An AP2 family gene CBX1 is involved in mycorrhizal symbiosis and growth of Lotus japonicus. APETALA 2 (AP2) transcriptional regulator is highly conserved in plants. CBX1 from Lotus japonicus is a member of AP2 family. AMF (Arbuscular mycorrhizal fungi) inoculation experiment demonstrated that expression of CBX1 was significantly induced by AMF. Further promoter analysis showed that the - 764 to - 498 bp region of the CBX1 promoter containing CTTC motif is the AMF responsive region. Functional analysis of cbx1 mutant suggested CBX1 is critical for mycorrhizal symbiosis, especially for arbuscule formation. Moreover, under noncolonized condition, overexpression of CBX1 reduced the root length of L. japonicus but increased the size of root system and shoot length, whereas cbx1 mutant reduced the root size and shoot length, but not effect on root length. In addition, cbx1 altered activity of monolignol biosynthetic gene and increased lignin levels. Collectively, these data indicated that CBX1 is a positive regulator of symbiotic activity and plays roles in the growth of L. japonicus.

中文翻译：

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APETALA 2 转录因子 CBX1 是菌根共生和莲藕生长的调节剂。

AP2家族基因CBX1参与了莲藕的菌根共生和生长。APETALA 2 (AP2) 转录调节因子在植物中高度保守。Lotus japonicus 的 CBX1 是 AP2 家族的成员。AMF（丛枝菌根真菌）接种实验表明AMF能显着诱导CBX1的表达。进一步的启动子分析表明，含有 CTTC 基序的 CBX1 启动子的 - 764 至 - 498 bp 区域是 AMF 响应区域。cbx1 突变体的功能分析表明 CBX1 对菌根共生至关重要，尤其是对于丛枝的形成。此外，在非定殖条件下，CBX1 的过表达减少了日本血吸虫的根长，但增加了根系的大小和枝条长度，而 cbx1 突变体减少了根大小和枝条长度，但对根长度没有影响。此外，cbx1 改变了 monolignol 生物合成基因的活性并增加了木质素水平。总之，这些数据表明CBX1是共生活性的正调节因子，在日本血吸虫的生长中发挥作用。