Molecular characterization of emaraviruses associated with Pigeonpea sterility mosaic disease

Area of Science:

• Plant Virology
• Molecular Biology
• Agricultural Science

Background:

• Sterility Mosaic Disease (SMD) in pigeonpea is a significant agricultural challenge.
• The disease is often caused by mixed infections of viruses, complicating diagnosis.
• Pigeonpea sterility mosaic virus-I (PPSMV-I) and Pigeonpea sterility mosaic virus-II (PPSMV-II) are implicated in SMD.

Purpose of the Study:

• To characterize the viral agents causing Sterility Mosaic Disease in pigeonpea.
• To differentiate between Pigeonpea sterility mosaic virus-I and II using molecular and serological methods.
• To elucidate the molecular mechanisms of viral transcription and movement.

Main Methods:

• Deep sequencing of small RNA (sRNA) and dsRNA profiling from infected pigeonpea samples.
• Comparative genomic analysis of PPSMV-I and PPSMV-II.
• Standardization of Enzyme-Linked Immunosorbent Assay (ELISA) for virus detection.
• Mite inoculation experiments.

Main Results:

• PPSMV-I and PPSMV-II were identified in pigeonpea samples from different locations.
• PPSMV-I genome comprises four RNAs, while PPSMV-II has six RNAs.
• PPSMV-II shows greater relatedness to Fig mosaic virus (FMV) than to PPSMV-I.
• A specific ELISA method was developed for distinguishing between PPSMV-I and PPSMV-II.
• The RNA-dependent RNA polymerase (RdRp) contains a 'cap-snatching' endonuclease domain, and P4 functions as the movement protein.

Conclusions:

• The study provides a comprehensive characterization of PPSMV-I and PPSMV-II, the causal agents of pigeonpea sterility mosaic disease.
• A reliable diagnostic tool (ELISA) was developed for differentiating these two viruses.
• Key viral proteins involved in transcription and cell-to-cell movement were identified, offering insights into viral pathogenesis.