Volunteer potatoes as a source of potato leafroll virus and potato virus X

Volunteer potatoes were investigated as infection sources for potato leafroll virus (PLRV) and potato virus X (PVX) in a high elevation seed potato growing area of eastern Idaho. Population densities ofMyzus persicae were assessed. Percentage of PLRV and PVX infection of the volunteers and seed potato crops was determined, as well as density of volunteers and certain parameters of volunteer growth and reproduction. Volunteers apparently harbored no more PLRV than the potato crop from which they originated. But they were found to be an important reservoir of PVX with the infection increasing as much as 12.43% in one year. No aphids capable of transmitting PLRV were found although one species that can transmit potato virus Y was recorded. The mean density of volunteers varied from 0 to 84,880 stems/ha. The number of tubers remaining in the field after harvest and winter weather conditions appeared to be the only factors affecting volunteer density. Volunteer plants arising from seed pieces at an average depth of 6.1 cm were found to set an average of 2.1 new tubers per plant at an average depth of 4.0 cm. These results suggest that volunteer potatoes are a significant source of PVX infection in subsequent seed potato crops.     

Enzyme-linked immunosorbent assay (ELISA) for the detection of potato leafroll virus and potato virus Y in potato tubers after artificial break of dormancy

Summary Conditions necessary for the detection of potato leafroll virus (PLRV) and potato virus Y (PVY) in tubers from primary and secondary infected plants were investigated. Tubers were analysed before and after breaking dormancy by rindite treatment. PLRV was reliably detected indormant tubers whereas PVY was readily detected only when tubers had been rindite-treated and held for two to three weeks at 22°C and high humidity in the dark. PLRV occurred in higher concentration at the heel end than at the rose end of infected tubers and the concentration remained nearly unchanged during the experimental period of 35 days, whereas PVY was found to be more concentrated at the rose end and was rapidly accumulating in the tubers after the break of dormancy. In dormant tubers PVY concentration dropped during storage at 22°C. The use of ELISA for tuber indexing is discussed.     

Effect of time of inoculation with potato leafroll virus on development of net necrosis and stem-end browning in potato tubers

The Green Mountain cultivar was used in field tests to determine the effects of inoculating potato plants at various times with the potato leafroll virus (PLRV) on development of internal necrosis of tuber tissue. Viruliferous apterae of the green peach aphid,Myzus persicae (Sulz.), were placed on each stem in all hills to be inoculated in each 3.0 m single-row plot. Planting and inoculation dates were varied in all field experiments and, in one, several vine-killing dates were also included. All harvested tubers were stored for approximately four months at 10°C to enhance development of internal necrosis prior to examination. Similar but smaller greenhouse studies involving both apterous and alate green peach aphids were also conducted using Green Mountain, Irish Cobbler, and Russet Burbank cultivars. All results showed that as inoculation was delayed relative to plant development, more net necrosis (NN) occurred. Conversely, when plants were inoculated early, stem-end browning (SEB) rather than NN predominated. A high percentage of naturally occurring SEB tubers (cv. Russet Burbank) were found by ELISA to contain PLRV. Plants produced by these tubers only rarely developed leafroll symptoms. These findings suggest a previously unsuspected causal relationship between SEB and PLRV. Implications of this apparent relationship on the epidemiology of potato leafroll in Maine are discussed.     

Allagash Russet: A new potato variety from maine

The Allagash Russet potato is an early to mid-season variety with oblong, attractive, uniformly-russeted tubers. Resistance of tubers to skinning and bruising during handling, and slow sugar build-up in cold storage are two advantages of this all-purpose potato. Tubers do not show the net necrosis associated with leafroll virus infection, and are moderately resistant to common scab.     

Incidence, appearance and development of potato mop-top furovirus-induced spraing in potato cultivars and the influence on yield, distribution in Denmark and detection of the virus in tubers by ELISA

Summary 23 potato cultivars were grown in fields infested with potato mop-top virus and spraing was assessed on tubers at harvest and after storage. Large differences in spraing susceptibility were found between cultivars. Compared with other countries, spraing in Denmark is characterised by a high incidence at harvest, a low increase during storage and a very low proportion of superficial spraing. Decrease in spraing during storage was recorded in two cultivars. DASELISA tests for PMTV in tubers revealted a high reliability. Mapping of PMTV in important Danish potato growing areas showed that the virus is widespread. Occurrence of spraing did not influence total yield or dry matter content. Soil acidity did not influence incidence of spraing but it was more common on coarse-grained soil than on finer sandy soils. PMTV in viruliferous resting spores ofSpongospora subterranea was inactivated by heating to 90°C for 15 minutes.     

Epidemiology of potato leaf roll virus in the Fraser River delta of British Columbia

The spread of potato leaf roll virus (PLRV) and the resulting phloem necrosis in the tubers has been a limiting factor in the production of the Netted Gem (Russet Burbank) variety in southwestern British Columbia, Canada. Steckling sugar beets are an important overwintering host for nymphs and adults of the green peach aphid,Myzus persicae (Sulzer). By June, aphids are widely disseminated to the florets and new leaves of sugar beet and other hosts, including potato. Colonies with alates are produced on summer hosts which are not treated with insecticides. The peak of the flight of alates from the colonies on the summer hosts occurs during the first half of August. Those alates that were produced on PLRV-infected potato and which travel to other potatoes transmit the virus as soon as they feed. By the end of August, the sugar beet seed crops and the early and mid-season potato crops have been defoliated or harvested. Thus many colonies ofM. persicae are destroyed and the threat of PLRV spread diminishes. Crop and weed plants which serve as overwintering hosts become infested during late summer with alate aphids. Their offspring survive the winter in numbers which are determined by the weather and survival of host plants.     

Mainestay: A high-yielding, round white potato variety for fresh market

The Mainestay potato variety is high-yielding and late-maturing producing attractive, round, white-skinned, white-fleshed tubers with medium-shallow eyes. Its major use is expected to be as a maincrop tablestock variety. Mainestay appearance ratings are similar to those of Katahdin, and greening in Mainestay tubers is less than in Kennebec. Most boil and bake qualities were rated equal to Katahdin in at least half of the tests, and Mainestay usually has a low incidence of internal defects. However, purple streak, heat necrosis, vascular discoloration, and heat sprouts have been seen on occasion. Mainestay tubers do not show the net necrosis caused by potato leafroll virus, and have shown very little hollow heart or blackspot bruising. Mainestay is susceptible to common scab and acid scab, but moderately resistant to verticillium wilt (Verticillium, albo-atrum andV. dahliae), early blight (Alternaria solani), rhizoctonia (Rhizoctonia solani), dry rot (Fusarium sambucinum), and pink rot (Phytophthora erythroseptica). It is moderately susceptible to the common race of late blight (Phytophthora infestans). Mainestay tubers are slow to mature after vine kill, and additional time is required prior to harvest in order to allow for proper periderm development and to reduce storage losses.     

Potato leafroll virus concentration in the vascular region of potato tubers examined by enzyme-linked immunosorbent assay (ELISA)

Summary Enzyme-linked immunosorbent assay (ELISA), used in conjunction with a new rapid extraction method, showed that potato leafroll virus (PLRV) concentration in the vascular region of infected potato tubers decreases from the heel to the rose end. Lower virus concentration at the rose than at the heel end was found not only in dormant tubers but also in tubers three weeks after breaking dormancy although the difference was then less pronounced. These results were obtained from plants with both primary and secondary infection by one of two French virus isolates which behave differently in respect of either accumulation in the ants or in their serological properties or both.     

Relationship between cultural practices and the occurrence of volunteer potatoes in the Columbia Basin

The time of tillage practices following potato harvest in the Columbia Basin affected numbers of volunteer potato plants that emerged. The best control was achieved by waiting after harvest until tubers on the surface were frosted at least once and then plowed to expose additional tubers from below the frost. Planting a wheat cover crop after plowing further reduced numbers of volunteers. Foliage treatment with maleic hydrazide to prevent sprouting gave excellent volunteer control in one season and poor control the next. Soil fumigation with Telone C-17 gave excellent control of volunteers. Properly timed tillage combined with use of a wheat cover crop was as effective as the chemical treatments in reducing numbers of volunteers.     

Yankee Chipper: A new golden nematode resistant potato variety with wide adaptation in the northeastern United States

The Yankee Chipper potato is a medium maturing variety with round to oblong, smooth, white-skinned tubers. Acceptable yields, good dry matter and light chip color characterize this widely adapted variety. It is resistant to golden nematode and virus X, and tubers do not show the net necrosis associated with leafroll virus infection.     

Transmission of potato leafroll virus to or from tuber slices by aphids feeding through a membrane

Summary Eye-bearing slices, cut from healthy potato tubers and placed between Parafilm membranes, were inoculated with potato leafroll virus (PLRV) byMyzus persicae. PLRV was detected by ELISA and by transmission tests in tuber slices and in plants grown from the slices of the susceptible cv. Désirée, but not in those of the resistant cv. Arkula. These results suggest that PLRV replication and transport within tuber phloem is controlled by specific mechanisms of resistance.M. persicae was also able to acquire and transmit PLRV toPl floridana from slices cut from tubers of infected plants. The aphids effectively transmitted PLRV from slices cut from the sprouting rose end but they failed to transmit it from slices cut from the heel end of tubers.     

Effect of time and date of inoculation,plant age,and temperature on translocation of potato leafroll virus into potato tubers

Movement of potato leafroll virus (PLRV) to tubers following placement of viruliferous aphids on foliage was studied on the medium-maturing cultivar, Katahdin and the late-maturing cultivar, Russet Burbank. Inoculation was begun on August 20 and continued at three-day intervals until mid-September. There was no trend of increasing or decreasing numbers of leafroll-infected tubers from early to late inoculation. Several variables were examined to determine their effects on the incidence of PLRV-infected tubers. Multiple regression analyses showed that inoculation date, maximum daily temperature, minimum daily temperature, plant age, and length of time from inoculation to harvest explained 38% of PLR incidence in tubers of cv. Katahdin. Length of time from inoculation to harvest and minimum daily temperature explained 40% of PLR incidence in tubers of the cv. Russet Burbank.     

Yankee Supreme: A new bruise-resistant potato variety

The Yankee Supreme potato is a medium to medium-late maturing variety with round to oblong, moderately smooth, shallow-eyed, buff-colored tubers. It is characterized by bruise resistance and high dry matter. Tubers can be used for fresh market or processing. Although chip color is often marginal, this variety can be reconditioned to its original color after cold storage. Yankee Supreme is resistant to virus X and to net necrosis caused by the leaf-roll virus.     

马铃薯病毒外壳蛋白融合基因转化马铃薯及其抗病性分析

将多种病毒的有效核酸片断拼接成融合基因转入马铃薯可获得多抗马铃薯材料。针对马铃薯生产中分布广泛、危害严重并经常混合感染的马铃薯X病毒(PVX)、马铃薯Y病毒(PVY)、马铃薯卷叶病毒(PLRV)和马铃薯S病毒(PVS),开展了利用基因工程方法获得兼抗4种马铃薯病毒转基因马铃薯材料的研究。试验在前期获得含4种马铃薯病毒外壳蛋白基因片段的质粒pART27-XSYV-rh的基础上,通过根癌农杆菌(Agrobacterium tumefaciens)介导转化马铃薯(Solanum tuberosum)品种‘陇薯3号’,PCR扩增和PCR-Southern杂交证明,4价融合基因已整合到马铃薯基因组中。qRT-PCR分析表明,该融合基因在转基因植株中能正常表达。3株转基因植株的抗病性鉴定结果表明,2株对4种病毒同时具有抗性;1株对PLRV侵染表现阳性,对另外3种病毒同时具有抗性。     

Portage: A new early-maturing,round white table potato variety

The Portage potato variety is high-yielding and early-maturing with attractive, round to oblong, white-skinned, white-fleshed tubers with medium-shallow eyes. Its major use is expected to be as an early tablestock variety in areas where Superior suffers yield reductions caused by verticillium wilt. Portage tubers do not show the net necrosis caused by potato leafroll virus, and are susceptible to skinning, but are fairly resistant to hollow heart, blackspot and shatter bruise. Portage is moderately resistant toVerticillium alboatrum, andRhizoctonia solani, but its seed-pieces are sensitive to dry soil conditions; therefore, cut seed should be suberized before planting. Symptoms of leafroll virus infection are difficult to recognize.     

Butte: A long Russet potato variety with excellent dehydrating quality

‘BUTTE’, a new long russet potato variety, was released by the Agricultural Research Service, U. S. Department of Agriculture and the Idaho, Oregon, and Washington Agricultural Experiment Stations in April, 1977. Its tubers are similar to those of ‘Russet Burbank’ but BUTTE offers several advantages to growers and processors. BUTTE has averaged 7% more total yield and 25% more U.S. No. 1’s than Russet Burbank over 51 location-years of testing across southern Idaho, eastern Oregon, and in the Columbia Basin. Its specific gravity in these trials averaged .004 higher than that of Russet Burbank. Dehydrating quality of BUTTE is superior to that of Russet Burbank and the product has longer shelf life. BUTTE french fries well although it accumulates slightly more sugars in storage than does Russet Burbank. Its vitamin C content has averaged 58% higher and protein content 20% higher than that of Russet Burbank. BUTTE is hypersensitive to virus X and resistant to net necrosis. Other disease reactions are similar to those of Russet Burbank.     

Monitoring current season potato leafroll virus movement with an immunosorbent direct tissue blotting assay

A direct tissue blotting assay (DTBA) was used to track the movement of potato leafroll virus (PLRV) from newly infected foliage to the tubers. Plant and tuber characteristics were recorded to assess plant growth stage at inoculation and PLRV effect on yield. Russet Burbank potatoes were planted at different times in 1991 and 1992 to provide plants of different maturities which were then inoculated using PLRV carrying aphids. Aphids were allowed to feed two to three days after which an insecticide was applied. Stems and tubers were tested periodically for PLRV with DTBA after inoculation. Indexed tubers were grown out and ELISA tested in the greenhouse the following winter to confirm results of summer serological tests. Plant age affected percentages more consistently than did inoculation date. When plants approximately 43 days from planting were inoculated at different dates, early inoculation produced a higher percentage of infected plants. Conversely, when plants approximately 62 days from planting were inoculated at different dates, late inoculation resulted in a higher percentage of infected plants. However, early inoculation of young plants resulted in the highest infection percentages. Tuber size and yield were negatively affected by higher percentages of leafroll regardless of the stage of growth at inoculation. DTBA is best used for detecting PLRV in foliage of plants grown from infected tubers (i.e. secondary PLRV). DTBA is less accurate for detecting primary PLRV.     

Simplified extraction method for ELISA and PCR detection of potato leafroll luteovirus primary infection in dormant potato tubers

This report describes a simple, rapid and inexpensive procedure for sampling large numbers of dormant tubers for analysis of potato leafroll luteovirus (PLRV) infection. The procedure uses a common electric drill to simultaneously remove and macerate tuber-eye samples for detection of PLRV by the enzyme-linked immunosorbant assay (ELISA) and the polymerase chain reaction (PCR). By using these sampling and analysis approaches, 19 of 20 different PLRV isolates were detected in dormant tubers from plants with primary infections. Results from the dormant tuber analysis, were verified by planting the tubers and testing leaf tissue by ELISA and PCR. Similar sampling and testing done on healthy dormant tubers and sprouts from the tubers consistently gave negative results as expected.