Late blight resistant potato germplasm release AWN86514-2

Potato breeding selection AWN86514-2, Solanum tuberosum gp tuberosum, is being released as germplasm that is highly resistant to prevalent North American strains of Phytophthora infestans. This selection has been tested under field conditions in Mount Vernon, Washington (P. infestans US11 and US8 with complex virulence pathotypes), as well as Corvallis, Oregon, and eight other locations in North America (predominantly P. infestans US8) between 1994 and 1997. Both foliage and tubers show partial resistance. Although AWN86514-2 is pollen sterile, it can be successfully used as a female parent. An average of 34% of the progeny from crosses between AWN86514-2 and four susceptible clones were resistant to late blight when tested at Toluca, Mexico, in 1996. AWN86514-2 also has high resistance to Verticillium wilt and potato virus Y. AWN86514-2 is late maturing, with medium yields of smooth, longoblong, buffskinned tubers. Specific gravity is high and french fry color from 7 C (45 F) storage is excellent. The male parent of AWN86514-2 was Ranger Russet, a dual purpose french fry and fresh market variety, and the female parent was KSA195-96, a selection made at Aberdeen, Idaho, from Polish germplasm received as true seed from the Polish Plant Breeding and Acclimatization Institute. Possible sources of the late blight resistance in this clone include S. acaule, S. demissum, S. phureja, S. simiplicifolium, S. stoloniferum, and S. tuberosum gp andigena which are in the lineage of KSA195-96. This germplasm was developed and released by USDA-ARS in cooperation with the Agricultural Experiment Stations of Idaho, Oregon, and Washington.     

Release of germplasm resistant to multiple races of potato cyst nematodes

Seeds of three progenies segregating for resistance to two pathotypes ofGlobodera rostochiensis (Rol and Ro2) and two pathotypes ofG. pallida (Pa2 and Pa3) are being released by the Cornell University Experiment Station and the USDA/ARS. This resistance is in a form suitable for North American production and was developed for use in the event that pathotypes ofG. pallida, which are prevalent in many other potato production areas of the world, are ever introduced into North America. The source of the resistance is germplasm obtained in 1984 from the International Potato Center in LaMolina, Peru. The combined resistance in this germplasm is fromS. tuberosum sspandigena andS. vernei. Resistance to PVY is also segregating in two of these progenies.     

Verticillium wilt resistant potato germplasm: A66107-51 and A68113-4

Potato breeding selections A66107-51 and A68113-4 (Solanum tuberosum gptuberosum) are being released as germplasm that is highly resistant to Verticillium wilt (Verticillium dahliae Kleb.) These selections have been extensively evaluated for resistance to Verticillium as measured by symptom severity and degree of colonization byV. dahliae. They combine outstanding wilt resistance with good tuber maturity characteristics, high yield, and french fry processing tuber type. A66107-51 has long-oblong, russeted tubers, with high yield and variable processing quality. A68113-4 has long-oblong, partially russeted tubers with high yield and good processing quality. Both selections are fertile as female parents, and A66107-51 is occasionally pollen fertile. The Verticillium resistance of these two clones has been transmitted to progeny. These selections were developed by USDA-ARS in cooperation with the Idaho Agricultural Experiment Station. Seed is available from USDA-ARS, Aberdeen, Idaho.     

The Inter-genebank potato database and the dimensions of available wild potato germplasm

The Association of Potato Inter-genebank Collaborators (APIC) constructed a database of all wild potato holdings of the most important potato genebanks in Europe, the United States, Peru, and Argentina. The Inter-genebank Potato Database (IPD) now contains data of 11,819 wild potato accessions conserved in seven potato genebanks. The collector’s number is the key identifier used to merge all databases into the IPD. A total of 7,112 different wild potato accessions were identified, which comprise 5,306 accessions with known collector’s numbers. The IPD passport database showed that almost 30% of accessions held in APIC genebanks are from Argentina, a country that comprises less species diversity than Peru and Bolivia. These latter countries are represented by 24% and 20% of accessions, respectively. APIC genebanks maintain 188Solarium taxa out of more than 230 recognized by the latest comprehensive treatment of potatoes(Solarium sect.Petota) by Hawkes (1990). About 60% of the accessions comprise only 20 taxa represented by 785 to 92 accessions each. Conversely, 2% of the accessions comprise 72 taxa and are represented by five or fewer accessions each. About 70 taxa are not available in any genebank. The IPD evaluation database comprises 5,603 records with data from more than 33,000 evaluations of wild potato accessions. Fifty-five traits are summarized, including the reactions of the accessions to 12 pathotypes or races or strains of 12 fungi, four bacteria, 12 viruses, one viroid, 13 nematodes, and seven insects; response to heat and cold stress; and content of dry matter, starch, vitamin C, amylase, reducing sugars, and glycoalkaloids. About 30% of the wild potato populations screened showed various levels of resistance to most of the diseases and pests evaluated. The IPD database is available on the Internet at www.potgenebank.org.     

Potato germplasm resistant to corky ringspot disease

Potato germplasm was assessed for resistance to corky ringspot disease (CRS) incited by transmission of tobacco rattle virus (TRV). TRV is transmitted by the stubby root nematode,Paratrichodorus allius, in the Pacific Northwest, and characterized by necrotic areas in the tuber. Four tests were conducted at two different problem fields in Umatilla, OR and Pasco, WA. The fields differed in the virulence of the virus isolates. Some clones and named varieties showed resistance only in the field with the relatively mild Umatilla isolate, while others remained symptomless at both sites. The host suitability of test potatoes to threeP. allius populations from the region was determined in greenhouse pot tests, and expressed as reproductive values [R_f = (final population of nematode at 55 days) / (initial population)]. TheR _f values for the nematodes were not correlated with resistance ratings based on visual scoring of CRS symptoms in field grown potatoes. Thus, it appears that CRS resistance is based on reaction of potato genotypes to virus and not the vector. The availability of resistant clones inin vitro form is indicated.     

ScreeningSolanum germplasm for resistance to Colorado potato beetle

TuberousSolanum accessions were screened for resistance to Colorado potato beetle (CPB),Leptinotarsa decemlineata (Say), in terms of CPB-caused defoliation in field trials with natural infestations of CPB. Cluster and multivariate discriminant analyses were used to distinguish among species and accessions. Several highly CPB-resistant and relatively homogeneous accessions were identified.     

Fine screeningSolanum (potato) germplasm accessions for resistance to Colorado potato beetle

This study was conducted to investigate the utility of systematic screening at the genotype level withinSolanum accessions highly resistant to the Colorado potato beetle. Evaluations of clonally replicated genotypes showed that most accessions reported to be uniform when screened as populations contained small but significant variation among genotypes for resistance to oviposition, larvae, and defoliation, differences for numbers of larvae being most common. Adult counts and percentage defoliation were not as useful in evaluating among-genotype variability in beetle resistance. Genotypes ofS. pinnatisectum WRF 343 andS. tarijense PI 473227 were the most uniformly and highly resistant to Colorado potato beetle. Genotypes of S.berthaultii PI 473331,S. chacoense PI 473405, andS. tarijense PI 473336 were moderately to highly resistant, and genotypes ofS. bukasovii PI 473494 andS. canasense PI 230511 were uniformly susceptible to Colorado potato beetle. Nonparametric correlation analyses indicated that number of egg masses, small larvae, large larvae, and defoliation scores were positively correlated, negatively correlated, or not correlated, depending on the species. One generation of selection attempting to segregate resistance and susceptibility in nearly uniform and highly resistantS. pinnatisectum WRF 343 resulted in “divergent” populations that could not be distinguished from each other or the base population. Thus, through genotype (“fine”) screening and selection, we showed that some existing populations are virtually pure for extreme resistance. Use of individuals from such families would make screening breeding populations more efficient, and reduce the risk of losing resistance genes that have non-dominant effects. Fine screening, recurrent selection, and maintenance of such elite populations is recommended as an extension of population-based evaluation usually done by genebanks.     

The germplasm release of B0718-3 and B0767-2: Two late blight resistant potato clones

Two potato breeding selections were released by the United States Department of Agriculture, Agricultural Research Service on November 14, 1996, as germplasm that is highly resistant to current populations ofPhytophthora infestans (Mont.) deBary, the causal organism of potato late blight: B0718-3 and B0767-2. These two clones have been evaluated for their reaction toP. infestans in replicated plots at Presque Isle, Maine since 1990. B0718-3 is a netted white-skinned selection with good yields but low specific gravity. It is both male and female fertile and crosses readily with tetraploid Tuberosum. B0767-2 is a russet-skinned selection that is low yielding and low in specific gravity. It has not been successfully crossed; however, it may have some potential use in somatic hybridizations. Neither B0718-3 nor B0767-2 process into acceptable colored chips. Genetic material of this release has been deposited in the National Plant Germplasm System where it is available for research purposes, including development and commercialization of new cultivars.     

大豆抗锈种质的评价

对14个国内外大豆抗锈种质在福建地区的抗锈性及农艺性状进行了评价。结果表明:抗锈基因Rpp1、 Rpp2、Rpp3和Rpp4 (屏南豆)的抗性已被克服,抗锈种质樟子乌、九月黄和日向可能含有新的抗锈基因。来自国外 的抗锈种质在福建地区未能表现出对锈病的抗性,农艺性状较差,不适宜直接利用。     

Mexico, 1988 potato germplasm collecting expedition and utility of the Mexican potato species

A joint Danish, Mexican, United States wild potato (Solanum sect.Petota) germplasm collecting expedition was conducted in Mexico between Aug. 21-Oct. 20, 1988. The trip resulted in 93 seed and 25 tuber collections of 18 species and one putative natural hybrid,S. xmichoacanum. Rare species collected include:Solanum darum,S. hintonii,S. lesteri, andS. xmichoacanum. First germplasm collections were made of the disjunct populations ofS. fendleri from Baja California. The potential and realized breeding value of these species is discussed.     

Wild potato (Solanum sect.Petota) germplasm collecting expedition to Argentina in 1990, and status of Argentinian potato germplasm resources

Summary A joint Argentina/United States expedition collected wild potato (Solanum sect.Petota) germplasm in Argentina between February 4–28 and March 28–April 18, 1990. This was followed by a short expedition between February 27 and March 3, 1991. Collections were made in the Andes Mountains from southern Tucumán Province (27°20′S), south to southern Rio Negro Province (40°52′S) and comprised 88 lots of germplasm of ten species, 76 as true-seed and 12 as tubers. The most important new collections included germplasm ofS. brevidens, S. maglia, S. x rechei andS. venturii. By summarizing details of these collections with those of existing collections, we have been able to suggest future collecting in Argentina.     

Exploration,conservation and evaluation of potato germplasm in Argentina

Summary The activities of the Potato Germ Plasm Centre at Balcarce, Argentina, since its creation in 1970, are outlined. This Centre was developed by INTA (National Institute of Agricultural Technology) with West German bilateral assistance. Several collecting expeditions have been organized to north-western Argentina and as a result a valuable collection of germplasm is now available to potato breeders from both national and international institutions. Evaluation and utilization of this material are also being actively pursued, and the need for close international cooperation and coordination is stressed.     

芝麻抗茎点枯病及枯萎病种质的评价

1997－1998年,对“八五”期间收集的芝麻种质资源初鉴获得的高抗茎点枯病和高抗枯萎病种质共85份及4个育种单位提供的8个新品系,在芝麻主产区三个生态试验点（病圃）进行了鉴定评价,均与当地优良品种进行比较,评价出抗性稳定、相对病情指数＜15％的抗茎点枯病种质34份、抗枯萎病种质38份,其中兼抗两种病害的27份,并明确了不同基因型抗源在不同生态系统中的抗性表现及利用价值、对抗、感品种酯酶同工酶分析表明,在A区检测出感病品种的相似性和抗、感品种间的带型差异。     

Alasclear: A high quality scab resistant potato

Alasclear was released from the breeding program at Palmer to provide Alaskan potato growers with a variety as resistant to potato scab as Ontario and of much better quality than that variety. Alasclear has a clear skin and is very acceptable at harvest for chip manufacture. Ninety days from planting it accumulated high dry matter as indicated by 1.089 specific gravity. It continues to increase to 1.102 specific gravity over a period of 120 days.     

Breeding potato cultivars with tubers resistant toPhytophthora infestans

Summary Available information has been reviewed on tuber resistance toP. infestans, its inheritance and breeding procedures used to obtain potato cultivars superior in this character. P. infestans is worldwide the most destructive potato pathogen. Tuber resistance is an essential component of potato resistance as this pathogen is often responsible for tuber rot in storage, and infected tubers of susceptible cultivars provide an important way for its overwintering. In Europe many cultivars and advanced breeders selections have been obtained with tuber resistance toP. infestans, but in the last decades no progress is noted in the mean level of this resistance in cultivars. The expression of tuber resistance depends to a large extent on testing conditions and therefore it can be difficult to evaluate. Consequently making progress in breeding is not easy, and also cultivar assessment data from various countries sometimes differ considerably. It is concluded from published data that it should be easier to make progress in breeding potato cultivars with resistant tubers if more attention is paid to combining the various types of resistance which are already known, and if the genetic determination of durable resistance toP. infestans is better understood. Professor Dr. K.M. Świeżyński passed away on 27th July 2000     

Diploid potato germplasm derived from wild and land race genetic resources

Diploid cultivated species, haploids derived from tetraploid cultivars, and their wildSolanum relatives were used to generate various diploid potato genetic stocks. These stocks have significant value in potato breeding because: 1) genetic diversity in the potato population can be kept variable with the diploid germplasm which confers genetic variation from wild and cultivated species; 2) crossability of this diploid germplasm is facilitated by the function of 2n gametes; and 3) high levels of pest resistances originating from the process of introgression of the wild and cultivated genetic resources can be used to improve the tetraploid cultivated potato genepool.     

Screening of exotic potato germplasm for nitrogen uptake and biomass production

Exotic potato germplasm may contain useful traits for improving nitrogen (N) use efficiency in cultivated potatoes (Solanum tuberosum L.). The objective of this study was to evaluate a “mini” core collection of wild germplasm for biomass production, N uptake, and N use efficiency. A field study was conducted during the 1993 growing season on a loamy sand soil at Becker, Minnesota. Uniform transplants for 39 wild accessions and 3 varieties were grown under greenhouse conditions, and after 40 days, they were transplanted to the field. Plants were subjected to two N treatments, 0 and 225 kg N ha¹, replicated three times in a split-plot design. Plant parts were collected separately 111 days after transplanting, dried, weighed, and analyzed for N concentration. Nitrogen rate and potato species had significant effects on total dry weight, N content, and tissue N concentration. The regression coefficient of N concentration on total dry weight was very low (r=0.22, NS), whereas the regression coefficient of total N content on total dry weight was high (r=0.94, P>0.001). At both low and high N environments, Russet Burbank had greater dry weight than all the accessions. Several wild accessions, especiallyS. chacoense, S. commersonii, S. kurtzianum, S. microdontum, andS.phureja, had equal to or greater dry weights than Russet Norkotah or Red Norland. For N uptake efficiency, 2,7, and 20 accessions were ranked better than Russet Burbank, Russet Norkotah, and Red Norland, respectively. Recovery of soil applied N by the varieties ranged from 16 to 36%; the top seven wild accessions recovered between 27 and 49%. Based on plant growth without added N fertilizer and relative response to N fertilizer, the species were categorized into four relative N use efficiency groups: good foragers with good response to N, poor foragers with good response to N, good foragers with poor response to N, and poor foragers with poor response to N.