Evaluation of a SUMO E2 Conjugating Enzyme Involved in Resistance to Clavibacter michiganensis Subsp. michiganensis in Solanum peruvianum, Through a Tomato Mottle Virus VIGS Assay

Abstract

Clavibacter michiganensis subsp. michiganensis (Cmm) causes bacterial wilt and canker of tomato. Currently, no Solanum lycopersicum resistant varieties are commercially available, but some degree of Cmm resistance has been identified in Solanum peruvianum. Previous research showed up-regulation of a SUMO E2 conjugating enzyme (SCEI) transcript in S. peruvianum compared to S. lycopersicum following infection with Cmm. In order to test the role of SCEI in resistance to Cmm, a fragment of SCEI from S. peruvianum was cloned into a novel virus-induced gene-silencing (VIGS) vector based on the geminivirus, Tomato Mottle Virus (ToMoV). Using biolistic inoculation, the ToMoV-based VIGS vector was shown to be effective in S. peruvianum by silencing the magnesium chelatase gene, resulting in leaf bleaching. VIGS with the ToMoV_SCEI construct resulted in ~61% silencing of SCEI in leaves of S. peruvianum as determined by quantitative RT-PCR. The SCEI-silenced plants showed unilateral wilting (15 dpi) and subsequent death (20 dpi) of the entire plant after Cmm inoculation, whereas the empty vector-treated plants only showed wilting in the Cmm-inoculated leaf. The SCEI-silenced plants showed higher Cmm colonization and an average of 4.5 times more damaged tissue compared to the empty vector control plants. SCEI appears to play an important role in the innate immunity of S. peruvianum against Cmm, perhaps through the regulation of transcription factors, leading to expression of proteins involved in salicylic acid-dependent defense responses.

Phloem-Triggered Virus-Induced Gene Silencing Using a Recombinant Polerovirus

“…It is noteworthy that the silencing efficiency for the phloem-specific RTM1 gene using Tu- RTM1 reached nearly 90%, highlighting the robustness and the usefulness of TuYV vectors. For a non-phloem specific gene ( CHLI1 ) the knockdown level obtained with the phloem-specific TuYV vector is in the same range (49–67%) as those obtained with several non-phloem specific VIGS systems (70% for a Potato virus X vector ( Ratcliff et al, 2001 ), 61–87% for TMV-based vectors ( Lacomme et al, 2003 ), 75–90% for TYMV-PDS ( Pflieger et al, 2008 ), 61% for a geminivirus Tomato mottle virus- chI I ( Esparza-Araiza et al, 2015 ) and 40–80% for a pararetrovirus Rice tungro baciliform virus- chl H ( Kant and Dasgupta, 2017 ). The paradoxical important reduction of non-phloem CHLI1 transcripts in plants infected with phloem-limited TuYV recombinants can be explained by the spread of the vsiRNAs, produced in infected phloem cells, into the surrounding cells, allowing the silencing process to extend beyond the sites of initiation, if not countered by the RSS P0 (see below).…”

The Maize Class-I SUMO Conjugating Enzyme ZmSCE1d Is Involved in Drought Stress Response

“…In tomato, the SCE1-silenced plants were more susceptible to a bacterial disease caused by Clavibacter michiganensis subsp. michiganensis [47]. These findings indicate that sumoylation plays a protective role in stress responses of plants.…”

Advances in the Characterization of the Mechanism Underlying Bacterial Canker Development and Tomato Plant Resistance

“…A recent study confirmed that the expression levels of the genes involved in the PAL pathway are upregulated in response to Cm infection [56]. Additionally, the silencing of the gene encoding SUMO E2-conjugating enzyme (SCEI) in plants leads to enhanced Cm colonization and a substantial increase in damaged tissues (4.5 times on average), reflecting the importance of SCEI for the innate immunity of S. peruvianum accession LA2172 [65].…”