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MicroRNA knockdown contributes to compromised SAR in potato and
tobacco indicating novel functions of miRNA160 and miRNA166
Bhavani N1, Godbole P1, Kalsi H.S1, Supreeth K.S1, Siddappa S2, Singh B.P2, Aarthy T3,
Thulasiram H.V3 and A. K. Banerjee1*
1.
Indian Institute of Science Education and Research (IISER Pune), Dr. Homi Bhabha
Road, Pune, India – 411008
2 Central
3.
Potato Research Institute (CPRI), Shimla, India – 171001
National Chemical Laboratory (NCL), Dr. Homi Bhabha Road, Pune, India – 411008
* Corresponding author: [email protected]
Systemic Acquired Resistance (SAR) is a broad spectrum disease resistance mounted
in non-infected plant parts upon a local infection. Previous studies have explored SAR with
respect to mRNAs, proteins, peptides, small molecules and hormones; however, microRNAs
mediated control of SAR has not been investigated yet. We have undertaken a target mimicry
based knockdown approach to understand the role of microRNAs 160 and 166 (miR160 and
miR166) in the process of SAR establishment during Phytophthora infestans infection in
potato and tobacco. We demonstrate that in wild-type potato plants, levels of both these
microRNAs and their targets are altered at local and systemic leaves upon P. infestans
infection at different time points; however, their levels remain unaffected in phloem sap
RNA. Mimicry lines of MIM160, MIM166, eTM160 and eTM166 of both potato and tobacco
exhibited increased susceptibility to P. infestans compared to wild-type plants correlating
with reduced levels of PR1 as analyzed by qRT-PCR. A compromised SAR was observed
when these lines were subjected to P. infestans infection followed by Ralstonia
solanacearum treatment. Interestingly, we have detected low levels of SABP2 mRNA in
these mimicry lines. We hypothesize that this low level of SABP2 might have affected the
conversion of MeSA to SA and have resulted in a compromised SAR. To test this hypothesis,
bio-chemical analyses as well as grafting studies are being conducted. Overall, our study
demonstrates that miR160 and miR166 play a dynamic role in modulating SAR in potato and
tobacco during P. infestans infection.