Cruz de Carvalho Ricardo, Carreiras João Albuquerque, Matos Ana Rita, Caçador Isabel, Duarte Bernardo
MARE-Marine and Environmental Sciences Centre & ARNET-Aquatic Research Network Associated Laboratory, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisbon, Portugal.
CE3C-Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisbon, Portugal.
Plants (Basel). 2025 Apr 16;14(8):1227. doi: 10.3390/plants14081227.
The duration, frequency, and intensity of drought events in the Mediterranean region pose increasing threats to conventional crop production. Consequently, eco-friendly and sustainable development approaches should aim to address future food production goals. Halophytes, such as J. Woods, represent promising cash crops for cultivation in conjunction with novel biofertilization strategies involving plant growth-promoting bacteria (PGPB). In the present study, the physiological fitness of under various drought conditions, with and without marine PGPB inoculation, was evaluated to enhance the resilience of this cash crop halophyte under water-limited conditions. Our results indicate that PGPB inoculation significantly decreased water loss under extreme drought, with non-inoculated plants showing a water content (WC) of 59%, while in inoculated plants, the decrease in WC was lower at 77%. Furthermore, PGPB inoculation significantly enhanced the photochemistry of the plant, which maintained higher active oxygen-evolving complexes and a greater ability for complete closure of reaction centers under severe and extreme drought, thus demonstrating an improved capacity for light energy utilization in photosynthesis even under water-limited conditions. Furthermore, bioaugmented plants generally exhibited improved osmoregulation through increased yet appropriate accumulation of proline, a major osmolyte, and higher relative water content in the stem compared to the corresponding non-inoculated plants. Drought stress similarly modified the fatty acid profile in both plant groups, resulting in increased membrane stability due to reduced fluidity. However, PGPB-inoculated plants demonstrated a higher capacity for mitigation of oxidative stress, primarily through enhanced activities of superoxide dismutase, which is crucial for the scavenging of harmful reactive oxygen species (ROS). This, along with improvements in energy use and dissipation, as evidenced by photochemistry, reveals a multi-dimensional mechanism for drought tolerance in bioaugmented plants. Metabolic changes, particularly in PGPB-inoculated plants, clearly demonstrate the potential of these bacteria to be utilized in the enhancement of drought tolerance in . Moreover, these data elucidate the complex metabolic aspects regarding photochemistry, osmoregulation, and oxidative stress that should be considered when phenotyping plants for drought tolerance, given the increasing water scarcity worldwide scenario.
地中海地区干旱事件的持续时间、频率和强度对传统作物生产构成了日益严重的威胁。因此，生态友好型和可持续发展方法应致力于实现未来的粮食生产目标。盐生植物，如J. Woods，与涉及促进植物生长的细菌（PGPB）的新型生物施肥策略相结合，是很有前景的经济作物。在本研究中，评估了在有无海洋PGPB接种的情况下，该盐生经济作物在各种干旱条件下的生理适应性，以增强其在水分受限条件下的恢复力。我们的结果表明，接种PGPB在极端干旱条件下显著减少了水分流失，未接种的植物水分含量（WC）为59%，而接种的植物水分含量下降幅度较小，为77%。此外，接种PGPB显著增强了植物的光化学作用，在严重和极端干旱条件下，其保持了更高的活性放氧复合体以及反应中心完全关闭的更强能力，从而表明即使在水分受限条件下，光合作用中光能利用能力也有所提高。此外，与相应的未接种植物相比，生物强化植物通常通过增加脯氨酸（一种主要的渗透调节剂）的适当积累以及茎中更高的相对含水量，表现出更好的渗透调节能力。干旱胁迫同样改变了两个植物组中的脂肪酸谱，由于流动性降低导致膜稳定性增加。然而，接种PGPB的植物表现出更高的减轻氧化应激的能力，主要是通过增强超氧化物歧化酶的活性，这对于清除有害的活性氧（ROS）至关重要。这一点，连同光化学所证明的能量利用和耗散的改善，揭示了生物强化植物耐旱的多维机制。代谢变化，特别是在接种PGPB的植物中，清楚地表明了这些细菌在增强该植物耐旱性方面的利用潜力。此外，考虑到全球水资源日益稀缺的情况，这些数据阐明了在对植物进行耐旱表型分析时应考虑的关于光化学、渗透调节和氧化应激的复杂代谢方面。
