pad4、eds1、eds1lsd1以及pad4lsd1植株，分别在实验室与田间环境下种植，并通过两套循环设计（实验室组与田间组）进行杂交。实验设置2次生物学重复，总计2×12个样本，均在24张拟南芥基因表达微阵列V4（Agilent，双色芯片）上完成杂交，其中包含重复样本的荧光互换对照。