Physiological and Molecular Mechanisms Associated with Potato Tuber Dormancy

Tuber dormancy is an important physiological trait that impacts postharvest storage and end use qualities of potatoes. Overall, dormancy regulation of potato tuber is a complex process driven by genetic as well as environmental factors. Elucidation of the molecular and physiological mechanisms that influence different dormancy stages of tuber has wider potato breeding and industry relevant implications. Therefore, the primary objective of this review is to present the current knowledge on the diversity in tuber dormancy traits among wild relatives of potatoes and discuss how genetic and epigenetic factors contribute to the tuber dormancy. Advancements in understanding of key physiological mechanisms involved in tuber dormancy regulations, such as apical dominance, phytohormone metabolism, and oxidative stress responses were also discussed. This review highlights the impacts of common sprout suppressors on the molecular and physiological mechanisms associated with tuber dormancy and other storage qualities. Collectively, the literature suggests that significant changes in expressions of genes associated with cell cycle, phytohormone metabolism, and oxidative stress response influence initiation, maintenance, and termination of dormancy in potato tubers. Commercial sprout suppressors mainly alter the expressions of genes associated with cell cycle and stress responses and suppress sprout growth rather than prolonging the tuber dormancy.

Congenital hypertrophy of retinal pigment epithelium (CHRPE) as a marker for familial adenomatous polyposis (FAP)

Seventy-eight patients from 26 families were examined to evaluate the potentiality of congenital hypertrophy of retinal pigment epithelium (CHRPE) as a phenotypic marker for familial adenomatous polyposis (FAP). The examined subjects were divided into three different groups: Group I, patients with FAP without extra colonic manifestations (ECM); Group II, patients with FAP and ECM (desmoids/osteomas/upper gastrointestinal adenomas); and Group III, individuals at risk without FAP. Of 24 Group I patients (median age 18 years) 16 had CHRPE compared with 14 out of 24 patients (median age 29 years) in Group II and only three out of 30 patients in Group III. The overall sensitivity of CHRPE for FAP was 70% (+/- 13%) without any difference related to ECM; the predictive value was 92%. The specificity calculated from Group III (median age 26 years) was 90%, but the results should not be considered as definitive because a longer follow-up to determine the appearance of adenomas is required. The data suggest that examination for CHRPE is an inexpensive, non-invasive test for FAP, but the absence of retinal lesions does not eliminate the necessity for adequate follow-up of individuals at risk.