Identification of galactinol in potato tubers

Summary An oligosaccharide detected by gas chromatography of trimethylsilyl derivatives of potato extracts has been isolated and identified as galactinol, 1-0-α-D-galactopyranosyl-(1R)-myo-inositol. Galactinol was not detected in freshly harvested tubers, but 0.1% was found in cold-stored tubers. The level of this sugar decreased during reconditioning of cold-stored potatoes. A laboratory cooperatively operated by the Eastern Utilization Research and Development Division. Agricultural Research Service, United States Department of Agriculture; Minnesota Agricultural Experiment Station, North Dakota Agricultural Experiment Station; and the Red River Valley Potato Growers’ Association.     

Ultrastructure of potato tubers infected with potato virus X

The ultrastructure of Katahdin tubers infected with potato virus X (PVX) is compared with PVX-free tubers by electron microscopy. Electron-dense globules surrounding the inner periphery of the tonoplast were observed in PVX-infected tubers, while PVX-free tubers did not show such bodies. Other organelles were comparable in PVX-infected and PVX-free tubers     

Loss of yield in potato selections infested with potato leafhoppers

The loss of yield resulting from infestation with potato leafhoppers,Empoasca fabae (Harris), was measured in a group of potato selections (Solatium tuberosum subsp.tuberosum). For 6 years in which 300 different clones were tested, the average loss of yield was 39%. The correlation over clones between level of infestation and percent hopperburn equaled 0.56; between level of infestation and loss of yield 0.36; and between percent hopperburn and loss of yield 0.41. Each coefficient is significant at P=0.01. Significant differences were found in levels of infestation and in percent hopperburn among the selections, but even those selections with the most resistant foliage had greatly reduced yields when infested. No selections were found that consistently produced a normal yield when infested with leafhoppers. The low level of infestation on the more resistant clones, however, may make chemical control at lower rates more effective.     

Reinfection of potato seed stocks with potato virus S and potato virus X in Wisconsin

Reinfection of potato seed stocks with the potato viruses S (PVS) and X (PVX) varied with cultivar, virus, and grower. Rapid recontamination was observed for the cultivars Norgold Russet and Ontario with PVS and for the cultivars LaChipper, Norchip, and Norgold Russet with PVX. Recontamination was low for the cultivars LaChipper and Monona with PVS and for the cultivars Kennebec, Monona, Norland, and Superior with PVX. Survey results suggest that PVS and/or PVX can be eliminated from cultivars which appear to possess field resistance to infection, but that further evaluation of cultivars which are very susceptible to reinfection will be necessary.     

Identification of potato (solarium tuberosum L.) haploid x wild species hybrids with the capacity to cold-chip

Cold sweetening, the accumulation of reducing sugars in potatoes stored at low temperatures, results in dark chips unacceptable to the consumer. Developing potato cultivars that can chip directly from cooler temperatures (i.e., 3 to 4 C) requires the identification and use of new germplasm with cold-chipping resistance. Individuals from 16 haploid x wild species hybrid families were grown at two sites and their harvested tubers stored at 3 C for 15 wk. Following storage, individuals were evaluated for cold-chipping ability by (1) direct chipping, and (2) reconditioning for 2 wk at 18 C prior to chipping. At both sites, approximately 1% of progeny had good chip color (<2.0 rating using the Snack Food Association scale). Germplasm representing haploid x wild species hybrid families was evaluated for cold-chipping ability following storage of tubers at 3 C for 15 wk, and after storage at 18 C for 2 wk. The two cold-chipping clones identified with chip color means <2.0 were AH 66-1 and H 28-6, hybrids derived fromS. raphanifolium accessions 296126 and 310998, respectively.S. raphanifolium PI 296126 was exceptional in that chip color means of its progeny were 2.5 and 2.7 at McLeod (North Dakota) and Crookston (Minnesota), respectively. All clones with chip color means <2.6 involvedS. raphanifolium PIs 296126, 310998, and 458384 in their parentage. Following reconditioning, the number of progeny in the good and medium chipping categories improved from direct chipping with 14.1% of the progeny at McLeod and 3.8% at Crookston in the good chipping category.S. raphanifolium PIs 210048 and 310998 together accounted for 100% and 50% of the clones with chip scores <2.0 at McLeod and Crookston, respectively. Clones ranking high for chip color following direct chipping generally chipped well following reconditioning.     

Identification of stem soft rot (Erwinia carotovora subspeciesatroseptica) resistance in potato

Development of potato cultivars resistant to Erwinia species (Erwinia carotovora subspeciesatroseptica, E. carotovora subspeciescarotovora, andErwinia chrysanthemi) causing soft rot of stems and tubers involves identification and transfer of the resistance to breeding lines possessing desirable agronomic traits. In total, 363 accessions of six wildSolanum species, three somatic hybrids and nine sexual progeny of somatic hybrids were screened for stem soft rot resistance. Thirty-one, 50, and 67 percent of accessions ofSolanum boliviense, Solanum chacoense, and Solanumsanctarosae, respectively, were resistant or highly resistant, whereas, 100, 97, and 95 percent of accessions ofSolanum canasense, Solanum tarijense, andSolanum spegazzinii were susceptible or highly susceptible, respectively. Two tuber soft-rot resistant somatic hybrids, A937 and T355-11 produced earlier by the fusion ofSolanum brevidens (PI 218228) andSolanum tuberosum (PI203900) orS. tuberosum cv. Russet Burbank, respectively, and the sexual progeny of A937 andS. tuberosum cv. Katahdin were also highly resistant. Transfer of resistance fromS. brevidens to somatic hybrid (A937) and subsequently to the progeny suggests that the resistance is simply inherited. In addition to the identification of 65 resistant or highly resistant clones of wildSolanum species, this study has identified three tuber soft rot-resistant clones that are also resistant to stem soft rot. Potato cultivars showed a range of responses to the pathogen.     

Identification of potato cultivars and clonal variants by random amplified polymorphic DNA analysis

Random Amplified Polymorphic DNAs (RAPDs) were used to distinguish commercial potato cultivars and clonal variants of cultivars. Primer 131, one of four primers used, distinguished 30 of the 36 cultivars tested. All 36 commercial cultivars were distinguished using only two primers (131 and 184). The RAPD pattern of 20 unidentified potato cultivars was compared with known patterns of 36 cultivars. Each one of the 20 cultivars was correctly identified. Particular primers appear to produce greater numbers of both amplified DNA fragments and polymorphisms, and are therefore suited to RAPD identification of potato cultivars. Polymorphism was obtained between Russet Burbank Idaho D and Russet Burbank White Skin with primer 251 and between Viking and Purple Viking with primer 380. However, polymorphism was not observed between Norgold, Norland, Sebago and Superior clones using only 20 primers. The RAPD technique is much more likely to detect polymorphism, regardless of tissue or environmental factors, than isozyme analysis and is easier, less costly and faster than the RFLP procedure. Thus, RAPD analysis represents a highly useful method of distinguishing and identifying potato cultivars and clonal variants of cultivars.     

诱导甘薯开花的病原菌鉴定及其粗毒素对甘薯生长的影响

甘薯‘胜利百号’根腐病株为何出现显蕾开花的研究未见报告。本文鉴定了茄病镰孢甘薯专化型[Fusarium solani（Mart）Sacc．f.sp．batatas McClure，简称FSB]引起甘薯‘胜利百号’根腐病和诱导其显蕾开花（图1，2）。就FSB的V100-93-06菌株室内接种‘胜利百号’的接种方法、对不同甘薯栽培型的致病性及其粗毒素对甘薯组培苗叶片，芽的萌发数量和根的影响进行了研究。结果表明。切根接种和针刺接种方法较好（图3），V100—93-06菌株对不同甘薯栽培型呈现不同的致病性（表1），其粗毒素能够使组培苗出现黄叶（图4，5A），抑制芽萌发，抑制根长度和数量（图5），并能够诱导和病原菌寄生相似的部分症状（表2）。     

Identification of genetic factors influencing chip color in diploid potato (Solanum spp.)

A genetic map was constructed with a combination of isozymes, restriction fragment length polymorphisms (RFLPs) and randomly amplified polymorphic DNA (RAPDs) to apply quantitative trait loci (QTL) analysis to identify genetic factors that contribute to chip color in potato. The diploid population used was a cross between aSolanum tuberosum haploid andS. chacoense hybrid used as female parent and aS. phureja clone used as male. Chip color was determined visually on samples fried from tubers stored at 10C. On a scale of 1 (light color) to 10 (dark color), the population ranged from 2 to 8 while the parents average chip color was 3.5. Based upon one-way ANOVAs (P < 0.05), 13 genetic markers showed significant associations which represent a total of six QTLs. A multiple locus model based upon the markers that have the largest effect per QTL explained 43.5% of the phenotypic variation for chip color in the population and increased to 50.5% when one significant epistatic interaction was included in the model. All the significant marker associations were identifed in theS. tuberosum-S. chacoense hybrid. Through preliminary data, the results of this study suggest that additive effects contribute a significant portion of the genetic variation for chip color. The identification of these QTLs for chip color variation provides the means to apply marker-assisted selection to introgress these genes into the cultivated potato germplasm.     

New disease symptoms observed on field-grown potato plants with potato spindle tuber viroid and potato virus Y infections

Summary Potato spindle tuber viroid (PSTV) and potato virus Y (PVY) were isolated from plants of cultivar Kennebec with severe necrotic symptoms in the field. In the greenhouse, severe necrotic symptoms were reproduced only when potato plants were infected either simultaneously with PSTV+PVY, or with PSTV prior to PVY infection. Thirteen additional potato cultivars were tested in the greenhouse for this synergistic reaction and eight developed necrotic responses similar to cv. Kennebec. PVY concentration was significantly higher in doubly infected plants, compared with those infected with PVY alone.     

Identification of potato interspecific hybrids resistant toVerticillium wilt and determination of criteria for resistance assessment

Summary Verticillium dahliae causes potato (Solanum tuberosum) early dying disease. Interspecific hybrids containingS. tuberosum, S. berthaultii, S. bukasovii, S. chacoense, S. gourlayi, S. sparsipilum andS. tarijense were identified with resistance toV. dahliae. Clones were grown in replicated trials for three years in a plot containing approximately 50 colony forming units (cfu)V. dahliae per g soil. Clones were evaluated for vine maturity, early dying symptoms and stem colonization. Five resistant 2x clones were identified with early maturity and low levels of stem colonization. A single maturity score and one disease score, each obtained in mid-August, were sufficient to distinguish among clones. An effective threshold level for considering a stem to be infected was determined to be 25 cfu/100 μl sap. Early dying symptoms did not correlate strongly with stem colonization. Numerous stems must be sampled when making resistance assessments. The average cfu/100 μl sap correlated strongly with the number of infected stems.     

Production of potato starch with low waste

The use of fine grinding and air classification of dehydrated potatoes with sieving and minimum washing to produce potato starch is described. A substantial reduction in the amount of waste water over that required by conventional wet milling procedures was obtained. The procedure proposed would reduce wastes by 90%.     

Control of potato greening with household detergents

Greening and light-induced glycoalkaloid synthesis were inhibited for a period of 240 hours when tubers were immersed in a dilute detergent solution before exposing them to fluorescent light. The efficiency of the treatment was dependent on the variety and the length of time the tubers had been held in storage. A 30-minute treatment with 3% detergent solution inhibited chlorophyll development 92% for the first 48 hours in Russet Burbank tubers. The inhibitory effect decreased with increase in exposure time, but inhibiton remained more than 50% after 240 hours of continuous light exposure.     

A rapid micro-starch quantitation method for potato callus and its application with potato tubers

The procedure described was developed as a micro-starch method for potato callus tissue (0.1-0.2% starch on a fresh weight basis) and then evaluated with macro-starch samples of potato tubers harvested during three physiological stages of development. This method consisted of the following steps: (a) a mild alkaline-sonic extraction of starch from lyophilized 80% aqueous ethanol-washed samples, (b) starch hydrolysis of the neutralized, filtered extracts by 1 N HC1, and (c) the determination of liberated glucose by the specific glucose oxidase system. Results with this procedure were as sensitive and accurate (SD ± 0.86%) as with other starch-specific methods with more extensive starch isolation and purification steps.     

The treatment of potato tubers with sprout inhibitors

Summary Working with the sprout inhibitors IPC and CIPC we compared 3 treatment methods: (1) a 10 ppm dosage of powder distributed over the tubers, (2) a Swingfog treatment (atomizing a solution in the air duct, dosage up to 20 ppm), (3) a porous cartridge containing the inhibitor placed in the air duct. To obtain good sprout inhibition in connection with accumulated IPC/CIPC residue values below the legal level of 0.5 mg per kg peeled tubers we advise the powder treatment only for relatively long storage (up to May–June); a 10 or 20 ppm Swingfog treatment for short storage (up to January–February) or longer storage respectively. With the cartridge system we obtained promising results; good sprout inhibition and satisfactorily low residue values.     

Eradication of potato virus X from potato by ribavirin treatment of cultured potato shoot tips

Ribavirin treatment of cultured potato shoot tips was tested as a means of eradicating potato virus X (PVX) from two potato cultivars. Shoot tips were cultured on liquid medium containing 0, 1, 10 or 100μg/ml ribavirin. Cultures were evaluated periodically for viability, and scored for vigor on a relative growth scale. Developed plantlets were assayed for PVX by transmission tests toGomphrena globosa. Ribavirin treatment was phytotoxic at all tested concentrations, and lethal to all cultivars treated at 100 μg/ml. Treatment also delayed plantlet development by up to 2 months at 1 and 10 μg/ml as compared with nontreated controls. PVX assays indicated that 80 and 83% of the plantlets were free of PVX following treatment with 10 μg/ml for cultivars Russet Burbank and Red McClure, respectively. Five and 6% of the plantlets developed from the 1 μg/ml treatment were PVX-free, whereas 0 and 2% of the controls were PVX-free for the same cultivars. Six to 8 months were required to develop plants from shoot-tip cultures treated with 10 μg/ml ribavirin.