NtCycB2基因表达对烟草腺毛发生的影响

烟草腺毛是烟草表皮细胞的特化结构，对烟株抗性及烟叶品质具有重要影响。为探索烟草腺毛密度的分子调控途径，本文对烟草B型细胞周期蛋白基因NtCycB2进行了同源克隆和生物信息学分析，并对其表达特性和生物学功能进行研究。结果表明该基因包含333bp的编码区，编码110个氨基酸，该序列在栽培烟草不同类型、不同品种间高度保守，但与SlCycB2和AtCycB2同源性分别为71.05%和52.38%。RT-PCR分析表明NtCycB2在叶面腺毛和花中的表达水平较高，并受到盐、温度、MeJA等逆境信号的诱导；分别利用基因过表达和基因编辑技术获得了NtCycB2过量表达和敲除株系；植株腺毛形态学观察发现NtCycB2过表达植株腺毛密度显著减少，基因敲除植株分泌型腺毛密度显著增加，而非分泌型腺毛变化不大，该研究表明NtCycB2对烟草分泌型腺毛发生具有明显的负调控作用，在烟草腺毛密度分子调控和叶面化学定向改良中具有较大潜力。 

Effects of NtCycB2 expression on tobacco trichomes

Tobacco trichome, as a specialized structure of tobacco epidermal cells, has an important influence on plant resistance and leaf quality. In order to explore the molecular regulation pathway for the density of tobacco trichome, t homologous cloning and bioinformatics analysis of tobacco B-type cyclin gene NtCycB2 were carried out, and the expression characteristics and biological functions were studied. Results showed that NtCycB2 contained a 333bp coding region and encoded 110 amino acids. NtCycB2 sequence was highly conserved among cultivated tobacco varieties and has 71.05% and 52.38% homology with SlCycB2 and AtCycB2, respecitvely. RT-PCR analysis showed that NtCycB2 was highly expressed in leaf trichome and flowers, and was induced by stress signals such as NaCl, temperature and MeJA. The NtCycB2 overexpression line and NtCycB2 knock-out line were obtained using transgenic technology and CRISPR-Cas9. Morphological observation of trichome showed that density of trichome was reduced significantly in overexpression lines, while density of glandular trichome was increased significantly in knockout lines and non-glandular trichome showed a little change, which indicated that NtCycB2 acted as a negative regulator for morphogenesis of glandular trichome and played an important role in tobacco leaf chemical orientation improvement.