The Cysteine-Rich Peptide Snakin-2 Negatively Regulates Tubers Sprouting through Modulating Lignin Biosynthesis and H2O2 Accumulation in Potato

Abstract

Potato tuber dormancy is critical for the post-harvest quality. Snakin/Gibberellic Acid Stimulated in Arabidopsis (GASA) family genes are involved in the plants’ defense against pathogens and in growth and development, but the effect of Snakin-2 (SN2) on tuber dormancy and sprouting is largely unknown. In this study, a transgenic approach was applied to manipulate the expression level of SN2 in tubers, and it demonstrated that StSN2 significantly controlled tuber sprouting, and silencing StSN2 resulted in a release of dormancy and overexpressing tubers showed a longer dormant period than that of the control. Further analyses revealed that the decrease expression level accelerated skin cracking and water loss. Metabolite analyses revealed that StSN2 significantly down-regulated the accumulation of lignin precursors in the periderm, and the change of lignin content was documented, a finding which was consistent with the precursors’ level. Subsequently, proteomics found that cinnamyl alcohol dehydrogenase (CAD), caffeic acid O-methyltransferase (COMT) and peroxidase (Prx), the key proteins for lignin synthesis, were significantly up-regulated in silencing lines, and gene expression and enzyme activity analyses also supported this effect. Interestingly, we found that StSN2 physically interacts with three peroxidases catalyzing the oxidation and polymerization of lignin. In addition, SN2 altered the hydrogen peroxide (H2O2) content and the activities of superoxide dismutase (SOD) and catalase (CAT). These results suggest that StSN2 negatively regulates lignin biosynthesis and H2O2 accumulation, and ultimately inhibits the sprouting of potato tubers.

Snakin-2 interacts with cytosolic glyceraldehyde-3-phosphate dehydrogenase 1 to inhibit sprout growth in potato tubers

“…Similarly, in potato, Nahirñak et al [27] reported that StSN1 could interact with StDWF1, affect the interaction of gibberellin, salicylic acid, and brassinolipids, and participate in hormone balance [ 27 ]. In our previous results, no direct interaction was observed between StSN2 and StDWF1 in a yeast two-hybrid experiment, although StSN2 could interact with three peroxidase isoforms involved in peroxidase-regulated lignin synthesis pathways in yeast cells, indicating that StSN2 negatively regulates lignin biosynthesis and hydrogen peroxide accumulation and ultimately inhibits tuber sprouting [ 12 ].…”

“…During potato storage, tuber sprouting comprises a series of perplexing physiological and biochemical processes [ 22 ]. In recent research, we found that overexpression of StSN2 inhibited tuber sprout growth, while RNAi lines showed accelerated sprout growth [ 12 ]. In the current study, the qRT–PCR results indicate that the expression of StSN2 is highest in FR (short dormancy variety) and the lowest in BS (long-dormancy variety) after harvest (0 days).…”

“…7d ). The low hydrogen peroxide content in StSN2 -OEX27 tubers [ 12 ] might result in a lower oxidative level of StGAPC1 and increased StGAPC1 nuclear accumulation. More experiments will be performed in the future to confirm this conjecture.…”

“…Our previous study showed that StSN2 displayed higher expression levels in dormancy than when sprouting [ 10 ], and this expression pattern was verified by proteome analysis [ 11 ]. Furthermore, StSN2 -overexpressing tubers exhibited slower sprout growth than RNA interference (RNAi) tubers and altered hydrogen peroxide content, superoxide dismutase, and catalase activities [ 12 ]. However, the molecular mechanism by which StSN2 inhibits sprout growth is still unclear.…”

Screening and identification of potato StSPS1, a potential crucial gene regulating seed potato vigor

“…The speci c information of the primers is shown in Table 1. The expression data of StSPS family members in the transcriptome and proteome came from our previous research (Li L Q et al 2017;Deng et al 2021). The tissue expression data used for comparison and analysis came from Ensembl Plants (http://plants.ensembl.org/index.html), and the bud eye tissue in this study corresponds to the tuber cortex tissue in the database.…”