Yu Hao, Wang Xiao-Ling, Sun Run-Hong, Qi Lin, Song Peng, Wang Tong-Chao
College of Agronomy, Henan University of Science and Technology, Luoyang 471023, China.
Henan Key Laboratory for Control of Crop Diseases and Insect Pests, IPM Key Laboratory in Southern Part of North China for Ministry of Agriculture, Institute of Plant Protection Research, Henan Academy of Agricultural Sciences, Zhengzhou 450099, China.
Microorganisms. 2024 Nov 21;12(12):2383. doi: 10.3390/microorganisms12122383.
This study investigates the mechanisms driving maize compensatory growth upon post-drought, to reveal how the root's original cytokinins are regulated by the two-fold roles of heterotrophic bacteria with ammonia-oxidizing (HAOB) capabilities. The HAOB' dual roles encompass influencing root cytokinin synthesis and transport through nitrification and a direct pathway. Experiment 1 involved introducing the application of varying amounts of NO to the roots to examine how nitrification affects cytokinin roots-to-leaves transport. Results demonstrate that the 30-40 mmol·L NO concentration had ideal effects on enhancing post-drought growth in maize by facilitating cytokinin synthesis and transport. In experiment 2, an HAOB strain, S2_8_1, was utilized and NO was supplemented alongside HAOB inoculation to assess the joint impacts of nitrification and the direct pathway on the production and transportation of cytokinins. Results demonstrate that the HAOB strain S2_8_1 increases nitrification rates in rhizosphere soil, thereby promoting the transport of cytokinins from roots to leaves. In addition, the HAOB strain promotes root cytokinin transport to leaves autonomously, showcasing its direct pathway. Inoculation with the HAOB strain increased leaf cytokinin content and improved water use efficiency compared to the addition of NO; however, the combination of NO and HAOB strains resulted in a synergistic effect and further improvement. These findings elucidate how HAOB can enhance maize compensatory growth through its dual roles, presenting promising applications in agriculture.
本研究探究了干旱后驱动玉米补偿性生长的机制，以揭示具有氨氧化能力的异养细菌（HAOB）的双重作用如何调节根系原有的细胞分裂素。HAOB的双重作用包括通过硝化作用和一条直接途径影响根系细胞分裂素的合成与运输。实验1通过向根部施加不同量的NO，来研究硝化作用如何影响细胞分裂素从根到叶的运输。结果表明，30 - 40 mmol·L的NO浓度通过促进细胞分裂素的合成和运输，对增强玉米干旱后的生长具有理想效果。在实验2中，使用了HAOB菌株S2_8_1，并在接种HAOB的同时补充NO，以评估硝化作用和直接途径对细胞分裂素产生和运输的联合影响。结果表明，HAOB菌株S2_8_1提高了根际土壤中的硝化速率，从而促进了细胞分裂素从根到叶的运输。此外，HAOB菌株自主促进根系细胞分裂素向叶片的运输，展示了其直接途径。与添加NO相比，接种HAOB菌株增加了叶片细胞分裂素含量并提高了水分利用效率；然而，NO与HAOB菌株的组合产生了协同效应并进一步改善。这些发现阐明了HAOB如何通过其双重作用增强玉米的补偿性生长，在农业中具有广阔的应用前景。
