4.3 Trehalose treatment affects PpINH1, leading to improved cold
resistance in peaches
In most plants, the amount of endogenous trehalose is typically low,
however, it is strongly induced by environmental stresses, including
extreme temperatures, salinity, and drought. Therefore, endogenous
trehalose may be involved not only in plant metabolism, but also in
signaling pathways (Paul et al. 2008). Application of exogenous
trehalose may induce plant signal molecules that modulate the expression
of stress response genes, thereby improving crops’ resistance to
stresses (Kosar et al. 2019). Kosar et al. (2019) have reported that the
application of exogenous trehalose improves the cold resistance of crops
and harvested fruits, and Ding & Wang (2018) report that 10% trehalose
treatment enhances the cold tolerance of fresh-cut pepper fruits by
enhancing antioxidant activity and reducing cell ultrastructure injury.
The mechanisms of these affects however, have not yet been reported. In
this study, application of 1% trehalose to peaches in cold storage
resulted in significantly enhanced PpINH1 expression, reduced VIN
activity, and higher sucrose content, ultimately alleviating CI symptoms
(Figure 6 ). These results suggest that up-regulated INHs
inhibit VIN activity at the post-translational level in peach fruit.
Like overexpression of PpINH1 inhibiting the VIN in peaches
(Figure 4 ), overexpression of StInvInh2A andStInvInh2B inhibits StvacINV1 in stored tubers, alleviating
cold-induced sweetening and the resulting deterioration of quality (Liu
et al., 2013). Similarly, when RNAi technology was used to silence the
expression of the soybean invertase inhibitor GmCIF1 in transgenic
plants, CWI activity increased significantly. These results suggest that
VIN activity may be negatively regulated by INHs in plants (Tang et al.,
2017).
Based on our findings we suggest that upregulated the expression ofPpINH1 results in the decreased VIN activity, increased sucrose
content, and ultimately enhanced chilling resistance (Figure
7 ). This provides insight into the mechanism of enhancing chilling
resistance by trehalose treatment.