Steroidal glycoalkaloids (SGAs), predominantly comprising α-solanine (CHNO) and α-chaconine (CHNO), function as natural phytotoxins within potatoes. In addition to their other roles, these SGAs are crucial for enabling potato plants to withstand biotic stresses. However, they also exhibit toxicity towards humans and animals. Consequently, the content and distribution of SGAs are crucial traits for the genetic improvement of potatoes. This review focuses on advancing research related to the biochemical properties, biosynthesis, regulatory mechanisms, and genetic improvement of potato SGAs. Furthermore, we provide perspectives on future research directions to further enhance our understanding of SGA biosynthesis and regulation, ultimately facilitating the targeted development of superior potato varieties.

4-α-glucanotransferase (EC 2.4.1.25) mediated glucan transfer in starch provides opportunities for production of clean label starch ingredients with unique gelling properties. 4-α-glucanotransferases can be found in glycoside hydrolase (GH) family GH13, GH57, and in the monospecific glycoside hydrolase family 77 (GH77). Here, pH-temperature optima, steady-state kinetics, potato starch modifying properties and structural folds are reported for six phylogenetically distinct GH77 members, representing four different domain architectures including a novel multi-domain 4-α-glucanotransferase from Lactococcus lactis. Four of the enzymes exhibited starch modifying activity leading to a gradual decrease of the amylose content, elongation of amylopectin chains, and enabled formation of firm starch gels. Unexpectedly, these diverse enzymes catalyzed similar changes in chain length distributions. However, the amylose depletion and amylopectin elongation rates spanned more than two orders of magnitude between the enzyme showing very different specific activities. Tt4αGT from Thermus thermophilus had highest temperature optimum (73 °C) and superior potato starch modifying efficacy compared to the other five enzymes.

Invertases are ubiquitous enzymes that irreversibly cleave sucrose into fructose and glucose. Plant invertases play important roles in carbohydrate metabolism, plant development, and biotic and abiotic stress responses. In potato (Solanum tuberosum), invertases are involved in 'cold-induced sweetening' of tubers, an adaptive response to cold stress, which negatively affects the quality of potato chips and French fries. Linkage and association studies have identified quantitative trait loci (QTL) for tuber sugar content and chip quality that colocalize with three independent potato invertase loci, which together encode five invertase genes. The role of natural allelic variation of these genes in controlling the variation of tuber sugar content in different genotypes is unknown.

Soil-incorporated rotation/green manure crops were evaluated for management of potato early dying caused by Verticillium dahliae and Pratylenchus penetrans. After two years of rotation/green manure and a subsequent potato crop, P. penetrans numbers were less after 'Saia' oat/'Polynema' marigold, 'Triple S' sorghum-sudangrass, or 'Garry' oat than 'Superior' potato or 'Humus' rapeseed. The area under the disease progress curve (AUDPC) for early dying was lowest after Saia oat/marigold, and tuber yields were greater than continuous potato after all crops except sorghum-sudangrass. Saia oat/marigold crops resulted in the greatest tuber yields. After one year of rotation/green manure, a marigold crop increased tuber yields and reduced AUDPC and P. penetrans. In the second potato crop after a single year of rotation, plots previously planted to marigolds had reduced P. penetrans densities and AUDPC and increased tuber yield. Rapeseed supported more P. penetrans than potato, but had greater yields. After two years of rotation/green manure crops and a subsequent potato crop, continuous potato had the highest AUDPC and lowest tuber weight. Rotation with Saia oats (2 yr) and Rudbeckia hirta (1 yr) reduced P. penetrans and increased tuber yields. AUDPC was lowest after R. hirta. Two years of sorghum-sudangrass did not affect P. penetrans, tuber yield or AUDPC. These results demonstrate that P. penetrans may be reduced by one or two years of rotation to non-host or antagonistic plants such as Saia oat, Polynema marigold, or R. hirta and that nematode control may reduce the severity of potato early dying.

The plastid ribosomal protein s16 (rps16) gene was cloned from potato (Solanum tuberosum L. ssp. tuberosum cv Desiree) by PCR amplification to obtain a new homologous recombination site of plastid transformation. The potato rps16 genomic clone was 1627 bp in size and the coding region was interrupted by an 859 bp intron. Exon I was 40 bp, encoding 13 amino acids and exon II was 227 bp, encoding a 76 amino acid polypeptide. The nucleotide sequence of the rps16 gene from the "Désirée" potato shared perfect identity with the sequence from the "Superior" potato in the coding region. Three nucleotide substitutions, two nucleotide insertions, and one nucleotide deletion were found between the intron sequence of both "Désirée" and "Superior" cultivars. The amino acid sequence of the potato rps16 gene showed a high level of identity with rice, maize, tobacco, and mustard (84-94%) and a relatively low level compared with Bacillus stearothermophilus and E. coli (27-28%). Expression of the rps16 gene was strong in chloroplasts and transcripts were detectable in amyloplasts, suggesting that the rps16 gene is active in nonphotosynthetic plastids as well as in photosynthetic plastids. These results indicate that the potato rps16 gene can be used as a new homologous recombination site of plastid transformation for potato cultivars.

Seventy-three Ohio fields comprising ca. 440 ha of cv Superior potatoes were surveyed in 1977 for plant-parasitic nematodes. Of eight genera of plant-parasitic nematodes, Pratylenchus was found most frequently, occurring in 65% of the soil samples and 84% of the root samples. Populations of Pratylenchus were consistently higher than populations of the other nematode genera. The six species of Pratylenchus extracted from potato roots, in descending order of frequency, were P. crenatus, P. penetrans, P. scribneri, P. alleni, P. thornei, and P. neglectus. Prevalence of these Pratylenchus species in Ohio potato fields suggests that they could be involved with vascular wilt fungi in premature death of cv Superior potato vines known in Ohio as "early dying."