AOM3 and AOM4 : two MADS box genes expressed in reproductive structures of Asparagus officinalis

Abstract

The MADS box genes participate in different steps of vegetative and reproductive plant development, including the most important phases of the reproductive process. Here we describe the isolation and characterisation of two Asparagus officinalis MADS box genes, AOM3 and AOM4. The deduced AOM3 protein shows the highest degree of similarity with ZAG3 and ZAG5 of maize, OsMADS6 of rice and AGL6 of Arabidopsis thaliana. The deduced AOM4 protein shows the highest degree of similarity with AOM1 of asparagus, the SEP proteins of Arabidopsis and the rice proteins OsMADS8, OsMADS45 and OsMADS7. The high level of identity between AOM1 and AOM4 made impossible the preparation of probes specific for one single gene, so the hybridisation signal previously described for AOM1 is probably due to the expression of both genes. The expression profile of AOM3 and AOM1/AOM4 during flower development is identical, and similar to that of the SEP genes. Asparagus genes, however, are expressed not only in flower organs, but also in the different meristem present on the apical region of the shoot during the flowering season: the apical meristem and the three lateral meristems emerging from the leaf axillary region that will give rise to flowers and lateral inflorescences during flowering season, and to phylloclades and branches during the subsequent vegetative phase. The expression of AOM3 and AOM1/AOM4 in these meristems appears to be correlated with the reproductive function of the apex as the hybridisation signal disappears when the apex switches to vegetative function.

Evolution ofAGL6-likeMADS Box Genes in Grasses (Poaceae): Ovule Expression Is Ancient and Palea Expression Is New

“…Similar results have been obtained in zag3 in situ hybridization and, moreover, zag3 mutants produce extra carpels in the ear (Thompson et al, 2009). These data are consistent with many other studies that have detected expression in carpels and ovules in angiosperms (Ma et al, 1991;Mena et al, 1995;Rounsley et al, 1995;Moon et al,1999;Tsuchimoto et al, 2000;Boss et al, 2002;Pelucchi et al, 2002;Hsu et al, 2003;Losa et al, 2004;Petersen et al, 2004;Chanderbali et al, 2006;Fan et al, 2007), except in Persea and Magnolia where RT-PCR failed to detect AGL6 expression in the carpel . Curiously, yeast two-hybrid data fail to show any interaction of AGL6-like proteins with B and C class MADS box proteins in rice (Moon et al, 1999), whereas the maize AGL6 homolog, ZAG3, does interact with the AG homolog, ZAG1 (Thompson et al, 2009).…”

“…Expression in microsporangia was detected in gymnosperms as well as in several angiosperms but not in all (Ma et al, 1991;Mena et al, 1995;Rounsley et al, 1995;Tandre et al, 1995;Liu and Podila, 1997;Mouradov et al, 1998;Moon et al,1999;Winter et al, 1999;Tsuchimoto et al, 2000;Boss et al, 2002;Pelucchi et al, 2002;Hsu et al, 2003;Losa et al, 2004;Petersen et al, 2004;Chanderbali et al, 2006;Fan et al, 2007). Our in situ hybridizations showed that AGL6-like genes are expressed in stamens only in J. ascendens, the grass S. angustifolia in Anomochlooideae, and in Ehrhartoideae.…”

“…In non-Poales monocots and in eudicots, mRNA of AGL6 orthologs is also detected in floral meristems prior to floral organ formation (Boss et al, 2002;Hsu et al, 2003;Losa et al, 2004;Fan et al, 2007). All these results together indicate that expression of AGL6 in floral meristems has been conserved at least since the origin of the angiosperms.…”

“…AGL6-like genes are expressed exclusively in the second whorl in species that have flowers with novel structures such as the cap in Vitis vinifera (Boss et al, 2002) or the lip in Oncidium (Hsu et al, 2003); otherwise, AGL6 expression was detected in both whorl 1 and whorl 2 (Ma et al, 1991;Tsuchimoto et al, 2000;Losa et al, 2004;Kim et al, 2005;Chanderbali et al, 2006;Fan et al, 2007). In grasses, previous studies suggest that AGL6 orthologs are expressed in lodicules as well as in the palea (Mena et al, 1995;Moon et al, 1999;Aiguo and Griffin, 2002;Petersen et al, 2004;Thompson et al, 2009).…”

“…We supplemented our own data with published sequence and expression data for Hyacinthus orientalis (Hyacinthaceae) (Fan et al, 2007), Asparagus officinalis (Asparagaceae) (Losa et al, 2004), and Z. mays (Thompson et al, 2009). …”