Putative Role of a Yet Uncharacterized Protein Elicitor PeBb1 Derived from Beauveria bassiana ARSEF 2860 Strain against Myzus persicae (Homoptera: Aphididae) in Brassica rapa ssp. pekinensis.

Talha Nazir,Iqra Nawaz,Abdul Basit,Muhammad Zeeshan Majeed,Dewen Qiu,Tauqir Anwar,Abdul Hanan

doi:10.3390/pathogens9020111

Abstract

This study reports the characterization of protein elicitor PeBb1 derived from entomopathogenic fungus Beauveria bassiana ARSEF-2860 strain and its putative role in induced systemic resistance in Brassica rapa ssp. pekinensis against green peach aphid Myzus persicae. The sequence of purified elicitor protein was matched with the genomic sequence of a hypothetical protein BBA_10269 from B. bassiana ARSEF-2860 (GenBank Accession No. XP_008603588.1). The protein-encoding gene PeBb1 contained 534 bp cDNA encoding a polypeptide of 177 amino acids with a molecular mass of 19 kDa. The recombinant elicitor protein was expressed in Escherichia coli using pET-28a (+) expression vector and induced necrosis in the leaves of tobacco. The effects of elicitor protein on aphid M. persicae was determined by applying three different concentrations of PeBb1 (i.e., 26, 35, 53 μM) on B. rapa plants at 4-leaf stage and the treated plants were exposed to newly emerged (0–6 h old) apterous adult aphids. Bioassay results showed significant (p < 0.05) sub-lethal effects of the exogenous application of PeBb1 elicitor on M. persicae. Moreover, the RT-qPCR gene expression analyses showed a significant up-regulation of most of the key genes linked to ethylene (ET)- and jasmonic acid (JA)-associated plant defense pathways in elicitor-treated plants. These results not only recommend the putative utilization of PeBb1 elicitor protein in future biological pest control strategies against phloem-feeding insect pests such as M. persicae, but also help in better comprehension of the mechanisms through which beneficial fungi trigger the induced plant resistance.

Highlights

Phytophagous insect pests are one of the major threats to agricultural production across the globe
To clarify one of the putative modes of PeBb1 action resulting in plant resistance, we evaluated the expression profiles of ET and jasmonic acid (JA) pathway related marker genes inducing plant defense mechanisms against aphids up to 48 h after treatment with PeBb1 (53 μM) or buffer
This study reports the purification, characterization, and evaluation of a yet uncharacterized protein elicitor PeBb1 from B. bassiana strain ARSEF 2860 as putative microbial pest control tool against green peach aphid M. persicae

Summary

Introduction

Phytophagous insect pests are one of the major threats to agricultural production across the globe. These pests are estimated to cause more than 15% loss to global crop production annually [1,2]. Many microbes including entomopathogenic fungi, bacteria, viruses, and nematodes have shown effectiveness against a large number of insect pest species [6,7]. With more than 750 species worldwide, entomopathogenic fungi provide a promising potential for biological control of insect pests. Fungal species belonging to genera Beauveria, Isaria, Lecanicillium, and Metarhizium exhibit an excellent pathogenicity against many insect pests [8,9,10]

Methods

Results

Discussion

Conclusion