title: Lysimachia foenum-graecum Herba Extract, a Novel Biopesticide, Inhibits ABC Transporter Genes and Mycelial Growth of Magnaporthe oryzae.
abstract: To identify a novel biopesticide controlling rice blast disease caused by Magnaporthe oryzae, 700 plant extracts were evaluated for their inhibitory effects on mycelial growth of M. oryzae. The L. foenum-graecum Herba extract showed the lowest inhibition concentration (IC50) of 39.28 μg/ml, which is lower than the IC50 of blasticidin S (63.06 μg/ml), a conventional fungicide for rice blast disease. When treatments were combined, the IC50 of blasticidin S was dramatically reduced to 10.67 μg/ml. Since ABC transporter genes are involved in fungicide resistance of many organisms, we performed RT-PCR to investigate the transcriptional changes of 40 ABC transporter family genes of M. oryzae treated with the plant extract, blasticidin S, and tetrandrine, a recognized ABC transporter inhibitor. Four ABC transporter genes were prominently activated by blasticidin S treatment, but were suppressed by combinational treatment of blasticidin S with the plant extract, or with tetrandrine that didn't show cellular toxicity by itself in this study. Mycelial death was detected via confocal microscopy at 24 h after plant extract treatment. Finally, subsequent rice field study revealed that the plant extract had high control efficacy of 63.3% and should be considered a biopesticide for rice blast disease. These results showed that extract of L. foenum graecum Herba suppresses M. oryzae ABC transporter genes inducing mycelial death and therefore may be a potent novel biopesticide.
authors.affiliation: Faculty of Department of Oriental Pharmaceutical Development, Laboratory of Plant Molecular Pathology, The Nambu University, Advanced Jungang-ro 23 street (Wolgye-dong 864-1), Gwangsan gu, Gwangju 506-706, Korea.
authors.forename: Youngjin
authors.initials: Y
authors.lastname: Lee
keywords: ABC transporter gene; Lysimachia foenum-graecum Herba; Magnaporthe oryzae; biopesticide; blasticidin S; fungicide resistance; plant extract; rice blast disease