Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, 29682 Roscoff Cedex, France.
Proc Natl Acad Sci U S A. 2011 Jul 12;108(28):11518-23. doi: 10.1073/pnas.1102274108. Epub 2011 Jun 27.
The brown alga Ectocarpus siliculosus has a haploid-diploid life cycle that involves an alternation between two distinct generations, the sporophyte and the gametophyte. We describe a mutant, ouroboros (oro), in which the sporophyte generation is converted into a functional, gamete-producing gametophyte. The life history of the mutant thus consists of a continuous reiteration of the gametophyte generation. The oro mutant exhibited morphological features typical of the gametophyte generation and accumulated transcripts of gametophyte generation marker genes. Genetic analysis showed that oro behaved as a single, recessive, Mendelian locus that was unlinked to the IMMEDIATE UPRIGHT locus, which has been shown to be necessary for full expression of the sporophyte developmental program. The data presented here indicate that ORO is a master regulator of the gametophyte-to-sporophyte life cycle transition and, moreover, that oro represents a unique class of homeotic mutation that results in switching between two developmental programs that operate at the level of the whole organism.
褐藻(Ectocarpus siliculosus)具有单倍体-二倍体的生命周期，涉及两个不同世代的交替，即孢子体和配子体。我们描述了一个突变体，oro(oro)，其中孢子体世代被转化为具有功能的、产生配子的配子体。因此，突变体的生活史由配子体世代的连续重复组成。oro 突变体表现出典型的配子体世代的形态特征，并积累了配子体世代标记基因的转录本。遗传分析表明，oro 表现为一个单一的、隐性的、孟德尔基因座，与 IMMEDIATE UPRIGHT 基因座不连锁，后者已被证明是充分表达孢子体发育程序所必需的。这里提出的数据表明，ORO 是配子体到孢子体生命周期转变的主要调节因子，而且，oro 代表了一类独特的同源突变体，导致在两个在整个生物体水平上运作的发育程序之间进行切换。
