Chloroplast-Expressed MSI-99 in Tobacco Improves Disease Resistance and Displays Inhibitory Effect against Rice Blast Fungus

Abstract

Rice blast is a major destructive fungal disease that poses a serious threat to rice production and the improvement of blast resistance is critical to rice breeding. The antimicrobial peptide MSI-99 has been suggested as an antimicrobial peptide conferring resistance to bacterial and fungal diseases. Here, a vector harboring the MSI-99 gene was constructed and introduced into the tobacco chloroplast genome via particle bombardment. Transformed plants were obtained and verified to be homoplastomic by PCR and Southern hybridization. In planta assays demonstrated that the transgenic tobacco plants displayed an enhanced resistance to the fungal disease. The evaluation of the antimicrobial activity revealed that the crude protein extracts from the transgenic plants manifested an antimicrobial activity against E. coli, even after incubation at 120 °C for 20 min, indicating significant heat stability of MSI-99. More importantly, the MSI-99-containing protein extracts were firstly proved in vitro and in vivo to display significant suppressive effects on two rice blast isolates. These findings provide a strong basis for the development of new biopesticides to combat rice blast.

Chloroplasts: state of research and practical applications of plastome sequencing

“…tabaci bacteria (DeGray et al 2001 ). Recent research also shows that MSI-99 expressed by tobacco chloroplasts is capable of suppressing the effects of rice blast, one of the most dangerous fungal rice diseases (Wang et al 2015 ).…”

Stable Expression of Basic Fibroblast Growth Factor in Chloroplasts of Tobacco

“…Tobacco chloroplast transformation was carried out according to the protocol previously described [ 40 ]. Briefly, young leaves of in vitro cultured tobacco plants were bombarded using PDS 1000/He biolistic particle delivery system (Bio-Rad, Hercules, CA, USA) with 50 mg of 0.6 µm gold particles coated with 10 µg of plasmid DNA at 1100 psi.…”

Enhanced tolerance to Phytophthora root and stem rot by over-expression of the plant antimicrobial peptide CaAMP1 gene in soybean

“…AMPs are known to play important roles in constitutive or induced resistance to various pathogens, by degrading fungal cell walls, inducing membrane channel and pore formation, inhibiting DNA synthesis and cell cycle, and damaging cellular ribosomes [3−7]. Plant AMPs have been shown to enhance tolerance to many fungal diseases in several species, including pepper [8], rice [7,9,10], potato [11], tobacco [3], and creeping bentgrass and citrus [12,13]. In addition, a defensin from chickpea, which is a type of AMP, confers tolerance against water de cit stress in Arabidopsis thaliana [14].…”

“…cubense [7,9]. Protein extracts with MSI-99, an AMP expressed in chloroplasts of tobacco, could signi cantly suppress two rice blast isolates, both in vitro and in vivo [10]. Furthermore, leaf extracts from transplastomic tobacco were shown to inhibit the growth of pregerminated spores of three fungal species, Aspergillus avus, F. moniliforme, and Verticillium dahliae [3], whereas expression of the AMP alfAFP in transgenic greenhouse-grown potato conferred tolerance against V. dahliae, an agronomically important fungal pathogen [11].…”