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Article|03 May 2023|OPEN
Gibberellin biosynthesis is required for CPPU-induced parthenocarpy in melon
Yue Liu1 ,† , Yang Li1 ,† , Huixin Guo1 ,† , Bingsheng Lv1 , Jing Feng1 , Huihui Wang1 , Zhonghua Zhang1 , and Sen Chai,1 ,
1Engineering Laboratory of Genetic Improvement of Horticultural Crops of Shandong Province, College of Horticulture, Qingdao Agricultural University, Qingdao 266109, China
*Corresponding author. E-mail:,
Yue Liu,Yang Li and Huixin Guo contributed equally to the study.

Horticulture Research 10,
Article number: uhad084 (2023)
Views: 148

Received: 10 Jan 2023
Accepted: 18 Apr 2023
Published online: 03 May 2023


Spraying N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU), an exogenous cytokinin (CK) growth regulator, is the conventional method for inducing fruit set during melon (Cucumis melo L.) production; however, the mechanism by which CPPU induces fruit set is unclear. Through histological and morphological observations, fruit size was comparable between CPPU-induced fruits and normal pollinated fruits because CPPU-induced fruits had higher cell density but smaller cell size compared with normal pollinated fruits. CPPU promotes the accumulation of gibberellin (GA) and auxin and decreases the level of abscisic acid (ABA) during fruit set. Moreover, application of the GA inhibitor paclobutrazol (PAC) partially inhibits CPPU-induced fruit set. Transcriptome analysis revealed that CPPU-induced fruit set specifically induced the GA-related pathway, in which the key synthase encoding gibberellin 20-oxidase 1 (CmGA20ox1) was specifically upregulated. Further study indicated that the two-component response regulator 2 (CmRR2) of the cytokinin signaling pathway, which is highly expressed at fruit setting, positively regulates the expression of CmGA20ox1. Collectively, our study determined that CPPU-induced melon fruit set is dependent on GA biosynthesis, providing a theoretical basis for the creation of parthenocarpic melon germplasm.