Serrano-Cartagena J, Candela H, Robles P, Ponce M R, Pérez-Pérez J M, Piqueras P, Micol J L
División de Genética, Universidad Miguel Hernández, Campus de San Juan, 03550 Alicante, Spain.
Genetics. 2000 Nov;156(3):1363-77. doi: 10.1093/genetics/156.3.1363.
In an attempt to identify genes involved in the control of leaf morphogenesis, we have studied 13 Arabidopsis thaliana mutants with curled, involute leaves, a phenotype herein referred to as Incurvata (Icu), which were isolated by G. Röbbelen and belong to the Arabidopsis Information Service Form Mutants collection. The Icu phenotype was inherited as a single recessive trait in 10 mutants, with semidominance in 2 mutants and with complete dominance in the remaining 1. Complementation analyses indicated that the studied mutations correspond to five genes, representative alleles of which were mapped relative to polymorphic microsatellites. Although most double-mutant combinations displayed additivity of the Icu phenotypes, those of icu1 icu2 and icu3 icu4 double mutants were interpreted as synergistic, which suggests that the five genes studied represent three independent genetic operations that are at work for the leaf to acquire its final form at full expansion. We have shown that icu1 mutations are alleles of the Polycomb group gene CURLY LEAF (CLF) and that the leaf phenotype of the icu2 mutant is suppressed in an agamous background, as is known for clf mutants. In addition, we have tested by means of multiplex RT-PCR the transcription of several floral genes in Icu leaves. Ectopic expression of AGAMOUS and APETALA3 was observed in clf and icu2, but not in icu3, icu4, and icu5 mutants. Taken together, these results suggest that CLF and ICU2 play related roles, the latter being a candidate to belong to the Polycomb group of regulatory genes. We propose that, as flowers evolved, a new major class of genes, including CLF and ICU2, may have been recruited to prevent the expression of floral homeotic genes in the leaves.
为了鉴定参与叶片形态发生控制的基因，我们研究了13个拟南芥突变体，这些突变体的叶片卷曲、内卷，在此将这种表型称为内曲叶（Icu），它们由G. Röbbelen分离得到，属于拟南芥信息服务形态突变体库。Icu表型在10个突变体中作为单隐性性状遗传，在2个突变体中表现为半显性，在其余1个突变体中表现为完全显性。互补分析表明，所研究的突变对应于五个基因，其代表性等位基因相对于多态性微卫星进行了定位。虽然大多数双突变组合表现出Icu表型的加性效应，但icu1 icu2和icu3 icu4双突变体的表型被解释为协同效应，这表明所研究的五个基因代表了三个独立的遗传作用，它们在叶片充分展开以获得最终形态的过程中发挥作用。我们已经表明，icu1突变是多梳蛋白家族基因卷曲叶（CLF）的等位基因，并且icu2突变体的叶片表型在无配子背景下受到抑制，这与clf突变体的情况相同。此外，我们通过多重RT-PCR检测了Icu叶片中几个花器官基因的转录情况。在clf和icu2突变体中观察到了AGAMOUS和APETALA3的异位表达，但在icu3、icu4和icu5突变体中未观察到。综合这些结果表明，CLF和ICU2发挥相关作用，后者可能是多梳蛋白调控基因家族的候选成员。我们提出，随着花的进化，可能招募了包括CLF和ICU2在内的一类新的主要基因，以防止花同源异型基因在叶片中表达。
