Characterization of HoMADS 1 and its induction by plant hormones during in vitro ovule development in Hyacinthus orientalis L.

Abstract

To understand the molecular mechanism of ovule development, a MADS box gene, HoMADS 1 , has been isolated from the ovule tissues of Hyacinthus . Sequence comparison showed that HoMADS 1 is highly homologous to both class C and D genes. Furthermore, phylogenetic analysis suggests that HoMADS 1 is most likely a class D MADS box gene. RNA hybridization revealed that HoMADS 1 was exclusively expressed in the ovules. Over-expressing HoMADS 1 in transgenic Arabidopsis plants produced ectopic carpelloid structures, including ovules, indicating that HoMADS 1 is involved in the determination of carpel and ovule identities. Interestingly, during in vitro flowering, no HoMADS 1 mRNA was detected in the floral tissues at high level hormones in the media. However, HoMADS 1 mRNA accumulated in the floral tissues when the regenerated flowers were transferred to the media containing low level hormones which could induce in vitro ovule formation. Our data suggest that the induction of HoMADS 1 by plant hormones may play important roles during ovule initiation and development in the regenerated flower. Whether HoMADS 1 expression is also regulated by cytokinin and auxin during ovule development in planta remains to be investigated.

Molecular Mechanism Regulating Floral Architecture in Monocotyledonous Ornamental Plants

“…The conversion of sepals into carpelloid structures and petals into staminoid structures occurred in A. thaliana transformants overexpressing LMADS2 (Tzeng et al, 2002); therefore, lily D-lineage genes may have stronger effects than C-lineage genes in A. thaliana (Hsu et al, 2010). C-and D-lineage genes (HAG1 and HoMADS1, respectively) were also isolated and characterized in Hyacinthus orientalis (Li et al, 2002;Xu et al, 2004). HAG1 was expressed in stamen and carpel, whereas HoMADS1 mRNA accumulated exclusively in ovules.…”

“…HAG1 was expressed in stamen and carpel, whereas HoMADS1 mRNA accumulated exclusively in ovules. Overexpression of HAG1 and HoMADS1 in A. thaliana resulted in carpel-like organs with ovules in whorl 1 and staminoid petals or a petal-less form in whorl 2 (Li et al, 2002;Xu et al, 2004).…”

“…Gene expression analyses in some orchid species such as Phalaenopsis equestris, C. ensifolium, and Orchis italica showed that the C-and D-lineage genes were expressed primarily in the column and ovaries (Acri-Nunes-Miranda and Mondragón-Palomino, 2014; Chen et al, 2012b;Hsu et al, 2010;Salemme et al, 2013;Skipper et al, 2006;Song et al, 2006;Wang et al, 2011;Xu et al, 2006). The D-lineage gene expression pattern in orchids differs from that of LMADS2 (L. longiflorum) and HoMADS1 (H. orientalis), which were expressed exclusively in ovules (Tzeng et al, 2002;Xu et al, 2004). Although the orchid C-and D-lineage genes are expressed in column and ovaries, the expression level of D-lineage genes is higher in ovaries at late flower development stages in C. ensifolium, O. italica, and Phalaenopsis hybrid (Acri-Nunes-Miranda and Mondragón-Palomino, 2014; Salemme et al, 2013;Wang et al, 2011).…”

Spatiotemporal expression of duplicate AGAMOUS orthologues during floral development in Phalaenopsis

“…In monocots, AG-like genes have been studied in rice (Kang et al 1995(Kang et al , 1998, maize (Mena et al 1996), lily (Tzeng et al 2002;Benedito et al 2004), Hyacinthus (Li et al 2002;Xu et al 2004), and Asparagus (Yun et al 2004a,b). While phylogenetic positions of D-lineage AG-like genes from grass plants are unclear because the phylogenetic positions of these genes in NJ tree does not coincide in those of 4).…”

Cloning and transcription analysis of an AGAMOUS- and SEEDSTICK ortholog in the orchid Dendrobium thyrsiflorum (Reichb. f.)

“…In A. thaliana ovule identity has diversified further since this process is promoted by a complex collaboration of the C-(AGAMOUS/AG), D-(SEEDSTICK/STK) and the so-called SHATTERPROOF (SHP) genes (Pinyopich et al, 2003). Although C-and D lineage orthologs have been studied in both grasses (Kang et al, 1998;Kyozuka and Shimamoto, 2002;Lopez-Dee et al, 1999;Mena et al, 1996;Schmidt et al, 1993;Theissen et al, 1995) and petaloid monocots like Lilium longiflorum (Benedito et al, 2004;Tzeng et al, 2002) and Hyacinthus orientalis (Li et al, 2002;Xu et al, 2004) very little is known about the function of these genes in the remaining monocots.…”