The Expression Pattern Of The APETALA2 Group Genes In Rice

The AP2/ERF is the largest transcription factor gene family in plants, and plays an important role in flower development.The AP2/ERF family genes have a DNA-binding domain that consists of approximately 68 conserved amino acid residues,named of AP2 domain. According to the number of AP2 domain, the AP2/ERF family can be devided into three subfamily : AP2 subfamily,ERF subfamily and RAV subfamily;AP2 subfamily is composed of AP2 group,ANT group and basalAP2 group . AP2 group genes contain two AP2 domain R1 and R2 , and they possess one microRNA172 (miRNA172)-binding site . The gene function of AP2-like genes has been studied in Arabidopsis , which plays a role in floral organ identity, stem cell maintenance and seed mass.There is different expression pattern in flower development between monocot and eudocot.Rice is one of model plants in monocot and human have gained the whole genomic sequence ,which provide the advantages to research on rice.Therefore, we researched the expression patten of the AP2 group genes in rice1. We performed phylogenetic analysis for 26 AP2-like genes that belong to the AP2 subfamily of rice, according to 18 AP2-like genes in Arabidopsis . The AP2 group contains five genes in rice, includeing Os07g13170, Os03g60430, Os06g43220, Os04g55560and Os05g03040.2. The expression patterns of these AP2-like genes in rice have been characterized. The result of RT-PCR indicates that these AP2-like genes express young roots , young leaves and calli; there is no signal of Os03g60430 in seedlings; the weak signals of 5 genes are found in mature leaves.3. Based on the AP2 gene function in Arabidopsis, we presume that has the similar function in rice, so we get a series of rice spikelet.The result indicate that hybridazation signals of Os03g60430 and Os06g43220 were detected in primary branch meristem; in the secondary branch primodial, Os07g13170, Os03g60430 and Os05g03040 have expressed; all of five genes have expressed in ovules and theae.4. There are different expression patterns in rice AP2 genes ;there are different expression levels in different organs. 03g60430 is expressed in leaves, roots, inflorescences, primary branch meristems, glumes, floral meristems, stamens, carpels, ovules and thecae. Its duplicate, SNB, displays very similar expression pattern; 06g43220 is expressed in leaves, roots, bract primordia, ovules and thecae. Its putative ortholog in maize, GLOSSY15, is expressed in juvenile leaves . 04g55560 is expressed in leaves, roots, ovules, and thecae. However, its putative ortholog in Arabidopsis, AP2, is expressed in all four types of floral organs, ovules, inflorescence meristems, leaves, and stems. These indicate the ortholog genes maybe have different function.The divergence of expression may lead in the differentiation of function, which may contribute to biological innovations.