Pollen tube growth is essential for successful double fertilization, which is critical for grain yield in crop plants. Rapid alkalinization factors(RALFs) function as ligands for signal transduction during fertilizati...Pollen tube growth is essential for successful double fertilization, which is critical for grain yield in crop plants. Rapid alkalinization factors(RALFs) function as ligands for signal transduction during fertilization. However, functional studies on RALF in monocot plants are lacking.Herein, we functionally characterized two pollen-specific RALFs in rice(Oryza sativa) using multiple clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated protein 9-induced loss-of-function mutants,peptide treatment, expression analyses, and tag reporter lines. Among the 41 RALF members in rice, OsRALF17 was specifically expressed at the highest level in pollen and pollen tubes.Exogenously applied OsRALF17 or OsRALF19peptide inhibited pollen tube germination and elongation at high concentrations but enhanced tube elongation at low concentrations, indicating growth regulation. Double mutants of OsRALF17 and OsRALF19(ralf17/19) exhibited almost full male sterility with defects in pollen hydration, germination, and tube elongation,which was partially recovered by exogenous treatment with OsRALF17 peptide. This study revealed that two partially functionally redundant OsRALF17 and OsRALF19 bind to Oryza sativa male-gene transfer defective 2(OsMTD2) and transmit reactive oxygen species signals for pollen tube germination and integrity maintenance in rice. Transcriptomic analysis confirmed their common downstream genes, in osmtd2 and ralf17/19. This study provides new insights into the role of RALF, expanding our knowledge of the biological role of RALF in regulating rice fertilization.展开更多
基金supported by grants from the National Research Foundation, Ministry of Education, Science and Technology (2019R1C1C1002636 and RS-2023-00217064 to Y.-J.K., 2021R1A4A2001968 to S.T.K., and 2021M3E5E6025387 and 2021R1A5A1032428 to K.-H.J.)the New Breeding Technologies Development Program (PJ01661002 to K.-H.J.)the Rural Development Administration, Republic of Korea。
文摘Pollen tube growth is essential for successful double fertilization, which is critical for grain yield in crop plants. Rapid alkalinization factors(RALFs) function as ligands for signal transduction during fertilization. However, functional studies on RALF in monocot plants are lacking.Herein, we functionally characterized two pollen-specific RALFs in rice(Oryza sativa) using multiple clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated protein 9-induced loss-of-function mutants,peptide treatment, expression analyses, and tag reporter lines. Among the 41 RALF members in rice, OsRALF17 was specifically expressed at the highest level in pollen and pollen tubes.Exogenously applied OsRALF17 or OsRALF19peptide inhibited pollen tube germination and elongation at high concentrations but enhanced tube elongation at low concentrations, indicating growth regulation. Double mutants of OsRALF17 and OsRALF19(ralf17/19) exhibited almost full male sterility with defects in pollen hydration, germination, and tube elongation,which was partially recovered by exogenous treatment with OsRALF17 peptide. This study revealed that two partially functionally redundant OsRALF17 and OsRALF19 bind to Oryza sativa male-gene transfer defective 2(OsMTD2) and transmit reactive oxygen species signals for pollen tube germination and integrity maintenance in rice. Transcriptomic analysis confirmed their common downstream genes, in osmtd2 and ralf17/19. This study provides new insights into the role of RALF, expanding our knowledge of the biological role of RALF in regulating rice fertilization.
