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United States Department of Agriculture

Agricultural Research Service

Research Project: IDENTIFICATION AND MANIPULATION OF POSTHARVEST PHYSIOLOGICAL AND MOLECULAR PROCESSES CONTROLLING POTATO NUTRITIONAL AND MARKET QUALITY

Location: Sugarbeet and Potato Research

Title: Molecular and Cytological aspects of native periderm maturation in potato (Solanum tuberosum L.) tubers

Authors
item Neubauer, Jonathan
item Lulai, Edward
item Thompson, Asunta -
item Suttle, Jeffrey
item Bolton, Melvin
item Campbell, Larry

Submitted to: Journal of Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 31, 2012
Publication Date: March 1, 2013
Citation: Neubauer, J., Lulai, E.C., Thompson, A.L., Suttle, J.C., Bolton, M.D., Campbell, L.G. 2013. Molecular and Cytological aspects of native periderm maturation in potato tubers. Journal of Plant Physiology. 170:413-423.

Interpretive Summary: Potato (Solanum tuberosum L.) tubers are frequently damaged during harvesting and handling operations resulting in food quality loss, infections and deterioration during storage, all of which are costly to the producer, potato storage operator, grocer and consumer. The most frequent and troublesome harvest/handling damage occurs as the outer layer of the tuber periderm, i.e. the skin or phellem, is scuffed away from the tuber during harvest and handling operations. Potato tubers are susceptible to these skinning injuries during growth, but become resistant to this type of wounding as the periderm matures. This maturation generally occurs after the potato vine senesces naturally or sometime after harvest. Mature native periderm that exhibits resistance to excoriation (RE) is the primary defense for potato tubers against abiotic and biotic challenges. However, little is known about the physiology of periderm maturation or associated gene expressions that promote, mark or indicate the status of this process. In this study, native periderm maturation events and associated gene expressions were determined in coordination with the termination of native periderm development and the following onset and progression of native periderm maturation. The study was conducted using two diverse potato genotypes (NDTX4271-5R (ND), a red skinned phenotype and Russet Burbank (RB), a russeted skinned phenotype; 2008 and 2009 crops) both grown in two different crop years. The potato tubers were sampled at four harvest maturities ranging from immature to mature. Approximately 104 d after planting, the periderm of the newly formed tubers terminated production of phellem cells which constitute the tuber skin. This termination of periderm phellem cell layers production indicated cessation of cell division by the mother cells (phellogen) of the periderm. Phellogen radial cell walls, which held the skin (phellem) in place, thickened as periderm matured throughout the harvests. The thickening/strengthening of radial phellogen cell walls increased resistance to skinning injury (skin-set). In both genotypes, the cell cycle gene cyclin-dependent kinase B (StCDKB) rapidly down-regulated after the second harvest coinciding with cessation of cell division by the phellogen. Expression patterns of genes encoding epidermal growth factor binding protein (StEBP) and cyclin-dependent kinase regulatory subunit (StCKS1At) were less indicative of phellogen inactivation and periderm maturation. The expression profile for genes encoding the structural cell wall proteins extensin (StExt1) and extensin-like (StExtlk) suggested involvement with completion of phellem cell accumulation and on-set of periderm maturation. The expression of genes encoding a cell wall strengthening “tyrosine-and lysine-rich protein” (StTLRP) and pectin methyl esterase (StPME) increased in phellogen cells from later harvests of ND tubers from the 2008 crop as did StExt1 for ND 2008 and ND 2009 crops; this suggests roles in phellem cell generation and completion of delayed cell wall development in non-meristematic phellogen cells of ND, the red skinned phenotype. StCDKB and StPrePME genes were rapidly down-regulated by the third harvest for both genotypes. Collectively, these results indicate that the genes analyzed are active during native periderm formation. The decreased expression of StCDKB and StPrePME after cessation of tuber phellem/skin production coordinates with the on-set of periderm maturation and skin-set progression suggesting that these genes may have utility in technologies associated with improving or monitoring periderm maturation. The continued thickening of phellogen cell walls during periderm maturation coordinates with the development of resistance to tuber skinning injury. This increase in resistance to skinning injury and associated changes in gene expressi

Technical Abstract: Mature native periderm that exhibits resistance to excoriation (RE) is the primary defense for potato (Solanum tuberosum L.) tubers against abiotic and biotic challenges. However, little is known about the physiology of periderm maturation and associated gene expressions. In this study, periderm maturation events and associated gene expressions were determined in tubers of two diverse potato genotypes (NDTX4271-5R (ND) and Russet Burbank (RB); 2008 and 2009 crops) at four harvest maturities ranging from immature to mature. Approximately 104 d after planting, accumulation of periderm phellem cell layers abated indicating cessation of cell division by the phellogen. Phellogen radial cell walls thickened as periderm matured throughout the harvests, increasing RE/skin-set. In both genotypes, the cell cycle gene cyclin-dependent kinase B (StCDKB) rapidly down-regulated after the second harvest coinciding with cessation of cell division. Expression patterns of genes encoding epidermal growth factor binding protein (StEBP) and cyclin-dependent kinase regulatory subunit (StCKS1At) were less indicative of phellogen inactivation and periderm maturation. Genes encoding the structural cell wall proteins extensin (StExt1) for ND and extensin-like (StExtlk) for ND and RB remained up-regulated respectively by the second harvest, suggesting involvement with completion of phellem cell accumulation and on-set of periderm maturation. The expression of genes encoding a cell wall strengthening “tyrosine-and lysine-rich protein” (StTLRP) and pectin methyl esterase (StPME) increased in phellogen cells from later harvests of ND tubers from the 2008 crop as did StExt1 for ND 2008 and ND 2009 crops; this suggestes roles in phellem cell generation and completion of delayed cell wall development in non-meristematic phellogen cells of ND, a red skinned phenotype. StCDKB and StPrePME genes were rapidly down-regulated by the third harvest for both genotypes. Collectively, these results suggest that down-regulation of these genes coordinates with on-set of periderm maturation and skin-set progression.

Last Modified: 7/30/2014