Departament de Ciències Agràries i del Medi Natural, Universitat Jaume I, Avda. Sos Baynat s/n, 12071, Castellón de la Plana, Spain.
Environmental Protection Department, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Profesor Albareda 1, 18008, Granada, Spain.
J Plant Physiol. 2018 Sep;228:208-217. doi: 10.1016/j.jplph.2018.06.003. Epub 2018 Jun 10.
Plants are constantly releasing root exudates to the rhizosphere. These compounds are responsible for different (positive or negative) interactions with other organisms, including plants, fungi or bacteria. In this work, the effect of root exudates obtained from in vitro cultured citrus plants on two rhizobacteria (Pseudomonas putida KT2440 and Novosphingobium sp. HR1a) was evaluated. Root exudates were obtained from two citrus genotypes differing in their sensitivity to salt and heat stress and differentially affected the growth of both rhizobacteria. Root exudates from salt-stressed plants of C. macrophylla (salt tolerant) induced an increase in bacterial growth higher than that obtained from Carrizo citrange exudates (salt sensitive). Root exudates from heat-stressed plants also had a positive effect on bacterial growth, which was more evident in the heat-sensitive C. macrophylla. These results reveal that the growth of these rhizobacteria can be modulated through citrus root exudates and can change depending on both the stress conditions as well as the genotype. Biosensors P. putida KT2442 (pMIS5) and Novosphingobium sp. HR1a (pPAH) were used to test the presence of proline and salicylates in root exudates by measuring β-galactosidase activity. This activity increased in the presence of root exudates obtained from stressed plants to a higher extent in the case of exudates obtained from the genotype resistant to each particular stress, indicating that those root exudates contain larger quantities of proline and salicylates, as it has been described previously. Our data reveals that both P. putida KT2442 (pMIS5) and Novosphingobium sp. HR1a (pPAH), could be used as biosensors of plant stress.
植物不断向根际释放根分泌物。这些化合物负责与其他生物体（包括植物、真菌或细菌）进行不同的（正或负）相互作用。在这项工作中，评估了来自体外培养的柑橘植物的根分泌物对两种根际细菌（假单胞菌 KT2440 和新鞘氨醇单胞菌 HR1a）的影响。根分泌物是从对盐和热胁迫敏感程度不同的两种柑橘基因型的植物中获得的，并且对两种根际细菌的生长有不同的影响。来自盐胁迫下的大翼橙（耐盐）植株的根分泌物诱导细菌生长的增加高于来自 Carrizo 甜橙的根分泌物。来自热胁迫下的植物的根分泌物也对细菌生长有积极影响，在敏感的大翼橙中更为明显。这些结果表明，这些根际细菌的生长可以通过柑橘根分泌物进行调节，并且可以根据胁迫条件和基因型而变化。使用生物传感器假单胞菌 KT2442（pMIS5）和新鞘氨醇单胞菌 HR1a（pPAH）来通过测量β-半乳糖苷酶活性来测试根分泌物中脯氨酸和水杨酸的存在。在存在来自胁迫植物的根分泌物的情况下，该活性增加，在抵抗每种特定胁迫的基因型的根分泌物的情况下增加幅度更大，表明那些根分泌物含有更多量的脯氨酸和水杨酸，如先前所述。我们的数据表明，假单胞菌 KT2442（pMIS5）和新鞘氨醇单胞菌 HR1a（pPAH）都可以用作植物胁迫的生物传感器。
