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Article|02 Feb 2022|OPEN
PbrROP1/2-elicited imbalance of cellulose deposition is mediated by a CrRLK1L-ROPGEF module in the pollen tube of Pyrus 
Xiaobing Kou1 , Peng Cao1 , Qianke He1 , Peng Wang1 , Shaoling Zhang1 and Juyou Wu,1 ,
1Centre of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, No 6. Tongwei Road, Nanjing, 210095, China
*Corresponding author. E-mail: juyouwu@njau.edu.cn

Horticulture Research 9,
Article number: uhab034 (2022)
doi: https://doi.org/10.1093/hr/uhab034
Views: 308

Received: 17 May 2021
Revised: 11 Oct 2021
Accepted: 21 Oct 2021
Published online: 02 Feb 2022

Abstract

Pollen tube growth is critical for the sexual reproduction of flowering plants. Catharanthus roseus receptor-like kinases (CrRLK1L) play an important role in plant sexual reproduction, pollen tube growth, and male and female gametophyte recognition. Here, we identified a CrRLK1L protein in pear (Pyrus bretschneideri), PbrCrRLK1L13, which is necessary for normal tip growth of the pollen tube. When PbrCrRLK1L13 was knocked down, the pollen tube grew faster. Interaction analysis showed that the kinase domain of PbrCrRLK1L13 interacted with the C-terminal region of PbrGEF8, and PbrCrRLK1L13 activated the phosphorylation of PbrGEF8 in vitro. Furthermore, PbrROP1 and PbrROP2 were the downstream targets of PbrCrRLK1L13-PbrGEF8. When we knocked down the expression of PbrCrRLK1L13PbrGEF8, or PbrROP1/2, the balance of cellulose deposition in the pollen tube wall was disrupted. Considering these factors, we proposed a model for a signaling event regulating pear pollen tube growth. During pear pollen tube elongation, PbrCrRLK1L13 acted as a surface regulator of the PbrROP1 and PbrROP2 signaling pathway via PbrGEF8 to affect the balance of cellulose deposition and regulate pear pollen tube growth.