Rijpkema Anneke S, Zethof Jan, Gerats Tom, Vandenbussche Michiel
Plant Genetics, IWWR, Radboud University Nijmegen, 6525 ED, Nijmegen, The Netherlands.
Plant J. 2009 Oct;60(1):1-9. doi: 10.1111/j.1365-313X.2009.03917.x. Epub 2009 May 12.
SEPALLATA (SEP) MADS-box genes are required for the regulation of floral meristem determinacy and the specification of sepals, petals, stamens, carpels and ovules, specifically in angiosperms. The SEP subfamily is closely related to the AGAMOUS LIKE6 (AGL6) and SQUAMOSA (SQUA) subfamilies. So far, of these three groups only AGL6-like genes have been found in extant gymnosperms. AGL6 genes are more similar to SEP than to SQUA genes, both in sequence and in expression pattern. Despite the ancestry and wide distribution of AGL6-like MADS-box genes, not a single loss-of-function mutant exhibiting a clear phenotype has yet been reported; consequently the function of AGL6-like genes has remained elusive. Here, we characterize the Petunia hybrida AGL6 (PhAGL6, formerly called PETUNIA MADS BOX GENE4/pMADS4) gene, and show that it functions redundantly with the SEP genes FLORAL BINDING PROTEIN2 (FBP2) and FBP5 in petal and anther development. Moreover, expression analysis suggests a function for PhAGL6 in ovary and ovule development. The PhAGL6 and FBP2 proteins interact in in vitro experiments overall with the same partners, indicating that the two proteins are biochemically quite similar. It will be interesting to determine the functions of AGL6-like genes of other species, especially those of gymnosperms.
SEPALLATA（SEP）MADS盒基因对于调控花分生组织的确定性以及萼片、花瓣、雄蕊、心皮和胚珠的特化是必需的，特别是在被子植物中。SEP亚家族与AGAMOUS LIKE6（AGL6）和SQUAMOSA（SQUA）亚家族密切相关。到目前为止，在现存的裸子植物中仅发现了这三个组中的AGL6类基因。AGL6基因在序列和表达模式上都比SQUA基因更类似于SEP基因。尽管AGL6类MADS盒基因具有古老的起源和广泛的分布，但尚未报道过一个表现出明确表型的功能丧失突变体；因此，AGL6类基因的功能仍然难以捉摸。在这里，我们对矮牵牛AGL6（PhAGL6，以前称为矮牵牛MADS盒基因4/pMADS4）基因进行了表征，并表明它在花瓣和花药发育中与SEP基因FLORAL BINDING PROTEIN2（FBP2）和FBP5发挥冗余功能。此外，表达分析表明PhAGL6在子房和胚珠发育中具有功能。在体外实验中，PhAGL6和FBP2蛋白总体上与相同的伙伴相互作用，这表明这两种蛋白在生化性质上非常相似。确定其他物种，特别是裸子植物中AGL6类基因的功能将是很有趣的。
