College of tobacco science, Henan Agricultural University, 63 Nongye Road, Zhengzhou, 450002, China.
Plant Mol Biol. 2022 Jan;108(1-2):65-76. doi: 10.1007/s11103-021-01222-z. Epub 2021 Nov 26.
NtCycB2 negatively regulates the initiation of tobacco long stalk glandular trichomes and influences the expression of diterpenoid biosynthesis- and environmental stress resistance-related genes. Many asterid plants possess multicellular trichomes on their surface, both glandular and non-glandular. The CycB2 gene plays a key role in multicellular trichome initiation, but has distinct effects on different types of trichomes; its mechanisms remain unknown. In tomato (Solanum lycopersicum), SlCycB2 negatively regulates non-glandular trichome formation, but its effects on glandular trichomes are ambiguous. In this study, we cloned the SlCycB2 homolog of Nicotiana tabacum, NtCycB2, and analyzed its effect on three types of trichomes, long stalk glandular trichomes (LGT), short stalk glandular trichomes (SGT), and non-glandular trichomes (NGT). Knocking out NtCycB2 (NtCycB2-KO) promoted LGT formation, while overexpression of NtCycB2 (NtCycB2-OE) decreased LGT density. SGT and NGT were not significantly influenced in either NtCycB2-KO or NtCycB2-OE plants, indicating that NtCycB2 regulated only LGT formation in tobacco. In addition, compared with NtCycB2-OE and control plants, NtCycB2-KO plants produced more trichome exudates, including diterpenoids and sugar esters, and exhibited stronger aphid resistance. To further elucidate the function of NtCycB2, RNA-Seq analysis of the NtCycB2-KO, NtCycB2-OE, and control plants was conducted. 2,552 and 1,933 differentially expressed genes (DEGs) were found in NtCycB2-KO and NtCycB2-OE plants, respectively. Gene Ontology analysis of the common DEGs revealed that ion transport, carbohydrate and amino acid metabolism, photosynthesis, and transcription regulation processes were significantly enriched. Among these DEGs, diterpenoid biosynthesis genes were upregulated in NtCycB2-KO plants and downregulated in NtCycB2-OE plants. Two MYB transcription factors and several stress resistance-related genes were also identified, suggesting they may participate in regulating LGT formation and aphid resistance.
NtCycB2 负调控烟草长梗腺毛的起始，影响二萜生物合成和环境胁迫抗性相关基因的表达。许多星形植物在其表面具有多细胞毛，包括腺毛和非腺毛。CycB2 基因在多细胞毛起始中起关键作用，但对不同类型的毛有不同的影响；其机制尚不清楚。在番茄（Solanum lycopersicum）中，SlCycB2 负调控非腺毛的形成，但对腺毛的影响尚不明确。在本研究中，我们克隆了烟草的 SlCycB2 同源物 NtCycB2，并分析了其对三种毛，长梗腺毛（LGT）、短梗腺毛（SGT）和非腺毛（NGT）的影响。敲除 NtCycB2（NtCycB2-KO）促进了 LGT 的形成，而过表达 NtCycB2（NtCycB2-OE）则降低了 LGT 的密度。在 NtCycB2-KO 或 NtCycB2-OE 植物中，SGT 和 NGT 均无明显变化，表明 NtCycB2 仅调控烟草 LGT 的形成。此外，与 NtCycB2-OE 和对照植物相比，NtCycB2-KO 植物产生了更多的毛分泌物，包括二萜和糖酯，并表现出更强的抗蚜性。为了进一步阐明 NtCycB2 的功能，对 NtCycB2-KO、NtCycB2-OE 和对照植物进行了 RNA-Seq 分析。在 NtCycB2-KO 和 NtCycB2-OE 植物中分别发现了 2552 个和 1933 个差异表达基因（DEGs）。对共同 DEGs 的基因本体论分析表明，离子运输、碳水化合物和氨基酸代谢、光合作用和转录调控过程显著富集。在这些 DEGs 中，二萜生物合成基因在 NtCycB2-KO 植物中上调，在 NtCycB2-OE 植物中下调。还鉴定了两个 MYB 转录因子和几个与胁迫抗性相关的基因，表明它们可能参与调控 LGT 的形成和抗蚜性。
