Tobacco NtLTP1, a glandular‐specific lipid transfer protein, is required for lipid secretion from glandular trichomes

Abstract

SUMMARYGlandular trichomes are the phytochemical factories of plants, and they secrete a wide range of commercially important natural products such as lipids, terpenes and flavonoids. Herein, we report that the Nicotiana tabacum LTP1 (NtLTP1) gene, which is specifically expressed in long glandular trichomes, plays a role in lipid secretion from trichome heads. NtLTP1 mRNA is abundantly transcribed in trichomes, but NtLTP3, NtLTP4 and NtLTP5 are not. In situ hybridization revealed that NtLTP1 mRNAs accumulate specifically in long trichomes and not in short trichomes or epidermal cells. X-gluc staining of leaves from a transgenic plant expressing the NtLTP1 promoter fused to a GUS gene revealed that NtLTP1 protein accumulated preferentially on the tops of long glandular trichomes. GFP fluorescence from transgenic tobacco plants expressing an NtLTP1-GFP fusion protein was localized at the periphery of cells and in the excreted liquid droplets from the glandular trichome heads. In vitro assays using a fluorescent 2-p-toluidinonaphthalene-6-sulfonate probe indicated that recombinant NtLTP1 had lipid-binding activity. The overexpression of NtLTP1 in transgenic tobacco plants resulted in the increased secretion of trichome exudates, including epicuticular wax. In transgenic NtLTP1-RNAi lines, liquid secretion from trichomes was strongly reduced, but epicuticular wax secretion was not altered. Moreover, transgenic tobacco plants overexpressing NtLTP1 showed increased protection against aphids. Taken together, these data suggest that NtLTP1 is abundantly expressed in long glandular trichomes, and may play a role in lipid secretion from long glandular trichomes.

Rethinking how volatiles are released from plant cells

“…In plants, LTPs have recently been shown to function in the export of wax lipids and diterpenes from the plasma membrane, across the cell wall, to the cuticle [71][72][73][74]. Given that LTPs generally lack substrate specificity, it is possible that the same LTPs may also be transporting VOCs to neighboring cells, intercellular spaces (in some cases for release via stomata), or the cuticle.…”

Plant Glandular Trichomes: Natural Cell Factories of High Biotechnological Interest

“…In addition to trichome-specific EST resources, numerous glandular trichome-specific gene promoters have been reported in the literature for a variety of plants, including (but not restricted to) Antirrhinum majus, A. annua, C. sativus, H. lupulus, Mentha spp., N. tabacum, S. lycopersicum, and S. habrochaites (Okada and Ito, 2001;Wang et al, 2002Wang et al, , 2011Wang et al, , 2013Gutiérrez-Alcalá et al, 2005;Liu et al, 2006;Jaffé et al, 2007;Kim et al, 2008;Shangguan et al, 2008;Ennajdaoui et al, 2010;Choi et al, 2012;Sallaud et al, 2012;Spyropoulou et al, 2014;Kortbeek et al, 2016;Laterre et al, 2017;Vining et al, 2017;for review, see Tissier, 2012b). It is worth noting that most of these trichome-specific promoters are active in mature glandular trichomes (mostly in glandular cells at the tip of the trichome).…”

A wheat lipid transfer protein 3 could enhance the basal thermotolerance and oxidative stress resistance of Arabidopsis

“…The OsLTP110 protein could inhibit the germination of Pyricularia oryzae spores in vitro (Ge et al, 2003) and overexpression of the LTP gene could bring a substantial resistance to biotic stresses. For instance, transgenic tobacco overexpressing either the TaLTP3F1, HvLTP2 (Hordeum vulgare) and NtLTP1 (Nicotiana tabacum) genes showed fungal, bacterial and aphid resistance, respectively (Choi et al, 2012;Kirubakaran et al, 2008;Molina and García-Olmedo, 2003). In addition, nsLTP genes could respond to abiotic stresses including NaCl, drought, cold and wounding (Cameron et al, 2006;Torres-Schumann et al, 1992;Yubero-Serrano et al, 2003), and recently it has been shown that ZmLTP3 and AtLTP3 could improve plant survival under salt and drought stresses, respectively (Guo et al, 2013;Zou et al, 2013).…”