Kato Hiroaki, Komeda Yoshibumi, Saito Tamao, Ito Hidetaka, Kato Atsushi
Biosystems Science Course, Graduate School of Life Science, Hokkaido University.
Genes Genet Syst. 2015;90(3):163-74. doi: 10.1266/ggs.90.163.
The acaulis2 (acl2) mutant of Arabidopsis thaliana shows a defect in flower stalk elongation. We identified the mutation point of acl2 by map-based cloning. The ACL2 locus is located within an approximately 320-kb region at around 100 map units on chromosome 1. One nucleotide substitution was detected in this region in the acl2 mutant, but no significant open reading frames were found around this mutation point. When wild-type DNA fragments containing the mutation point were introduced into acl2 mutant plants, some transgenic plants partially or almost completely recovered from the defect in flower stalk elongation. 3'-RACE experiments showed that bidirectional transcripts containing the acl2 mutation point were expressed, and the Plant MPSS database revealed that several small RNAs were produced from this region. Microarray analysis showed that transcription of many genes is activated in flower stalks of acl2 mutant plants. Overexpression of some of these genes caused a dwarf phenotype in wild-type plants. These results suggest the following novel mechanism for control of the elongation of flower stalks. Bidirectional non-coding RNAs are transcribed from the ACL2 locus, and small RNAs are generated from them in flower stalks. These small RNAs repress the transcription of a set of genes whose expression represses flower stalk elongation, and flower stalks are therefore fully elongated.
拟南芥的无茎2（acaulis2，acl2）突变体在花茎伸长方面存在缺陷。我们通过图位克隆确定了acl2的突变位点。ACL2基因座位于第1号染色体上约100个遗传单位处的一个约320 kb的区域内。在acl2突变体的该区域检测到一个核苷酸替换，但在该突变位点周围未发现明显的开放阅读框。当将含有突变位点的野生型DNA片段导入acl2突变体植株时，一些转基因植株从花茎伸长缺陷中部分或几乎完全恢复。3'-RACE实验表明含有acl2突变位点的双向转录本被表达，并且植物MPSS数据库显示从该区域产生了几种小RNA。微阵列分析表明许多基因的转录在acl2突变体植株的花茎中被激活。其中一些基因的过表达在野生型植株中导致矮化表型。这些结果提示了以下控制花茎伸长的新机制。双向非编码RNA从ACL2基因座转录而来，并且在花茎中从小RNA产生。这些小RNA抑制一组抑制花茎伸长的基因的转录，因此花茎得以充分伸长。
