[P4] Crop Genetics and Physiology

[P4-03] Histone Acetyltransferase GCN5 Regulates the Expression of OsRBCS3 and OsRBCS5, Rubisco Small Subunit Genes, in Response to Nitrogen Supply in Rice (Oryza sativa L.)

*Nominated for Presentation Awards

^○Shicheng Feng¹, Fumiya Miyamoto², Sakae Agarie³, Kazuyuki Saitou⁴ (1.Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, China, 2.Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Japan, 3.Faculty of Agriculture (Graduate School), Kyushu University, Japan, 4.Faculty of Agriculture (Graduate School), Kyushu University, Japan)

Nitrogen is a primary component of plant substances. Nitrogen deficiency leads to slow and stunted growth and chlorosis. Five Ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (RBCS) genes identified in the rice genome are designated as OsRBCS1,2,3,4 and 5. In this study, we investigated the relationship between the expression of GCN5, a GNAT-type histone acetyltransferase gene, and RBCS genes. OsRBCS1 transcripts were not detectable. The mRNA levels of OsRBCS2, OsRBCS3, OsRBCS4, and OsRBCS5 in leaf blades were increased by nitrogen supply, but the incremental ratio of OsRBCS5 was much lower than those of other RBCS multigene family members. The mRNA level of GCN5 was increased by nitrogen supply. To study whether GCN5 regulates the expression of RBCS genes, we produced overexpression transformants of GCN5 under the control of the maize ubiquitin promoter and the CaMV 35S promoter, and knockdown transformants of GCN5 by RNAi. The expression of GCN5 doesn't correlate with that of OsRBCS2 or OsRBCS4, but it has a significant positive correlation with that of OsRBCS3 and OsRBCS5. Furthermore, under the same expression level of GCN5, the expression level of OsRBCS3 was higher than that of OsRBCS5. These results suggest that GCN5 regulates the expression of OsRBCS3 and OsRBCS5 specifically in response to nitrogen supply.