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Article|19 May 2023|OPEN
4-methylumbelliferone (4-MU) enhances drought tolerance of apple by regulating rhizosphere microbial diversity and root architecture
Dehui Zhang1,2 ,† , Jieqiang He1 ,† , Pengda Cheng1 , Yutian Zhang1 , Abid Khan3 , Shicong Wang1 , Zhongxing Li1 , Shuang Zhao1 , Xiangqiang Zhan1 , Fengwang Ma1 and Xuewei Li1 , Qingmei Guan,1 ,
1State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling 712100, China
2College of Life Science, Northwest A&F University, Yangling 712100, China
3Department of Horticulture, The University of Haripur, Haripur 22620, Pakistan
*Corresponding author. E-mail:
Both authors contributed equally to the study.

Horticulture Research 10,
Article number: uhad099 (2023)
Views: 116

Received: 05 Dec 2022
Accepted: 04 May 2023
Published online: 19 May 2023


The dwarfing rootstocks-mediated high-density apple orchard is becoming the main practice management. Currently, dwarfing rootstocks are widely used worldwide, but their shallow root system and drought sensitivity necessitate high irrigation requirements. Here, the root transcriptome and metabolome of dwarfing (M9-T337, a drought-sensitive rootstock) and vigorous rootstocks (Malus sieversii, a drought-tolerant species, is commonly used as a rootstock) showed that a coumarin derivative, 4-Methylumbelliferon (4-MU), was found to accumulate significantly in the roots of vigorous rootstock under drought condition. When exogenous 4-MU was applied to the roots of dwarfing rootstock under drought treatment, the plants displayed increased root biomass, higher root-to-shoot ratio, greater photosynthesis, and elevated water use efficiency. In addition, diversity and structure analysis of the rhizosphere soil microbial community demonstrated that 4-MU treatment increased the relative abundance of putatively beneficial bacteria and fungi. Of these, PseudomonasBacillusStreptomyces, and Chryseolinea bacterial strains and AcremoniumTrichoderma, and Phoma fungal strains known for root growth, or systemic resistance against drought stress, were significantly accumulated in the roots of dwarfing rootstock after 4-MU treatment under drought stress condition. Taken together, we identified a promising compound—4-MU, as a useful tool, to strengthen the drought tolerance of apple dwarfing rootstock.