Lv Qiang, Hao Ruo-Yu, Wang Xiao-Ling, Zhou Li-Ju, Qi Lin, Song Peng
College of Agronomy, Henan University of Science and Technology, Luoyang, Henan, 471003, China.
School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, Jiangsu, 210000, China.
BMC Biotechnol. 2025 Jul 11;25(1):71. doi: 10.1186/s12896-025-01006-z.
Water scarcity threatens global food security, making drought resilience in crops like maize crucial. In response to this challenge, this study investigates the potential of heterotrophic ammonia-oxidizing bacteria (HAOB) to enhance maize compensatory growth under post-drought limited rewatering conditions. Specifically, we focus on the dual mechanism of HAOB in modulating cytokinin synthesis and transport, aiming to develop an innovative agricultural biotechnology to support sustainable crop production. The S2_8_1 HAOB strain was used across two experiments. Experiment 1 investigated varying NO levels' effects on cytokinin translocation from roots to leaves under limited rewatering. Experiment 2 combined NO supplementation with HAOB inoculation to assess HAOB's twofold function in promoting compensatory growth under limited rewatering. The results showed that optimal NO levels (20-30 mmol·L for limited rewatering) enhanced maize growth, root-to-shoot cytokinin translocation, and leaf cytokinin levels under limited rewatering. Notably, inoculation with HAOB outperformed these effects, demonstrating a more robust impact on cytokinin delivery and plant growth. This confirmed HAOB's twofold mechanism: Nitrification pathway - HAOB enhances rhizospheric NO₃⁻ availability, thereby stimulating cytokinin biosynthesis in roots and its translocation to leaves. Non-nitrification pathway - HAOB further promotes cytokinin translocation through mechanisms independent of soil NO₃⁻ increase. Sufficient rewatering increased rhizosphere nitrification rates, boosting root cytokinin translocation to leaves, thereby supported compensatory growth. Limited rewatering reduced rhizosphere nitrification, cytokinin translocation, and compensatory growth. However, HAOB overcame these constraints through its twofold function, enhancing cytokinin translocation and improving water use efficiency by more than fourfold, successfully promoting compensatory growth even under limited rewatering. Additionally, NO supplementation alleviated some limitations by increasing rhizosphere NO, but HAOB inoculation proved more effective, highlighting its superior role. This twofold function of HAOB strain significantly elevated cytokinin levels in leaves, supporting compensatory growth under limited rewatering. This biotechnology offers high agricultural potential, particularly in water-scarce regions, by improving drought resilience and yield stability.
水资源短缺威胁着全球粮食安全，因此提高玉米等作物的抗旱能力至关重要。为应对这一挑战，本研究调查了异养氨氧化细菌（HAOB）在干旱后有限复水条件下增强玉米补偿生长的潜力。具体而言，我们关注HAOB在调节细胞分裂素合成和运输方面的双重机制，旨在开发一种创新的农业生物技术以支持可持续作物生产。S2_8_1 HAOB菌株用于两项实验。实验1研究了在有限复水条件下不同NO水平对细胞分裂素从根向叶转运的影响。实验2将NO添加与HAOB接种相结合，以评估HAOB在有限复水条件下促进补偿生长的双重功能。结果表明，最佳NO水平（有限复水时为20 - 30 mmol·L）在有限复水条件下增强了玉米生长、根到地上部的细胞分裂素转运以及叶片细胞分裂素水平。值得注意的是，接种HAOB的效果优于这些影响，对细胞分裂素传递和植物生长表现出更强的影响。这证实了HAOB的双重机制：硝化途径 - HAOB提高根际NO₃⁻可用性，从而刺激根中细胞分裂素生物合成及其向叶的转运。非硝化途径 - HAOB通过独立于土壤NO₃⁻增加的机制进一步促进细胞分裂素转运。充足复水提高了根际硝化速率，促进根细胞分裂素向叶的转运，从而支持补偿生长。有限复水降低了根际硝化、细胞分裂素转运和补偿生长。然而，HAOB通过其双重功能克服了这些限制，增强了细胞分裂素转运并将水分利用效率提高了四倍多，即使在有限复水条件下也成功促进了补偿生长。此外，添加NO通过增加根际NO缓解了一些限制，但接种HAOB被证明更有效，突出了其优越作用。HAOB菌株的这种双重功能显著提高了叶片中的细胞分裂素水平，支持了有限复水条件下的补偿生长。这种生物技术通过提高抗旱能力和产量稳定性，在农业上具有很高的潜力，特别是在缺水地区。
