Starch and sugar content of potato tubers are quantitative traits, which are models for the candidate gene approach for identifying the molecular basis of quantitative trait loci (QTL) in noninbred plants. Starch and sugar content are also important for the quality of processed products such as potato chips and French fries. A high content of the reducing sugars glucose and fructose results in ...

The length of potato tuber dormancy depends on both the genotype and the environmental conditions during growth and storage. Abscisic acid (ABA) has been shown to play a critical role in tuber dormancy control but the mechanisms regulating ABA content during dormancy, as well as the sites of ABA synthesis, and catabolism are unknown. Recently, a temporal correlation between changes in ABA conte...

The potato tuber (Solanum tuberosum L.) ADP-glucose pyrophosphorylase activity is activated by a incubation with ADP-glucose and dithiothreitol or by ATP, glucose- 1-phosphate, Ca2+, and dithiothreitol. The activation was accompanied by the appearance of new sulfhydryl groups as determined with 5, 5'-dithiobis(2-nitrobenzoic acid). By analyzing the activated and nonactivated enzymes on SDS-poly...

The aim of this study was to evaluate the quality characteristics of seven yacon (Smallanthus sonchifolius Poepp. and Endl.) cultivars (Cajamarca, Cusco, Early White, Late Red, Morado, New Zealand and Quinault) cultivated in the southwest of Germany. The following phyto/chemical traits were investigated in different yacon tuber parts (flesh, peel, and whole tubers): total dry matter, sugar cont...

In this paper a process model for simulating the growth of sweet potato has been proposed. Vegetative developmental days (VDD) and reproductive developmental days (RDD) were calculated to predict crop phenology. Crop growth was divided into three phases, i.e., the first phase from planting to tuber initiation, the middle phase from tuber initiation to the beginning of tuber bulking and the fina...

Growing potato tubers or freshly harvested mature tubers have a dormant apical bud. Normally, this dormancy is spontaneously broken after a period of maturation of the tuber, resulting in the growth of a new sprout. Here it is shown that in in vitro-cultured growing and maturing tubers, ethanol can rapidly break this dormancy and re-induce growth of the apical bud. The in vivo promoter activity...

Erwinia carotovora subsp. betavasculorum strains produced a bactericidal antibiotic in vitro that inhibited a wide spectrum of gram-negative and gram-positive bacteria. The optimum temperature for production was 24 degrees C, and the addition of glycerol to culture media enhanced antibiotic production. Antibiotic production by these strains in the infection court of potato was the principal det...

The effects of three harvesting dates; 120 150 and 180 days after planting (DAP) and four potassium fertilizer levels; 0, 48, 72 and 96 Kg K2O fed -1 , on vegetative growth characteristics, tuber yield potential and quality of Jerusalem artichoke (cv. Balady) were studied. Two field experiments were conducted during the two successive summer seasons of 2001 and 2002 at the Experimental station ...

Disks of tuber tissue maintained in a moistened environment increase substantially in both protein content (18, 19, 21) and phenolic content (28). The 2 processes have not previously been considered as related. However, the stimulation by light of phenolic synthesis in tuber slices (11, 16) has been found to depend largely on the synthesis of proteins. Data which relate the production of phenol...

Lepidium meyenii, known in South America as maca, has received attention worldwide as a powerful energizer that improves physical and mental conditions and increases fertility. Because of these reports, we investigated the secondary metabolites of the tuber of maca. The methanol extract of the tuber of maca contained, in addition to free sugars and amino acids, the following: uridine, malic aci...