MAIN CONCLUSION Overexpression of the tobacco lipid transfer protein (NtLTP1) gene in transgenic orange mint resulted in enhanced accumulation of monoterpenes in the cavity of head cells of glandular trichomes, which resulted in enhanced emission of monoterpenes from transgenic orange mints. Plants in the genus Mentha (Lamiaceae) produce volatile oils that accumulate in peltate glandular trichomes in the aerial parts of plants. A lipid transfer protein (NtLTP1) in tobacco showed glandular trichome-specific expression and supported the secretion of diterpenoid lipids from head cells of glandular trichomes (Choi et al., Plant J 70:480-491,2012). Here, we constructed transgenic orange mint (Mentha × piperita f. citrata) overexpressing the tobacco NtLTP1 gene via Agrobacterium-mediated transformation. Transgenic lines of orange mint overexpressing NtLTP1 were confirmed by genomic PCR and RT-PCR. Immunoblotting analysis using an NtLTP1 polyclonal antibody showed clear dark spots at the position of the lipid exudates from tobacco glandular trichomes and the squeezed out lipids from the glandular trichomes of transgenic orange mint. Heads of glandular trichomes in transgenic plants overexpressing the NtLTP1 gene showed a larger diameter than those of the wild-type control. The enhanced size of trichome heads in transgenic orange mint was confirmed by scanning electron microscopy. Volatile components were extracted from wild-type and transgenic orange mint by solid-phase microextraction (SPME) and analyzed by headspace-gas chromatography-mass spectrometry (HS/GC/MS). Linalyl acetate was the most abundant component among the eleven identified monoterpenes in the volatile compounds extracted from both the wild-type and transgenic lines of orange mint. Overexpression of NtLTP1 in transgenic orange mint plants resulted in enhanced emission of volatile monoterpenoids compared with that of volatile monoterpenoids in the wild-type control plants.

中文翻译：

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过度表达烟草脂质转移蛋白 (NtLTP1) 的转基因橙薄荷 (Mentha × piperita f. citrata) 中的单萜排放增强

主要结 薄荷属（唇形科）的植物产生挥发油，这些挥发油在植物地上部分的盾状腺毛中积累。烟草中的脂质转移蛋白 (NtLTP1) 表现出腺毛特异性表达，并支持从腺毛的头部细胞分泌二萜类脂 (Choi 等人, Plant J 70:480-491,2012)。在这里，我们通过农杆菌介导的转化构建了过表达烟草 NtLTP1 基因的转基因橙薄荷 (Mentha × piperita f. citrata)。通过基因组 PCR 和 RT-PCR 证实了过表达 NtLTP1 的橙薄荷转基因品系。使用 NtLTP1 多克隆抗体进行的免疫印迹分析显示，在烟草腺毛的脂质渗出物和转基因橙薄荷腺毛中挤出的脂质位置处有明显的黑点。过表达 NtLTP1 基因的转基因植物中腺毛的头部显示出比野生型对照更大的直径。扫描电子显微镜证实了转基因橙薄荷中毛状体的大小增加。通过固相微萃取 (SPME) 从野生型和转基因橙薄荷中提取挥发性成分，并通过顶空-气相色谱-质谱 (HS/GC/MS) 进行分析。在从橙薄荷的野生型和转基因品系中提取的挥发性化合物中，乙酸芳樟酯是 11 种已鉴定的单萜中含量最高的成分。与野生型对照植物中挥发性单萜类化合物相比，转基因橙薄荷植物中 NtLTP1 的过表达导致挥发性单萜类化合物的排放增加。