Functional Analysis of Calcium-dependent Protein Kinase CPK14 in Pollen Tube Growth

doi:10.13560/j.cnki.biotech.bull.1985.2019-0219

Abstract

Abstract: The purpose of the study is to reveal the biological function of CPK14（calcium-dependent protein kinase 14）in pollen tube polar growth. Based on the available microarray database,the expression heat-map of pollen-specific CPK was depicted. The constitutively active CPK14（CA-CPK14）was constructed by removing the auto-inhibitor and Ca²⁺ binding domain at the C-terminal and retaining the complete kinase and N-terminal variable regions. The resulting construct（full-length CPK14,CA-CPK14 or GFP alone）was transiently expressed in tobacco pollen tubes via particle bombardment,and the overexpression phenotypes of transformed tubes were compared and analyzed. The effect of CA-CPK14 on the activity of ROP1 was analyzed by co-expression experiment of CA-CPK14 and GFP-RIC4ΔC（a marker of active ROP1）. The results showed that eight pollen-specific CPKs（including CPK14）were identified,and they were highly expressed in mature pollen grains and less expressed in other tissues. CPK14 overexpression caused a swelling tip of pollen tubes,while CA-CPK14（continuous activation and lack of Ca²⁺ regulation）inhibited the germination and growth of pollen tube. ROP1 was a key regulator of pollen tube growth. The expression of CA-CPK14 inhibited the accumulation and distribution of active ROP1 maker（GFP-RIC4ΔC）at the top of pollen tube. These results suggest that CPK14 may play a role in the ROP1-mediated regulation mechanism of pollen tube growth.

Key words: pollen tube, polar growth, calcium-dependent protein kinase, Ca²⁺ signaling pathway

ZHOU Li-ming, LU Xin-rui, MA Sheng-wei, FANG Wei. Functional Analysis of Calcium-dependent Protein Kinase CPK14 in Pollen Tube Growth[J]. Biotechnology Bulletin, 2019, 35(6): 55-61.

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