Statistical method for testing the neutral mutation hypothesis by DNA polymorphism.

K. SALAMAN, after 40 years of research on genetD ical, morphological, pathological, and related studies of the potato, and 9 years in the preparation of the material, presents the most comprehensive book that has been published on this subject. He shows by the records of the ancient Peruvian pottery that the potato was cultivated as early as the second century A.D., and that it influenced considerably the art and the social and religious customs of the ancient civilizations of the Andean plateaus. He discusses the potato in pre-Spanish Peru, and by documentary evidence shows that Costellanos was the first white inan to find and describe the potato and not Cieza de Leon who has for years been given the credit for the discovery. He disproves the Drake legend concerning the introduction of the potato into Ireland and presents evidence to show that Raleigh may have been at least indirectly responsible for this event. T o the potato geneticist and others interested in botanical relationships, the author’s discussion of the species and the place of origin of the first introductions into Europe is of great interest. It is indicated that the first varieties to reach the British Isles belonged to the Solanum andigenurn species and not to S. tuberosum, as has been commonly supposed, and that they originated in the Andean highlands and not in southern Chile or in Chiloe Island, as the Russians claimed. The characteristics of other species, early culture, preservation, and use are discussed in considerable detail. The conhision and errors of early botanists, such as Gerard, are presented. The prejudices that attended the first introductions into European countries, originated by herbalists, medical men, and others, are described with documentary evidence to prove their existence. Many of these seem l’antastic, but no more absurd than some of the notions held at present. In spite of opposition and in response to a need the potato soon after its introduction assumed a place of importance in the economic and political life first in Ireland and later in England, Wales, and Scotland. The chapter on Potato Varieties, Past, Present, and Future, is of especial interest to potato geneticists and pathologists. Here the author gives the characteristics of many of the old varieties produced for the most part during the last half of the nineteenth century. They were bred by amateurs, “raiser-selectionists”, whose methods were empirical; but they produced a wide range of varieties, “exhibiting every shade of maturity and eating quality, combined with elegance of appearance and high yields”. Most of these varieties became infected with viruses, late blight (Phytophthora infestam), or wart disease (Synchytrizim endobioticurn). Early in the twentieth century potato breeding entered a new phase. Empirical methods were no longer adequate, and scientific methods were ushered in. The techniques and outstanding results are described in the account given of the efforts to produce varieties immune from or resistant to wart, late blight, and viruses. This chapter should be an inspiration and a guide to geneticists, pathologists, and agronomists, regardless of the crop with which they are working. Of chief interest to students of political science, sociology, and economics are the 20 chapters that give in detail the social, political, religious, and economic conditions and changes, chiefly in the British Isles from the sixteenth to the twentieth century. I t is indicated that the potato was both a blessing and a curse to Ireland; a blessing in that it provided the peasants the most food for the least labor of any of the crops; a curse in that the employers were quick to take advantage of the situation by paying lower wages because the workers had another means of subsistence. Then, too, the potato soon became the chief food among the peasants, and when crop failures resulted, as they did in the blight years of 1845 to 1847, a large number of people died of starvation and many others were reduced to dire poverty. The author emphasizes the important part of the potato in these calamities; but the impoverishing acts, the dispossessions, the raises in rents, and other harmful measures might have brought about similar calamities even if the potato had never reached Ireland, especially if the peasants were dependent on any one single food crop. One-crop dependence has always been a dangerous practice. The potato, because of its qualities of large production for little labor and excellent food value, may have contributed to Ireland’s woes; but that it should be blamed so heavily is questionable. A different picture is presented in the chapters that deal with England, Scotland, Wales, and Jersey. In these accounts it is clear that the potato has contributed much to the welfare and happiness of the people, as it has in many of the other countries of the world. The chapter on The Industrial Uses of the Potato by W. G. Burton shows that a high proportion of the world production possibly greater than that devoted to human consumption is used as feed for stock, and indicates some of the byproducts that have been made from the potato, such as starch, dextrins, acetone, alcohol, and alcoholic beverages, and its use as a starting point for the production of synthetic rubber. Salaman.stresses the value of the potato in wartime, stating that it was hardly second to wheat as a

The History and Social Influence of the Potato.

International Evaluation of Research and Doctoral Training at the University of Helsinki 2005-2010: RC-Specific Evaluation of SSA - Science of Sustainable Agriculture

Cold winters and geographic isolation have hitherto protected the Nordic countries from many plant pathogens and insect pests, leading to a comparatively low input of pesticides. The changing climate is projected to lead to a greater rise in temperature in this region, compared to the global mean. In Scandinavia, a milder and more humid climate implies extended growing seasons and possibilities to introduce new crops, but also opportunities for crop pests and pathogens to thrive in the absence of long cold periods. Increased temperatures, changed precipitation patterns and new cultivation practices may lead to a dramatic change in crop health. Examples of diseases and insect pest problems predicted to increase in incidence and severity due to global warming are discussed.

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The impact of global warming on plant diseases and insect vectors in Sweden

Viruses are among the most significant biotic constraints in potato production. In the century since the discovery of the first potato viruses we have learned more and more about these pathogens, and this has accelerated over the last decade with the advent of high-throughput sequencing in the study of plant virology. Most reviews of potato viruses have focused on temperate potato production systems of Europe and North America. However, potato production is rapidly expanding in tropical and subtropical agro-ecologies of the world in Asia and Africa, which present a unique set of problems for the crop and affect the way viruses can be managed. In this chapter we review the latest discoveries in potato virology as well as the changes in virus populations that have occurred over the last 50 years, with a particular focus on countries in the (sub-)tropics. We also review the different management approaches including use of resistance, seed systems, and cultural approaches that have been employed in different countries and reflect on what can be learnt from past research on potato viruses, and what can be expected in the future facing climate change.

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Viral diseases in potato

Potato mop-top virus (PMTV; genus Pomovirus; family Virgaviridae) is transmitted bythesoil-borneSpongosporasubterraneaf.sp.subterranea,aprotoctistthatcauses powdery scab on potato. PMTV is distributed widely in the potato growing areas in South and North America, Japan and northwestern Europe. This article reviews the current knowledge on detection, distribution and control of PMTV with focus on the Baltic Sea region. Since the 1980s, PMTV has caused great economic losses to potato production in the Nordic countries (Norway, Sweden, Denmark and Finland), but its occurrence in other countries of the Baltic Sea region remained unknown. To fill this knowledge gap, harmonised sampling and virus detection procedures including bioassays and serological and molecular methods were employed by 21 research institutions to detect PMTV in potato tubers and soil samples in 2005‐2008. Potato growing areas were widely contaminated with PMTV in the Nordic countries. Only the main seed potato production area in northern Sweden and the High Grade seed potato production zone in Finland were negative for PMTV. Intensive and

Detection, distribution and control of Potato mop‐top virus, a soil‐borne virus, in northern Europe

Nearly complete sequences of RNA-CP and 3'-proximal RNA-TGB were determined for 43 samples of potato mop-top virus (PMTV) originating from potato tubers and field soil from Sweden, Denmark and the USA. The results showed limited diversity and no strict geographical grouping, suggesting only a few original introductions of PMTV from the Andes. Two distinguishable types of RNA-CP and RNA-TGB were found in the samples, but no specific combination of them correlated with spraing symptoms in tubers. Lack of positive selection in the coding sequences indicates that there is no specific molecular adaptation of PMTV to new vectors or hosts.

/pdf/diversity-and-evolution-of-potato-mop-top-virus-38schr3v3m.pdf

Diversity and evolution of potato mop-top virus

Potato tuber necrosis in the form of spraing symptoms is caused by infection with Potato mop-top virus (PMTV) or Tobacco rattle virus (TRV); spraing has become more important in the Swedish potato crop production. In this study, the presence in Sweden of three potato-infecting viruses associated with necrotic symptoms in tubers was demonstrated: PMTV, TRV and Tobacco necrosis virus (TNV). This study shows that both PMTV and TRV are frequent in Swedish potato fields. PMTV was found in all Swedish counties, except the two most northern ones. TRV was present at several locations in southern and up to the central parts of Sweden. Both viruses were found further north than observed in earlier surveys. PMTV and TRV were analysed in tubers with spraing symptoms and it was not possible to decide visually if the symptoms were caused by either PMTV or TRV. Furthermore, a high occurrence of symptomless tuber infections was observed for several potato cultivars. A unique observation from this study was a mixed infection of both PMTV and TRV in tubers of cv. Berber, where no visual differences on symptom development were detectable for these tubers compared to single infections. During the survey, tubers of cv. Melody were found to display necrotic symptoms in the skin that are characteristic for the ABC disease. This suggested infection by TNV, which also could be confirmed.

Necrotic diseases caused by viruses in Swedish potato tubers

During the last decades, spraing disease caused by Potato mop-top virus (PMTV) has become a severe problem in the potato production throughout the Nordic countries. In this thesis, it was shown that PMTV is widely distributed throughout Sweden, Norway and Denmark, and has now become prevalent in the potato-production areas within these countries. In Sweden, PMTV was found to be present further north than observed in an earlier study. Compared to the Nordic countries, the occurrence of PMTV in Poland, the Baltic countries and northwestern Russia is still very limited. Molecular characterization and phylogenetic relationship analyses were carried out for 43 new PMTV sequences originating from potato tubers and field soil from Sweden, Denmark and the USA. The results showed a limited diversity of PMTV based on RNA-CP and RNA-TGB. No strict geographical grouping was obtained for isolates from Europe, Asia and North America indicating that PMTV has spread through infected seed tubers. Weeds, as alternative hosts of plants viruses and their vectors, are an important factor in the epidemiology of plant virus diseases. PMTV was detected in the roots of the weed Chenopodium album, which had been naturally infected with the virus in the field. C. album may together with weeds of the family Solanaceae be an important factor for maintaining PMTV in a field. Sequence analysis revealed a close relationship between the PMTV isolates from C. album and other characterised isolates suggesting that the same genotypes of PMTV are infecting potato and C. album.

The presence in Sweden of three other potato-infecting viruses associated with necrotic symptoms in tubers was demonstrated: Tobacco rattle virus (TRV), Tobacco necrosis virus (TNV) and Potato virus Y (PVY). TRV has become prevalent in potato fields located from southern and up to the central part of Sweden. Analyses of tubers with typical necrotic symptoms of the ABC disease confirmed infection with TNV. In addition, two different necrotic strains of PVY, PVYNTN and PVYNW, were detected in symptomatic potatoes. The presence of TNV and PVYNTN/PVYNW in potato plants was to our knowledge confirmed for the first time in Sweden.

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Ulrike Beuch

Papers

Detection, distribution and control of Potato mop‐top virus, a soil‐borne virus, in northern Europe

Diversity and evolution of potato mop-top virus

Necrotic diseases caused by viruses in Swedish potato tubers

Distribution and diversity of Potato mop-top virus in Sweden