Table_2_Characterization of Biostimulant Mode of Action Using Novel Multi-Trait High-Throughput Screening of Arabidopsis Germination and Rosette Growth.XLSX

Environmental stresses have a significant effect on agricultural crop productivity worldwide. Exposure of seeds to abiotic stresses, such as salinity among others, results in lower seed viability, reduced germination, and poor seedling establishment. Alternative agronomic practices, e.g., the use of plant biostimulants, have attracted considerable interest from the scientific community and commercial enterprises. Biostimulants, i.e., products of biological origin (including bacteria, fungi, seaweeds, higher plants, or animals) have significant potential for (i) improving physiological processes in plants and (ii) stimulating germination, growth and stress tolerance. However, biostimulants are diverse, and can range from single compounds to complex matrices with different groups of bioactive components that have only been partly characterized. Due to the complex mixtures of biologically active compounds present in biostimulants, efficient methods for characterizing their potential mode of action are needed. In this study, we report the development of a novel complex approach to biological activity testing, based on multi-trait high-throughput screening (MTHTS) of Arabidopsis characteristics. These include the in vitro germination rate, early seedling establishment capacity, growth capacity under stress and stress response. The method is suitable for identifying new biostimulants and characterizing their mode of action. Representatives of compatible solutes such as amino acids and polyamines known to be present in many of the biostimulant irrespective of their origin, i.e., well-established biostimulants that enhance stress tolerance and crop productivity, were used for the assay optimization and validation. The selected compounds were applied through seed priming over a broad concentration range and the effect was investigated simultaneously under control, moderate stress and severe salt stress conditions. The new MTHTS approach represents a powerful tool in the field of biostimulant research and development and offers direct classification of the biostimulants mode of action into three categories: (1) plant growth promotors/inhibitors, (2) stress alleviators, and (3) combined action.

环境胁迫对全球农作物生产力具有显著影响。种子经受盐胁迫等非生物胁迫时，会出现种子活力下降、发芽率降低及幼苗建植不良的问题。替代农艺措施（例如施用植物生物刺激素（plant biostimulants））已受到科学界与商业企业的广泛关注。生物刺激素指源自生物的制品（涵盖细菌、真菌、海藻、高等植物或动物来源），具备两大重要应用潜力：一是改善植物生理过程，二是促进发芽、生长并提升抗逆性。然而生物刺激素种类繁多，可从单一化合物到包含多组仅部分完成表征的生物活性成分的复杂基质不等。鉴于生物刺激素中含有复杂的生物活性化合物混合物，亟需开发可有效表征其潜在作用模式的方法。本研究开发了一种基于拟南芥（Arabidopsis）性状的多性状高通量筛选（multi-trait high-throughput screening, MTHTS）新型复合生物活性检测方法，该方法涵盖体外发芽率、早期幼苗建植能力、胁迫下生长能力以及胁迫响应等检测指标，可用于筛选新型生物刺激素并表征其作用模式。选取氨基酸、多胺等相容性溶质（compatible solutes）类代表物质开展试验优化与验证——这类物质广泛存在于各类来源的生物刺激素中，是公认可提升抗逆性与作物生产力的成熟生物刺激素。通过宽浓度梯度的种子引发（seed priming）方式施加所选化合物，并同时在对照、中度胁迫与重度盐胁迫条件下探究其作用效果。这种新型MTHTS方法是生物刺激素研发领域的强有力工具，可将生物刺激素的作用模式直接划分为三大类别：1. 植物生长促进/抑制剂；2. 胁迫缓解剂；3. 兼具双重作用的复合类型。