Changes in Structural and Thermodynamic Properties of Starch during Potato Tuber Dormancy

Abstract

The main reserve polysaccharide of plants—starch—is undoubtedly important for humans. One of the main sources of starch is the potato tuber, which is able to preserve starch for a long time during the so-called dormancy period. However, accumulated data show that this dormancy is only relative, which raises the question of the possibility of some kind of starch restructuring during dormancy periods. Here, the effect of long-term periods of tuber rest (at 2–4 °C) on main parameters of starches of potato tubers grown in vivo or in vitro were studied. Along with non-transgenic potatoes, Arabidopsis phytochrome B (AtPHYB) transformants were investigated. Distinct changes in starch micro and macro structures—an increase in proportion of amorphous lamellae and of large-sized and irregular-shaped granules, as well as shifts in thickness of the crystalline lamellae—were detected. The degree of such alterations, more pronounced in AtPHYB-transgenic tubers, increased with the longevity of tuber dormancy. By contrast, the polymorphic crystalline structure (B-type) of starch remained unchanged regardless of dormancy duration. Collectively, our data support the hypothesis that potato starch remains metabolically and structurally labile during the entire tuber life including the dormancy period. The revealed starch remodeling may be considered a process of tuber preadaptation to the upcoming sprouting stage.

Molecular Insights into the Accelerated Sprouting of and Apical Dominance Release in Potato Tubers Subjected to Post-Harvest Heat Stress

“…The downregulated gene set was enriched with starch metabolism, photomorphogenesis, and Circadian Rhythm-Plant pathways. Previous research has substantiated the pivotal role of starch metabolism in regulating potato sprouting [15], illustrating that the concurrent suppression of isoamylases ISA1, ISA2, and ISA3 can accelerate sprouting [16], whereas inhibiting α-amylase StAmy23 tends to delay sprouting [17]. Photomorphogenesis and Circadian Rhythm-Plant pathways play a crucial role in regulating plant development.…”

Advances in the Modulation of Potato Tuber Dormancy and Sprouting

“…Throughout the dormancy period, the starch in potato tubers remains metabolically and structurally unstable, suggesting that tubers undergo ongoing biochemical and physical changes despite their dormant state. Studies have shown that the average size of starch grains in stored potato tubers increases, with a concomitant decline in the frequency of smaller grains [53]. This observation suggests that starch granules, especially the smaller ones, may undergo a fusion process during tuber dormancy.…”

“…Thus, dormancy appears to be associated with an increase in structural defects within the starch matrix. The storage stage not only alters the starch's crystalline structure but also leads to the proliferation of these defects [53]. Notably, the melting of starch at lower temperatures suggests the dissolution of more defective crystalline lamellae relative to those that melt at elevated temperatures.…”