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Growth-regulating factors (GRFs) are transcription factors that play a pivotal role in plant growth and development. This study identifies 12 Solanum tuberosum GRF transcription factors (StGRFs) and analyzes their physicochemical properties, phylogenetic relationships, gene structures and gene expression patterns using bioinformatics. The StGRFs exhibit a length range of 266 to 599 amino acids, with a molecular weight of 26.02 to 64.52 kDa. The majority of StGRFs possess three introns. The promoter regions contain a plethora of cis -acting elements related to plant growth and development, as well as environmental stress and hormone response. All the members of the StGRF family contain conserved WRC and QLQ domains, with the sequences of these two conserved domain modules exhibiting high levels of conservation. Transcriptomic data indicates that StGRFs play a significant role in the growth and development of stamens, roots, young tubers, and other tissues or organs in potatoes. Furthermore, a few StGRFs exhibit differential expression patterns in response to Phytophthora infestans , chemical elicitors, heat, salt, and drought stresses, as well as multiple hormone treatments. The results of the expression analysis indicate that StGRF1 , StGRF2 , StGRF5 , StGRF7 , StGRF10 and StGRF12 are involved in the process of tuber sprouting, while StGRF4 and StGRF9 may play a role in tuber dormancy. These findings offer valuable insights that can be used to investigate the roles of StGRFs during potato tuber dormancy and sprouting.

Potato is an important food crop. After harvest, these tubers will undergo a period of dormancy. Brassinosteroids (BRs) are a new class of plant hormones that regulate plant growth and seed germination. In this study, 500 nM of BR was able to break the dormancy of tubers. Additionally, exogenous BR also upregulated BR signal transduction genes, except for StBIN2. StBIN2 is a negative regulator of BR, but its specific role in tuber dormancy remains unclear. Transgenic methods were used to regulate the expression level of StBIN2 in tubers. It was demonstrated that the overexpression of StBIN2 significantly prolonged tuber dormancy while silencing StBIN2 led to premature sprouting. To further investigate the effect of StBIN2 on tuber dormancy, RNA-Seq was used to analyze the differentially expressed genes in OE-StBIN2, RNAi-StBIN2, and WT tubers. The results showed that StBIN2 upregulated the expression of ABA signal transduction genes but inhibited the expression of lignin synthesis key genes. Meanwhile, it was also found that StBIN2 physically interacted with StSnRK2.2 and StCCJ9. These results indicate that StBIN2 maintains tuber dormancy by mediating ABA signal transduction and lignin synthesis. The findings of this study will help us better understand the molecular mechanisms underlying potato tuber dormancy and provide theoretical support for the development of new varieties using related genes.

In plants, nitric oxide synthase (NOS)-like or nitrate reductase (NR) produces nitric oxide (NO), which is involved in releasing seed dormancy. However, its mechanism of effect in potato remains unclear. In this study, spraying 40 μM sodium nitroprusside (SNP), an exogenous NO donor, quickly broke tuber dormancy and efficiently promoted tuber sprouting, whereas 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO), an NO scavenger, repressed the influence of NO on tuber sprouting. Compared with the control (distilled water), SNP treatment led to a rapid increase in NO content after 6 h and a decreased abscisic acid (ABA) content at 12 and 24 h. c-PTIO treatment significantly inhibited increase of NO levels and increased ABA production. In addition, N -nitro-L-arginine methyl ester, an NOS inhibitor, clearly inhibited the NOS-like activity, whereas tungstate, an NR inhibitor, inhibited the NR activity. Furthermore, NO promoted the expression of a gene involved in ABA catabolism ( , encoding ABA 8'-hydroxylase) and inhibited the expression of a gene involved in ABA biosynthesis ( , encoding 9- -epoxycarotenoid dioxygenase), thereby decreasing the ABA content, disrupting the balance between ABA and gibberellin acid (GA), and ultimately inducing dormancy release and tuber sprouting. The results demonstrated that NOS-like or NR-generated NO controlled potato tuber dormancy release and sprouting via ABA metabolism and signaling in tuber buds.

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.

The time of application of gibberellic acid on potato tuber growth and physiological ageing was studied. Potato plants derived from botanical seed were sprayed at five stages during their growth cycle, and tubers were harvested at 10-day intervals after treatment. It was found that hybrid Chacasina F 1 forms tubers until approximately 50 days after transplantation irrespective of the season (spring or autumn). Foliar sprays with gibberellic acid 30–50 days after transplantation suppressed the growth of pre-formed tubers for about 10 days after application and promoted the induction of new tubers, leading to a higher number of tubers per plant in comparison with the untreated control. This temporary effect of gibberellic acid resulted in a reduction in mean tuber weight, but generally without affecting the total weight (yield) of tubers per plant. In addition, gibberellic acid affected the physiological age of the tubers by inducing the breakage of bud dormancy at all stages of tuber growth. Overall, at all harvest times except 90DAT, earlier sprouting and/or a higher number of sprouted buds per tuber were observed for the treatments in which GA was applied within 20 days of harvest.

Dormancy hinders progress in attempts to fast track potato tuber generations. In this study, we evaluated the ability of gibberellic acid (GA) to overcome dormancy in freshly harvested tubers of eleven potato cultivars in two years of field trials. Tubers were wounded and dipped in 0, 10, 100, and 1000 ppm GA. Then, they were planted in the field five days later. Vine length and stem number were measured throughout the season. Tubers were also harvested and weighed. Cultivars varied in their response to GA treatment. However, for all cultivars, wounding followed by treatment with 10 or 100 ppm effectively overcame dormancy. The 1000 ppm treatment produced excessive vine growth and lower yield compared to the lower concentrations. Consequently, wounding of freshly harvested tubers, followed by a dip in 10 ppm GA is recommended to overcome tuber dormancy in programs interested in rapid cycling.

Identification of molecular markers defining the end of tuber dormancy prior to visible sprouting is of agronomic interest for potato growers and the potato processing industry. In potato tubers, breakage of dormancy is associated with the reactivation of meristem function. In dormant meristems, cells are arrested in the G₁/G₀ phase of the cell cycle and re-entry into the G₁ phase followed by DNA replication during the S phase enables bud outgrowth. Deoxyuridine triphosphatase (dUTPase) is essential for DNA replication and was therefore tested as a potential marker for meristem reactivation in tuber buds. The corresponding cDNA clone was isolated from potato by PCR. The deduced amino acid sequence showed 94% similarity to the tomato homologue. By employing different potato cultivars, a positive correlation between dUTPase expression and onset of tuber sprouting could be confirmed. Moreover, gene expression analysis of tuber buds during storage time revealed an up-regulation of the dUTPase 1 week before visible sprouting occurred. Further analysis using an in vitro sprout assay supported the assumption that dUTPase is a good molecular marker to define the transition from dormant to active potato tuber meristems.

Tuber morphology and propagation efficiency in three dioecious, tuber bearing Momordica species of India were investigated. Tuber morphology of M. dioica and M. sahyadrica is different from that of M. subangulata ssp. renigera. M. dioica and M. sahyadrica develop taproot tuber with shoot sprouts only at caudex region, whereas M. subangulata ssp. renigera has both taproot and adventitious tubers with shoot sprouts all over tuber surface. Tubers of M. dioica and M. sahyadrica are perennating whereas, in M. subangulata ssp. renigera they serve as both perennating and propagation structures. M. dioica and M. sahyadrica had prolonged tuber dormancy of 4-5 months whereas, M. subangulata ssp. renigera had short dormancy period of about 2 months. Cutting of tuberous roots is a highly efficient method for multiplication in M. subangulata spp. renigera, whereas whole tubers or longitudinal splits in to two or at best four equal halves with a portion of the apical meristem may work in the case of M. dioica and M. sahyadrica.

Alpine Russet is a later maturing, oblong-long, lightly russeted potato cultivar, notable for having tuber dormancy comparable to Russet Burbank. Processing quality of Alpine Russet from long-term storage is superior to Russet Burbank, with low percent reducing sugars and uniform fry color due to a low percentage difference of sugars between the bud and stem ends. Alpine Russet yields were comparable to Russet Burbank in early harvest trials and were comparable or significantly larger in late harvest trials depending on the location. At two late season locations, Alpine Russet had the largest total and percent No. 1 yields and the largest percent mid-range No. 1 tubers compared to Ranger Russet and Russet Burbank. It has moderately high specific gravity and is resistant to most external and internal defects. Alpine Russet has been evaluated in public and industry trials throughout the Western U.S. for over 15 years.