Graduate school of Bioscience and Biotechnology, Chubu University, Kasugai, Aichi 487-8501, Japan.
Plant Sci. 2011 Jul;181(1):39-46. doi: 10.1016/j.plantsci.2011.03.007. Epub 2011 Mar 22.
The Arabidopsis ENHANCER OF SHOOT REGENERATION (ESR)1 and ESR2 genes are thought to play critical roles in in vitro shoot regeneration. In this study, we investigated the functions and expression patterns of ESR1 and ESR2 during shoot regeneration by using their mutants and promoter-reporter systems. Shoot regeneration efficiencies of esr1 esr2 double mutants from hypocotyl explants decreased drastically; although the effects on shoot regeneration of the esr1 single mutation were much less marked than those of the esr2 single mutation, especially from root explants, their effects were additive. We found that ESR1 was initially expressed 1 day after transfer onto shoot-inducing medium (SIM), compared with 4 days for ESR2 expression. These results suggest that the functions of ESR1 and ESR2 in shoot regeneration are not redundant, even though they encode similar transcription factors and the ESR2 gene substituted with an ESR1 coding region complements the esr2 mutation. We also found that ESR1 expression was localized to a small number of cells in the lateral root meristem (LRM)-like structures, and the ESR1-expressing cells appeared to proliferate to form shoot apical meristem (SAM)-like structures. Thus, ESR1 may be involved in the change of LRM to SAM in tissue culture.
拟南芥增强再生（ESR）1 和 ESR2 基因被认为在体外再生中发挥关键作用。在这项研究中，我们通过使用它们的突变体和启动子报告系统，研究了 ESR1 和 ESR2 在再生过程中的功能和表达模式。从下胚轴外植体中，esr1 esr2 双突变体的再生效率急剧下降；尽管 esr1 单突变对再生的影响远小于 esr2 单突变，特别是从根外植体，但它们的影响是累加的。我们发现 ESR1 在转移到诱导再生培养基（SIM）后 1 天表达，而 ESR2 表达则需要 4 天。这些结果表明，即使 ESR1 和 ESR2 编码相似的转录因子，并且 ESR2 基因用 ESR1 编码区取代可以弥补 esr2 突变，它们在再生中的功能也不是冗余的。我们还发现 ESR1 表达定位于侧根分生组织（LRM）样结构中的少数细胞，并且表达 ESR1 的细胞似乎增殖形成茎尖分生组织（SAM）样结构。因此，ESR1 可能参与了组织培养中 LRM 向 SAM 的变化。
