Colombo Monica, Masiero Simona, Vanzulli Silvia, Lardelli Paolo, Kater Martin M, Colombo Lucia
Dipartimento di Biologia, Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy.
Plant J. 2008 Jun;54(6):1037-48. doi: 10.1111/j.1365-313X.2008.03485.x. Epub 2008 Mar 13.
MADS-box transcription factors are key regulators of plant developmental processes. While the function of MIKC (type II) MADS-box genes has been intensively studied, only limited data are available for the other more recently identified classes of MADS-box genes, despite these latter comprising more than 60% of the Arabidopsis MADS-box gene family. Here we describe the function of AGL23, an Arabidopsis type I MADS-box gene belonging to the Malpha subfamily. We show that AGL23 plays an important role during development of the female gametophyte and embryo. The agl23-1 mutant forms a functional megaspore. However, at this stage female gametophyte development is arrested and the megaspore persists during subsequent phases of ovule development. Despite the incomplete penetrance of the female gametophyte defect, plants homozygous for the agl23-1 mutation were never identified. Analysis of developing seeds showed that embryos homozygous for the agl23-1 allele are albino and unable to give rise to viable plants. Electron microscopy analysis revealed that this phenotype is due to the absence of chloroplasts, strongly suggesting that AGL23 is involved in controlling the biogenesis of organelles during embryo development.
MADS盒转录因子是植物发育过程的关键调节因子。虽然MIKC（II型）MADS盒基因的功能已得到深入研究，但对于其他最近鉴定出的MADS盒基因类别，尽管它们占拟南芥MADS盒基因家族的60%以上，但相关数据却很有限。在此，我们描述了AGL23的功能，它是拟南芥中属于Mα亚家族的I型MADS盒基因。我们发现AGL23在雌配子体和胚胎发育过程中发挥重要作用。agl23 - 1突变体形成了功能正常的大孢子。然而，在此阶段雌配子体发育停滞，大孢子在胚珠发育的后续阶段持续存在。尽管雌配子体缺陷的表型不完全一致，但从未鉴定出agl23 - 1突变纯合的植株。对发育种子的分析表明，agl23 - 1等位基因纯合的胚胎呈白化病状态，无法发育成有活力的植株。电子显微镜分析显示，这种表型是由于缺乏叶绿体所致，这强烈表明AGL23参与了胚胎发育过程中细胞器生物合成的调控。
