Drought is a major abiotic stress that limits plant growth and development. Adaptive mechanisms have evolved to mitigate drought stress, in-cluding the capacity to adjust water loss rate and to modify the morphology and structure of the epidermis. Here, we show that the expression of CmNF-YB8, encoding a nuclear factor Y (NF-Y) B-type subunit, is lower under drought conditions in chrysanthemum (Chrysanthemum morifolium). Transgenic chrysanthemum lines in which transcript levels of CmNF-YB8 were reduced by RNA interference (CmNF-YB8-RNAi) exhibited enhanced drought resistance relative to control lines, whereas lines overexpressing CmNF-YB8 (CmNF-YB8-OX) were less tolerant to drought. Compared to wild type (WT), CmNF-YB8-RNAi plants showed reduced stomatal opening and a thicker epidermal cuticle that correlated with their water loss rate. We also identified genes involved in stomatal adjustment (CBL-interacting protein kinase 6, CmCIPK6) and cuticle biosynthesis (CmSHN3) that are more highly expressed in CmNF-YB8-RNAi lines than in WT, CmCIPK6 being a direct downstream target of CmNF-YB8. Virus-induced gene si-lencing of CmCIPK6 or CmSHN3 in the CmNF-YB8-RNAi background abolished the effects of CmNF-YB8-RNAi on stomatal closure and cu-ticle deposition, respectively. CmNF-YB8 thus regulates CmCIPK6 and CmSHN3 expression to alter stomatal movement and cuticle thickness in the leaf epidermis, thereby affecting drought resistance.

Tianle Wang;Qian Wei;Zhiling Wang;Wenwen Liu;Xin Zhao;Chao Ma;Junping Gao;Yanjie Xu;Bo Hong

State Key Laboratory of Agrobiotechnology,Beijing Key Laboratory of Development and Quality Control of Ornamental Crops,Department of Ornamental Horticulture,College of Horticulture,China Agricultural University,Beijing 100193,China;Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm,College of Forestry and Landscape Architecture,South China Agricultural University,Guangzhou 510642,China

植物学报（英文版）

[1]Tianle Wang;Qian Wei;Zhiling Wang;Wenwen Liu;Xin Zhao;Chao Ma;Junping Gao;Yanjie Xu;Bo Hong-.CmNF-YB8 affects drought resistance in chrysanthemum by altering stomatal status and leaf cuticle thickness)[J].植物学报（英文版）,2022(03):741-755

CmNF,YB8,CmCIPK6,CmSHN3,lencing

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