Saleem Aansa Rukya, Brunetti Cecilia, Khalid Azeem, Della Rocca Gianni, Raio Aida, Emiliani Giovanni, De Carlo Anna, Mahmood Tariq, Centritto Mauro
Department of Earth and Environmental Sciences, Bahria University Islamabad Campus, Islamabad, Pakistan.
Tree and Timber Institute, National Research Council of Italy, Via Madonna del Piano, Sesto Fiorentino, Firenze, Italy.
PLoS One. 2018 Feb 15;13(2):e0191218. doi: 10.1371/journal.pone.0191218. eCollection 2018.
Drought is one of the major constraints limiting agricultural production worldwide and is expected to increase in the future. Limited water availability causes significant effects to plant growth and physiology. Plants have evolved different traits to mitigate the stress imposed by drought. The presence of plant growth-promoting rhizobacteria (PGPR) could play an important role in improving plant performances and productivity under drought. These beneficial microorganisms colonize the rhizosphere of plants and increase drought tolerance by lowering ethylene formation. In the present study, we demonstrate the potential to improve the growth of velvet bean under water deficit conditions of two different strains of PGPR with ACCd (1-Aminocyclopropane-1-Carboxylate deaminase) activity isolated from rainfed farming system. We compared uninoculated and inoculated plants with PGPR to assess: a) photosynthetic performance and biomass; b) ACC content and ethylene emission from leaves and roots; c) leaf isoprene emission. Our results provided evidence that under drought conditions inoculation with PGPR containing the ACCd enzyme could improve plant growth compared to untreated plants. Ethylene emission from roots and leaves of inoculated velvet bean plants was significantly lower than uninoculated plants. Moreover, isoprene emission increased with drought stress progression and was higher in inoculated plants compared to uninoculated counterparts. These findings clearly illustrate that selected PGPR strains isolated from rainfed areas could be highly effective in promoting plant growth under drought conditions by decreasing ACC and ethylene levels in plants.
干旱是限制全球农业生产的主要因素之一，预计未来干旱情况还会加剧。可用水资源有限会对植物生长和生理产生重大影响。植物已经进化出不同的特性来减轻干旱带来的压力。植物促生根际细菌（PGPR）的存在可能在提高干旱条件下植物的性能和生产力方面发挥重要作用。这些有益微生物定殖在植物根际，通过降低乙烯生成来提高耐旱性。在本研究中，我们展示了从雨养农业系统中分离出的两种具有ACC脱氨酶（1-氨基环丙烷-1-羧酸脱氨酶）活性的PGPR菌株在水分亏缺条件下改善毛蔓豆生长的潜力。我们将未接种和接种PGPR的植物进行比较，以评估：a）光合性能和生物量；b）叶片和根系中的ACC含量以及乙烯排放；c）叶片异戊二烯排放。我们的结果表明，在干旱条件下，与未处理的植物相比，接种含有ACC脱氨酶的PGPR可以改善植物生长。接种毛蔓豆植物的根和叶的乙烯排放显著低于未接种的植物。此外，异戊二烯排放随着干旱胁迫的加剧而增加，接种植物的异戊二烯排放高于未接种的植物。这些发现清楚地表明，从雨养地区分离出的选定PGPR菌株通过降低植物中的ACC和乙烯水平，在干旱条件下促进植物生长方面可能非常有效。
