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Title: CLONING AND CHARACTERIZATION OF FLOWER DEVELOPMENT GENES IN PAPAYA

Author
item YU, Q - UNIVERSITY OF HAWAII
item MING, RAY - HARC
item Moore, Paul

Submitted to: CTAHR Student Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: 3/15/2003
Publication Date: 4/24/2003
Citation: Yu, Q., Ming, R., Moore, P.H. 2003. Cloning and characterization of flower development genes in papaya. 15th Annual CTAHR Student Research Symposium (Abstracts) p.30. 2003.

Interpretive Summary: ABSTRACT ONLY

Technical Abstract: Instability of papaya flowers, revealed by environmentally influenced sex reversal and stamen carpellody, results in malformed fruit that is unmarketable. Based on knowledge of flower development in the model plants Antirrhirum and Arabidopsis, we are characterizing homologous genes associated with carpel development in papaya. The Arabidopsis class C organ identity gene AGAMOUS has a papaya homolog named PAG that shares 85% identity with AGAMOUS within the MADS box and K box domains. Genomic Southern analysis showed that papaya has only one copy of PAG that is expressed at high level in carpels. The Arabidopsis gene LEAFY, a positive regulator of AGAMOUS, has a papaya homolog PFL that shares 65% identity with LFY. PFL encodes a protein sharing 71% identity with the LFY homologs of the two tree species California sycamore (Platanus racemosa) and black cottonwood (Populus trichocarpal). Despite extensive sequence similarity in two conserved regions, the proline-rich and acidic motifs differ between PFL and its LFY counterparts from other plants. This difference may not affect the gene function as demonstrated by research on the Pinus radiate LFY homolog Needly. Genomic and BAC Southern analyses indicate that the PAG, PFL exists as a single copy in the papaya genome. In situ hybridization result showed that PFL is expressed at a relatively low level in the shoot apical meristem of very young seedlings, but it is expressed at a high level in the floral meristem. In Arabidopsis, cis-regulatory sequences of AGAMOUS are located in the second intron that contains the binding site of its direct activators of LEAFY. The second intron of PAG is being subcloned and sequenced.