DataSheet_1_Salt stress in olive tree shapes resident endophytic microbiota.pdf

Olea europaea L. is a glycophyte representing one of the most important plants in the Mediterranean area, both from an economic and agricultural point of view. Its adaptability to different environmental conditions enables its cultivation in numerous agricultural scenarios, even on marginal areas, characterized by soils unsuitable for other crops. Salt stress represents one current major threats to crop production, including olive tree. In order to overcome this constraint, several cultivars have been evaluated over the years using biochemical and physiological methods to select the most suitable ones for cultivation in harsh environments. Thus the development of novel methodologies have provided useful tools for evaluating the adaptive capacity of cultivars, among which the evaluation of the plant-microbiota ratio, which is important for the maintenance of plant homeostasis. In the present study, four olive tree cultivars (two traditional and two for intensive cultivation) were subjected to saline stress using two concentrations of salt, 100 mM and 200 mM. The effects of stress on diverse cultivars were assessed by using biochemical analyses (i.e., proline, carotenoid and chlorophyll content), showing a cultivar-dependent response. Additionally, the olive tree response to stress was correlated with the leaf endophytic bacterial community. Results of the metabarcoding analyses showed a significant shift in the resident microbiome for plants subjected to moderate salt stress, which did not occur under extreme salt-stress conditions. In the whole, these results showed that the integration of stress markers and endophytic community represents a suitable approach to evaluate the adaptation of cultivars to environmental stresses.

油橄榄（Olea europaea L.）是一类甜土植物（glycophyte），从经济和农业维度来看，均为地中海地区极具价值的核心作物之一。其对多样环境条件具备良好适应性，可在诸多农业生产场景中推广种植，甚至可在其他作物难以存活的边际土地上栽培。盐胁迫是当前包括油橄榄在内的农作物生产面临的主要威胁之一。为应对这一制约瓶颈，多年来科研人员已通过生化与生理学方法对多个油橄榄品种开展评估，以筛选出可在恶劣环境下种植的优良品种。新型研究方法的发展为评估品种的适应能力提供了有效工具，其中植物-微生物群比例的评估对维持植物稳态至关重要。本研究选取4个油橄榄品种（2个传统品种与2个集约化栽培品种），分别施加100 mM与200 mM浓度的盐胁迫处理。通过生化分析（即脯氨酸、类胡萝卜素与叶绿素含量测定）评估盐胁迫对不同品种的影响，结果显示品种间的胁迫响应模式存在显著差异。此外，本研究还将油橄榄的胁迫响应与叶片内生细菌群落进行关联分析。宏条形码（metabarcoding）分析结果表明，经受中度盐胁迫的植株其原位微生物群落发生了显著偏移，而极端盐胁迫条件下未出现该变化。综上，本研究结果证实，将胁迫标志物与内生群落分析相结合，是评估品种对环境胁迫适应能力的可靠方法。