Enhanced monoterpene emission in transgenic orange mint (Mentha × piperita f. citrata) overexpressing a tobacco lipid transfer protein (NtLTP1)

• Published in: Planta 2020-09, Vol.252 (3), p.44-44, Article 44
• Main Authors: Hwang, Hwan-Su, Adhikari, Prakash Babu, Jo, Hye-Jeong, Han, Jung Yeon, Choi, Yong Eui
• Format: Article
• Language: English
• Subjects: Acetic acid; Agriculture; Antibodies; Biomedical and Life Sciences; Carrier Proteins - genetics; Diterpenes; Ecology; Emission; Emissions; Exudates; Exudates and Transudates - metabolism; Exudation; Forestry; Fruits; Gas chromatography; Gas Chromatography-Mass Spectrometry; Gene Expression Regulation, Plant; Genetic transformation; Genomics; Headspace; Immunoblotting; Life Sciences; Linalyl acetate; Lipids; Mass spectrometry; Mass spectroscopy; Mentha - genetics; Mentha - metabolism; Mentha piperita citrata; Monoterpenes; Monoterpenes - metabolism; Monoterpenoids; Nicotiana - genetics; Original Article; Plant Sciences; Plants, Genetically Modified; Polyclonal antibodies; Polymerase chain reaction; Proteins; Scanning electron microscopy; Solid phase methods; Solid phases; Tobacco; Transgenic plants; Trichomes; Trichomes - metabolism; Volatile compounds; Volatile Organic Compounds - analysis; Volatile Organic Compounds - metabolism
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-020-03447-6

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.