Drought is a critical environmental factor which constrains plant survival and growth. Genetic en-gineering provides a credible strategy to improve drought tolerance of plants. Here, we generated transgenic poplar lines expressing the isopentenyl transferase gene (IPT) under the driver of PtRD26 promoter (PtRD26pro-IPT). PtRD26 is a senescence and drought-inducible NAC transcription factor. PtRD26pro-IPT plants displayed multiple pheno-types, including improved growth and drought tolerance. Transcriptome analysis revealed that auxin biosynthesis pathway was activated in the PtRD26pro-IPT plants, leading to an increase in auxin contents. Biochemical analysis revealed that ARABIDOPSIS RESPONSE REGULATOR10 (PtARR10), one of the type-B ARR transcription factors in the cytokinin pathway, was induced in PtRD26pro-IPT plants and directly regulated the transcripts of YUCCA4 (PtYUC4) and YUCCA5 (PtYUC5), two enzymes in the auxin biosynthesis pathway. Overexpression of PtYUC4 enhanced drought tolerance, while simultaneous silencing of PtYUC4/5 evidently attenuated the drought toler-ance of PtRD26pro-IPT plants. Intriguingly, PtYUC4/5 displayed a conserved thioredoxin reductase activity that is required for drought tolerance by deterring reactive oxygen species accumulation. Our work reveals the molecular basis of cytokinin and auxin interactions in response to environmental stresses, and shed light on the improvement of drought tolerance without a growth penalty in trees by molecular breeding.

Hou-Ling Wang;Qi Yang;Shuya Tan;Ting Wang;Yi Zhang;Yanli Yang;Weilun Yin;Xinli Xia;Hongwei Guo;Zhonghai Li

National Engineering Laboratory for Tree Breeding,College of Biological Sciences and Technology,Beijing Forestry University,Beijing 100083,China;Department of Biology,Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes,Southern University of Science and Technology(SUSTech),Shenzhen 518055,China

植物学报（英文版）

[1]Hou-Ling Wang;Qi Yang;Shuya Tan;Ting Wang;Yi Zhang;Yanli Yang;Weilun Yin;Xinli Xia;Hongwei Guo;Zhonghai Li-.Regulation of cytokinin biosynthesis using PtRD26pro-IPT module improves drought tolerance through PtARR10-PtYUC4/5-mediated reactive oxygen species removal in Populus)[J].植物学报（英文版）,2022(03):771-786

PtRD26pro,PtARR10,PtYUC4,gineering,PtRD26,ARABIDOPSIS,REGULATOR10,YUCCA4,YUCCA5,PtYUC5

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