Hemibiotrophic Phytophthora infestans Modulates the Expression of SWEET Genes in Potato (Solanum tuberosum L.)
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Date
2023-09
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Abstract
Sugar Efflux transporters (SWEET) are involved in diverse biological processes of plants.
Pathogens have exploited them for nutritional gain and subsequently promote disease progression.
Recent studies have implied the involvement of potato SWEET genes in the most devastating late blight
disease caused by Phytophthora infestans. Here, we identified and designated 37 putative SWEET genes
as StSWEET in potato. We performed detailed in silico analysis, including gene structure, conserved
domains, and phylogenetic relationship. Publicly available RNA-seq data was harnessed to retrieve
the expression profiles of SWEET genes. The late blight-responsive SWEET genes were identified from
the RNA-seq data and then validated using quantitative real-time PCR. The SWEET gene expression
was studied along with the biotrophic (SNE1) and necrotrophic (PiNPP1) marker genes of P. infestans.
Furthermore, we explored the co-localization of P. infestans resistance loci and SWEET genes. The
results indicated that nine transporter genes were responsive to the P. infestans in potato. Among
these, six transporters, namely StSWEET10, 12, 18, 27, 29, and 31, showed increased expression after
P. infestans inoculation. Interestingly, the observed expression levels aligned with the life cycle of P.
infestans, wherein expression of these genes remained upregulated during the biotrophic phase and
decreased later on. In contrast, StSWEET13, 14, and 32 didn’t show upregulation in inoculated samples
suggesting non-targeting by pathogens. This study underscores these transporters as prime P. infestans
targets in potato late blight, pivotal in disease progression, and potential candidates for engineering
blight-resistant potato genotypes.