Frost tolerance in wild potato species: Assessing the predictivity of taxonomic, geographic, and ecological factors

The use of genetic resources could be more effective and efficient if we were able to predict the presence or absence of useful traits in different populations or accessions. We analyzed the extent to which taxonomic, geographic and ecological factors can predict the presence of frost tolerance in wild potatoes. We used screening data for 1646 samples from 87 species that had been collected in 12 countries in the Americas. There was a strong association of frost tolerance with species and to a lesser extent with taxonomic series. There was significant geographic clustering of areas with wild potatoes with similar levels of frost tolerance. Areas with a high level of frost tolerance are the central and southern Peruvian Andes, the lowlands of Argentina and adjacent areas, and a small area in the central Chilean Andes. There is a greater chance of finding wild potatoes with high levels of frost tolerance in areas with a yearly mean minimum temperature below 3 ^°C than there is in warmer areas. However, temperature is only a weak predictor of frost tolerance. Temperature data alone did not predict observed frost tolerance in eastern Argentina/Uruguay and falsely predicted it in the southwestern United States. Because many wild potato species occur over small areas, taxonomic, ecological, and geographical factors are difficult to disentangle. This revised version was published online in July 2006 with corrections to the Cover Date.     

Bolivia potato germplasm collecting expeditions 1993, 1994: Taxonomy and new germplasm resources

Summary We conducted joint Bolivia/The Netherlands/United States wild potato (Solanum sect. Petota Dumort.) germplasm collecting expeditions in Bolivia from February 1-April 15, 1993, and January 1-February 26, 1994. The goals of the expeditions were to collect germplasm and gather data for continuing taxonomic studies of the approximately 43 taxa of Bolivian wild potatoes accepted by current taxonomists. We made 223 collections, 135 as true seed collections, 54 as tubers, 19 only as herbarium collections. Two recent taxonomic treatments of Bolivian wild and cultivated potatoes have clarified the taxonomy and distribution of these plants, but there are continuing disagreements between treatments regarding species boundaries and interrelationships. These disagreements, and the variability we observed in natural populations, present problems for identifications. We summarize the state of germplasm collections for Bolivia, provide our field data regarding the taxonomy of Bolivian wild potatoes, provide recommendations for future collecting, and provide new chromosome counts for S. hoopesii, S. ugentii, and S. yungasense.     

A test of taxonomic and biogeographic predictivity: resistance to Potato virus Y in wild relatives of the cultivated potato

A major justification for taxonomic research is its assumed ability to predict the presence of traits in a group for which the trait has been observed in a representative subset of the group. Similarly, populations in similar environments are expected to be more alike than populations in divergent environments. Consequently, it is logical to assume that taxonomic relationships and biogeographical data have the power to predict the distribution of disease resistance phenotypes among plant species. The objective of this study was to test predictivity in a group of widely distributed wild potato species, based on hypotheses that closely related organisms (taxonomy) or organisms from similar environments (biogeography) share resistance to a simply inherited trait (Potato virus Y [PVY]). We found that wild potato species with an endosperm balance number (EBN) of 1 (a measure of cross compatibility) shared resistances to PVY more than species with different EBN values. However, a large amount of variation was found for resistance to PVY among and within species. We also found that populations from low elevations were more resistant than those from high elevations. Because PVY is vectored by aphids, we speculate that the distribution of aphids may determine the level of selection pressure for PVY resistance.     

In vitro infection of bovine alloreactive cytotoxic T cell lines with sporozoites of Theileria annulata and T parva

Bovine alloreactive cytotoxic lymphocyte (CTL) lines of known target specificity were infected in vitro with sporozoites of Theileria annulata and T parva and cultured in limiting dilution. The phenotypes of the CTL lines both pre- and post infection were assessed using a panel of monoclonal antibodies specific for defined bovine lymphocyte subpopulations. The effector function of the resultant infected cell lines was determined using a Cr51 release assay and compared to the uninfected control CTL line. The results indicated that T parva sporozoites consistently infected and transformed the CTL lines very efficiently even at the lowest cell doses. In contrast the T annulata sporozoites were largely unable to infect and transform the alloreactive CTL except at the very highest cell and sporozoite doses. A factor which appeared to influence susceptibility to T annulata infection was an increased level of class II expression on the CTL line. None of the cell lines showed cytotoxic effector function after infection with either T annulata or T parva sporozoites.     

Studies on the major histocompatibility complex of indigenous cattle in the Ivory Coast

The MHC (BoLA) type has been determined for cattle from three breeds in West Africa. Seventy Baoule, 50 N'Dama and 30 Zebu cattle from the centre and north of the Ivory Coast were tested. Lymphocytes from these cattle were tested in a lymphocytotoxicity test with alloantisera detecting all of the internationally recognised BoLA sera. 78 sera prepared in Edinburgh and 57 in Jouy-en-Josas were used in the study. The results showed that sera prepared in Europe detect similar specificities in West Africa. Although with some specificities the frequencies differ from those seen in Europe. The frequency of null alleles is higher than in Europe in the Ndama and Zebu animals indicating the existence of additional specificities which will require the production of alloantisera in these breeds. However in the Baoule the null allele frequency is lower even then in some European breeds. The population data in which no animals have more than two workshop specificities is consistent with a single locus control in West Africa as in Europe.     

Polypeptide and antigenic variability among strains of Mycoplasma ovipneumoniae demonstrated by SDS-PAGE and immunoblotting

Comparison of the polypeptide patterns of 22 isolates of M. ovipneumoniae by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed a marked degree of heterogeneity with only limited groupings identifiable. Of the 50 major polypeptides identified in one strain (956/2), 35 were shown to be antigenic using immunoblotting with a homologous polyclonal serum. Radioimmune precipitation of 125I-surface-labelled proteins and phase partition using Triton X-114 detergent indicated that these were membrane associated. Cross-reactivity between the isolates was examined by immunoblotting using one polyclonal serum and four monoclonal antibodies (MAbs), all raised against strain 956/2. The polyclonal serum revealed considerable antigenic heterogeneity, but at least nine major antigens were conserved across all isolates. Two MAbs cross-reacted with all 22 strains, but the other two MAbs allowed some differentiation of the strains. One (MO/3) divided the isolates into groups of 16 and 6 based on the presence of absence of a 26-kDa antigen. All strains isolated from sheep with pulmonary adenomatosis fell into the smaller group and did not possess the 26-kDa antigen.     

Culling and wastage in dairy cows in East Anglia

A culling survey in 80 Friesian dairy herds in East Anglia over four years investigated the age at, and reasons for, disposal or death. Failure to conceive was the most important reason except in very old animals. Low production was the second most common reason, culling being particularly heavy in the first two lactations. Mastitis was the major disease influencing wastage and increased with age until the sixth lactation. The percentage of culls for multiple reasons increased with age. There was a high proportion of young animals in most herds and the median lactating life of cows was about three years, equivalent to three lactations. Considerable variation in herd life demonstrated that there was substantial scope for improving herd longevity. Long living herds culled fewer animals for breeding problems in the early lactations and for mastitis in the later ones, enabling more animals to be culled as surplus and for production factors.     

Wild potato (Solanum sect.Petota) germplasm collecting expedition to Mexico in 1993, with special reference toSolanum bulbocastanum Dunal andS. cardiophyllum Lindley

Summary A joint Mexico/United States expedition collected wild potato (Solanum sect.Petota) germplasm in Mexico between August 1–31, 1993. The purpose of the expedition was to expand germplasm and herbarium collections ofS. bulbocastanum andS. cardiophyllum. Collections were made from west-central to southern Mexico, and comprised 19 true seed and 37 tuber collections (45 collections in total) of 9 species and two putative natural hybrids.     

Genetic diversity and origin of cultivated potatoes based on plastid microsatellite polymorphism

The origin of cultivated potatoes has remaining questions. In this study, 237 accessions of all cultivated species and 155 accessions of wild species closely related to cultivated potatoes, including their putative ancestors, were analyzed using 15 plastid microsatellites (SSRs) to investigate genetic diversity and their relationships with the wild species. We here used polymorphic plastid SSRs we developed from potato plastid genome sequences as well as already known plastid SSR markers. All 15 loci were polymorphic and identified a total of 127 haplotypes. Dramatic decreases in levels of genetic diversity were revealed in landraces in comparison with wild ancestor species. The plastid SSR results showed a decrease in haplotype number and diversity from Peru to both north and south. Phylogenetic analysis revealed two distinct groups. One of them, group A, contained the majority of accessions of cultivated species of the Solanum tuberosum Andigenum group including all accessions of cultivated diploid and triploid cytotypes of this group (S. chaucha, S. phureja, and S. stenotomum by a former taxonomic system) and most of tetraploid accessions of the S. tuberosum Andigenum group (S. tuberosum subsp. andigenum), and the majority of accessions of wild ancestors from the northern members of the S. brevicaule complex. Another group B comprised most of the wild species accessions and almost exclusively hybrid cultivated species which have introgressed plastid genomes from the other wild gene pools. Lack of clustering of traditional cultivated species (as used above) support a revised group classification of S. tuberosum.