Submitted to: Plant Animal and Microbe Genomes Conference
Publication Type: Abstract Only
Publication Acceptance Date: 10/3/2003
Publication Date: 1/9/2004
Citation: Yu, Q., Moore, P.H., Ackerman, C.M., Ming, R. 2004. Cloning and characterization of floral homeotic genes in papaya. Plant Animal and Microbe Genomes Conference XII. P597, p. 220. 2004
Interpretive Summary: abstract only
Technical Abstract: Instability of papaya flowers, revealed by environmentally influenced sex reversal and stamen carpellody, results in unmarketable malformed fruit. Based on knowledge of flower development in the model plants Antirrhirum and Arabidopsis, we characterized homologous genes associated with carpel development in papaya. The papaya homolog of the Arabidopsis C class gene AGAMOUS, PAG, 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 a high level in carpels. The papaya homolog of LEAFY, PFL, a positive regulator of AGAMOUS, 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 in other plants. This difference may not affect the gene function as indicated by research on the Pinus radiata LFY homolog Needly. Genomic and BAC Southern analyses indicate that like PAG, PFL exists as a single copy in the papaya genome. In situ hybridization results 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. Hua1is another regulator of Arabidopsis stamen and carpel identities, and its papaya homolog, Phua1, shares about 82% identity with the Hua1 gene. Understanding the papaya floral development process could lead to strategies for controlling papaya fruit development.