Galicia-Campos Estrella, Velasco Ana García-Villaraco, Lucas Jose Antonio, Gutiérrez-Mañero F Javier, Ramos-Solano Beatriz
Faculty of Pharmacy, Universidad San Pablo-CEU Universities, 28668 Madrid, Spain.
Plants (Basel). 2024 Dec 20;13(24):3565. doi: 10.3390/plants13243565.
Plants are sessile organisms that overcome environmental stress by activating specific metabolic pathways, leading to adaptation and survival. In addition, they recruit beneficial bacterial strains to further improve their performance. As plant-growth-promoting rhizobacteria (PGPR) are able to trigger multiple targets to improve plant fitness, finding effective isolates for this purpose is of paramount importance. This metabolic activation involves the following two stages: the priming pre-challenge with no evident changes, and the post-challenge, which is characterized by a faster and more intense response. Eight strains, obtained in a previous study, were tested for their ability to improve plant growth, and to protect plants against biotic and abiotic stress. After the 16S rRNA gene sequencing, three isolates were selected for their ability to improve growth (G7), and to protect against biotic and abiotic stress (H47, mild protection, with a similar intensity for biotic and abiotic stress; L44, the highest protection to both); moreover the expression of Non-Expresser of Protein Resistance Gene 1 () and Protein resistance () as markers of the Salicylic Acid (SA) pathway, and lipooxygenase () and plant defensin gene () as markers of the Ethylene/Jasmonic Acid (Et/Ja) pathway, was determined 24 h after the stress challenge and compared to the expression in non-stressed plants. The results indicated that (i) the three strains prime according to the more marked and faster increases in gene expression upon stress challenge, (ii) all three strains activate the SA-mediated and the Et/Ja-mediated pathways, therefore conferring a wide protection against stress, and (iii) and , traditionally associated to Systemic Acquired Resistance (SAR) and Induced Systemic Resistance (ISR) protection against pathogenic stress, are also overexpressed under abiotic stress conditions. Therefore, it appears that the priming of the plant adaptive metabolism is strain-dependent, although each stress factor determines the intensity in the response of the expression of each gene; hence, the response is determined by the following three factors: the PGPR, the plant, and the stress factor.
植物是固着生物，通过激活特定的代谢途径来克服环境压力，从而实现适应和生存。此外，它们会招募有益细菌菌株以进一步提升自身性能。由于植物促生根际细菌（PGPR）能够触发多个靶点来提高植物适应性，因此寻找有效的此类分离株至关重要。这种代谢激活涉及以下两个阶段：预激发阶段，此时无明显变化；激发后阶段，其特征是反应更快且更强烈。对先前研究中获得的8株菌株进行了测试，以评估它们促进植物生长以及保护植物免受生物和非生物胁迫的能力。经过16S rRNA基因测序后，选择了三株分离株，其中一株（G7）具有促进生长的能力，另外两株（H47，轻度保护，对生物和非生物胁迫的保护强度相似；L44，对两者的保护作用最强）具有抵御生物和非生物胁迫的能力；此外，在胁迫处理24小时后，测定了作为水杨酸（SA）途径标志物的无抗性蛋白基因1（）和抗性蛋白（）的表达，以及作为乙烯/茉莉酸（Et/Ja）途径标志物的脂氧合酶（）和植物防御素基因（）的表达，并与未受胁迫植物中的表达进行了比较。结果表明：（i）这三株菌株通过胁迫处理后基因表达更显著且更快的增加来引发激发；（ii）所有三株菌株均激活了SA介导的途径和Et/Ja介导的途径，因此赋予了广泛的胁迫抗性；（iii）传统上与系统获得性抗性（SAR）和诱导系统抗性（ISR）对病原胁迫的保护相关的和，在非生物胁迫条件下也过表达。因此，可以看出植物适应性代谢的激发是菌株依赖性的，尽管每个胁迫因子决定了每个基因表达反应的强度；因此，反应由以下三个因素决定：PGPR、植物和胁迫因子。
