A Plant Plasma Membrane ATP Binding Cassette-Type Transporter Is Involved in Antifungal Terpenoid Secretion

Abstract

ATP binding cassette (ABC) transporters, which are found in all species, are known mainly for their ability to confer drug resistance. To date, most of the ABC transporters characterized in plants have been localized in the vacuolar membrane and are considered to be involved in the intracellular sequestration of cytotoxins. Working on the assumption that certain ABC transporters might be involved in defense metabolite secretion and their expression might be regulated by the concentration of these metabolites, we treated a Nicotiana plumbaginifolia cell culture with sclareolide, a close analog of sclareol, an antifungal diterpene produced at the leaf surface of Nicotiana spp; this resulted in the appearance of a 160-kD plasma membrane protein, which was partially sequenced. The corresponding cDNA (NpABC1) was cloned and shown to encode an ABC transporter. In vitro and in situ immunodetection showed NpABC1 to be localized in the plasma membrane. Under normal conditions, expression was found in the leaf epidermis. In cell culture and in leaf tissues, NpABC1 expression was strongly enhanced by sclareolide and sclareol. In parallel with NpABC1 induction, cells acquired the ability to excrete a labeled synthetic sclareolide derivative. These data suggest that NpABC1 is involved in the secretion of a secondary metabolite that plays a role in plant defense.

ArabidopsisPEN3/PDR8, an ATP Binding Cassette Transporter, Contributes to Nonhost Resistance to Inappropriate Pathogens That Enter by Direct Penetration

“…Among the plant PDR subgroup of ABC transporters, studies of two Nicotiana species transporters, N. plumbaginifolia PDR1/ ABC1 and tobacco (Nicotiana tabacum) PDR1, which are most similar in sequence to the Arabidopsis PDR12, suggest that they may function in the export of toxic secondary plant metabolites and/or in the detoxification of pathogen toxins. Similar to PEN3, the expression of N. tabacum PDR1and N. plumbaginifolia PDR1 is induced by defense-related signals such as pathogen elicitors and methyl jasmonate, and N. plumbaginifolia PDR1 is also induced by the phytoalexin sclareol (Jasinski et al, 2001;Sasabe et al, 2002). Arabidopsis does not produce sclareol; however, PDR12 is induced by fungal pathogens, and plants carrying a T-DNA insertion in PDR12 are reportedly more sensitive to exogenous sclareol and to lead (see Supplemental Table 3 online) (Campbell et al, 2003;Lee et al, 2005).…”

Metabolomics Reveals Novel Pathways and Differential Mechanistic and Elicitor-Specific Responses in Phenylpropanoid and Isoflavonoid Biosynthesis in Medicago truncatula Cell Cultures

“…It is known that secondary metabolites are transported across membranes by specific carrier proteins (Walker et al, 2003;Yazaki, 2005). For example, an ATP-binding cassette-type transporter involved in antifungal terpenpoid secretion from tobacco (Nicotiana tabacum) cell cultures has been identified (Jasinski et al, 2001). We assume that similar transporters are present in Medicago for isoflavones; however, neither specific nor generic isoflavonoid transporters have been identified in this species to date.…”

A petunia ABC protein controls strigolactone-dependent symbiotic signalling and branching

“…The rationale behind the focus on these transporters, of which there are 15 in Arabidopsis 11 , 23 in Oryza sativa (rice) 11 and 23 putative factors in Solanum lycopersicum (tomato) ( Supplementary Fig. 3a), was that they are plasma membrane proteins often found in roots 12 , they are implicated in below-ground plantmicrobe interactions 13,14 , and they have affinities for compounds that are structurally related to strigolactones 8,9,15 . Of six primary candidates, only P. hybrida PDR1 had increased expression in roots that were subjected to either phosphate starvation (Fig.…”