Rice Papers

Nature precedings 2009聽 May

A novel superior factor widely controlling the rice grain quality

from Tokyo University of Science etc.

鑳氫钩鐨勭敓鎴愯繃绋嬩富瑕佸寘鎷偍钘忔穩绮夌殑鍚堟垚鍜岃泲鐧界殑绉疮銆� 杩欎竴杩囩▼褰撳彈鍒伴伃閬囬�嗗鑳佽揩鏃朵緥濡傞珮娓╀細鏀跺埌寮虹儓褰卞搷锛屽洜姝わ紝鍏ㄧ悆姘斿�欏彉鏆栫殑瓒嬪娍浼氬椋熺墿鐨勪骇閲忎骇鐢熸瀬澶у▉鑳� 銆傛穩绮夊悎鎴愬拰铔嬬櫧璐棌閫斿緞涓殑閰剁被鐩镐簰浣滅敤锛岀敓鎴愭按绋昏儦涔筹紝浣嗗叾璋冩帶鏈虹悊杩樹笉鏄庝簡銆傛湰鐮旂┒鍙戠幇浜嗕竴涓柊鐨勮皟鎺у瓙OsCEO1,浣滅敤鏄儦涔冲湪鐏屾祮鏃舵湡鐨勫紩瀵间綋銆俧lo锛�2鐨勮〃鍨嬬被浼间簬鍙楀埌楂樻俯褰卞搷鐨勪骇鐢熺殑绮夎川鎬х姸锛岃鏄庤繖涓�鍩哄洜瀵归珮娓╄儊杩晱鎰� 銆傚flo2鍥句綅鍏嬮殕鍒扮殑OsCEO1涓庡凡鐭ョ殑鍔熻兘鍩哄洜閮戒笉瀛樺湪鍚屾簮鎬э紝瀹冨睘浜庝竴涓潪淇濆畧鐨勫熀鍥犲鏃忥紝缂栫爜1720涓皑鍩洪吀锛屽寘鍚竴涓笁瑙掑洓鑲介噸澶嶅尯锛圱PR锛夛紝鍙兘鍙備笌铔嬬櫧浜掍綔銆傞叺姣嶅弻鏉傛壘鍑�1涓湭鐭ョ殑鏅氭湡鑳氳儙鍙戣偛鍚屾簮铔嬬櫧鍙�1涓亣瀹歨elix-loop-helix铔嬬櫧浣滅敤OsCEO1鐨勭洿鎺ヤ簰浣滃璞★紝缁撴灉涓苟娌℃湁涓庢穩绮夎泲鐧借串钘忓悎鎴愮浉鍏崇殑閰剁被锛岃�屽湪flo2绐佸彉浣撲腑锛屽緢澶氳繖绫荤殑閰讹紝涓昏鏄亣瀹氱殑璋冩帶铔嬬櫧锛岃〃杈句笂閮戒笅璋冦�傛�讳箣锛岀爺绌惰〃鏄庯紝OsCEO1鍙兘鍦ㄦ暣涓儦涔崇敓鎴愰�斿緞鐨勪笂娓歌皟鎺э紝骞跺楂樻俯鑳佽揩鐨勫搷搴旇捣鐫�閲嶈浣滅敤銆�

Synthesis of storage starch and protein accumulation is the main action of endosperm organogenesis in term of the economic importance of rice. This event is strongly disturbed by abiotic stresses such as high temperature; thus, the upcoming global warming will cause a crisis with a great impact on food production1,2. The enzymes for the protein storage and starch synthesis pathway should work in concert to carry out the organogenesis of rice endosperm3鈥�5, but the regulatory mechanism is largely unknown. Here we show that a novel regulatory factor, named OsCEO1, acts as the conductor of endosperm organogenesis during the rice grain filling stage. The physiological properties of floury-endosperm-2 (flo2) mutants showed many similarities to symptoms of grains developed under high-temperature conditions, suggesting important roles of the responsible gene in sensitivity to high-temperature stress. Our map-based cloning identified the responsible gene for the flo2 mutant, OsCEO1, which has no homology to any genes of known function. The OsCEO1 belongs to a novel conserved gene family and encodes a protein composed of 1,720 amino acid residues containing a TPR(tetratricopeptide repeat) motif, which is considered to mediate a protein-protein interaction. The yeast two-hybrid analysis raised an unknown protein showing homology to a late embryogenesis abundant protein and a putative basic helix-loop-helix protein as candidates for the direct interactor for OsCEO1, whereas no enzyme genes for the synthesis of storage substances were detected. The flo2 mutant exhibited reduced expression of several genes for putative regulatory proteins as well as many enzymes involved in storage starch and proteins. These results suggest that OsCEO1 is a superior conductor of the novel regulatory cascade of endosperm organogenesis and may have important roles in the response to high-temperature stress.