The Potential of Transgenic Hybrid Aspen Plants with a Recombinant Lac Gene from the Fungus Trametes hirsuta to Degrade Trichlorophenol.

Abstract

Objective: Laccases are known to be able to degrade phenolic compounds to simpler components. The main objective of our study was to analyze this property in transgenic aspen plants carrying the laccase gene Lac from Trametes hirsuta which can be potentially used in soil phytoremediation. Methods: We created transgenic aspen plants carrying the laccase gene Lac from Trametes hirsute using the agrobacterial transformation of stem explants with the pBI-Lac vector containing the Lac gene from the white rot fungus T. hirsuta 072 (NCBI GenBank accession number KP027478). Transgenic plants were micropropagated and cultivated in vitro in lines. The degradation of 2,4,6-trichlorophenol (2,4,6-TCP) by plant roots was analyzed by mass-spectrometry with electron ionization using a gas chromatograph. Results: Although plants have their own laccases, those of fungal origin are more effective. All transgenic plants that expressed the recombinant gene degraded 2,4,6-TCP more effectively than non-transformed plants in the control (the degradation efficiency ranged 92 to 98% versus 82% in non-transformed control). Line 47Lac8 demonstrated a 16% higher efficiency than the non-transformed plants in the control. There was also an inverse relationship between the viability of a transgenic line and its level of expression of the recombinant gene. Thus, line 47Lac4 was not viable under native conditions, probably due to lignin synthesis disruptions during the initiation of secondary tissues. This is confirmed by changes in the expression of native genes of lignin biosynthesis. The rest of the transgenic lines did not differ significantly from control in wood growth and biochemistry. The transgenic plant roots were shown to preserve the ability to express the Lac gene ex vitro. Conclusions: Three transgenic lines (47Lac5, 47Lac8, and 47Lac23) with the Lac gene can be recommended for use in soil phytoremediation.