Exotic Races Research Articles

Rapid emergency response to yellow rust epidemics caused by newly introduced lineages of Puccinia striiformis f. sp. tritici in Argentina

Yellow rust (YR), caused by Puccinia striiformis f. sp. tritici, is one of the most destructive diseases of wheat worldwide. In 2017, YR emerged in Argentina and spread quickly into three million hectares, causing damage at levels only seen during the severe epidemics during the late 1930s. This widespread occurrence coincided with reports of newly introduced exotic races into the country. Therefore, little was known about actual impact of the disease on yield, reaction of commercial wheat cultivars, efficacy and best timing for fungicide applications. This study addressed these fundamental questions to provide a quick response to the re-emergence of YR in Argentina. Thirty wheat cultivars (short and long cycle) were evaluated for their response to a PstS13 lineage of Puccinia striiformis f.sp. tritici. The efficacy of one or two fungicide applications for controlling YR was also assessed. Disease severity reached about 50% in the untreated plots at early crop growth stages. Disease and yield data analyses showed that one fungicide application provided effective YR control, but two applications further secured a significant relative increase in yield. Grain yield was negatively correlated with disease severity, and losses reached up to 4,700 kg/ha in the untreated control plots for several varieties. We provide new and important information on the control of and potential yield losses by a new exotic race of Puccinia striiformis f.sp. tritici introduced to South America.

Olfactory associative behavioral differences in three honey bee Apis mellifera L. races under the arid zone ecosystem of central Saudi Arabia.

Apis mellifera jemenitica is the indigenous race of honey bees in the Arabian Peninsula and is tolerant to local drought conditions. Experiments were undertaken to determine the differences in associative learning and memory of honey bee workers living in the arid zone of Saudi Arabia, utilizing the proboscis extension response (PER). These experiments were conducted on the indigenous race (A. m. jemenitica) along with two introduced European races (A. m. carnica and A. m. ligustica). The data revealed that A. m. jemenitica is amenable to PER conditioning and may be used in conditioning experiments within the olfactory behavioral paradigm. The results also demonstrated that the three races learn and retain information with different capacities relative to each other during the experimental time periods. Native Arabian bees (A. m. jemenitica) exhibited significantly lower PER percentage during second and third conditioning trials when compared to exotic races. Apis mellifera jemenitica also exhibited reduced memory retention at 2 h and 24 h when compared to A. m. carnica and A. m. ligustica. Therefore, the native Arabian bees were relatively slow learners with reduced memory retention compared to the other two races that showed similar learning and memory retention. Three or five conditioning trials and monthly weather conditions (October and December) had no significant effects on learning and memory in A. m. jemenitica. These results emphasized a novel line of research to explore the mechanism and differences in associative learning as well as other forms of learning throughout the year among bee races in the harsh arid conditions of Saudi Arabia. This is the first study in Saudi Arabia to demonstrate inter-race differences regarding olfactory associative learning between native Arabian bees and two introduced European honey bee races.

Genetic Diversity of the N’Dama Breed in Mali Using SSR Markers

The N'Dama race, trypanotolerant and well adapted to the climatic conditions of Mali, is threatened of disappearance by the introduction of other genes by means of the artificial insemination with the exotic races or zebus. In order to adopt preservation and conservation strategies, it is important to study the genetic characteristics of the race across the country. In this study, carried out on the race in its cradle (Yanfolila district, Sikasso region), the genetic diversity of 119 N'Dama race, from the Madina-Diassa Center for Preservation, Multiplication and Dissemination of Endemic Ruminant Livestock, was evaluated with 9 microsatellite markers (SSR). A total of 60 alleles were obtained. The number of alleles varied from 2 (BM 1824) to 12 (INRA 37) with an average of 6.67 per locus. The PIC ranked from 0.39 (BM 1824) to 0.9183 (INRA 37) with an average of 0.6605. Genetic diversity ranged from 0.4293 (BM 1824) to 0.9228 (INRA) with an average of 0.6908. The 119 N'Dama races were classified into two groups I and J according to the genetic similarities revealed by the 9 SSR markers using the UPGMA method. Group J was formed with the majority (85%) of individuals and composed of four (4) clusters J₁, J₂, J₃ and J₄. The 69 Nd, 71 Nd and 72 Nd individuals showed strong dissimilar compared to other individuals in group J and formed cluster J₁. Moreover, one cluster, with 15% of individuals, was belonged to Group I. The results of this study will contribute to the application of molecular tools and strengthen strategies for conservation, preservation and genetic improvement of the N’Dama race in Mali.

Planting exotic relatives has increased the threat posed by Dothistroma septosporum to the Caledonian pine populations of Scotland.

To manage emerging forest diseases and prevent their occurrence in the future, it is essential to determine the origin(s) of the pathogens involved and identify the management practices that have ultimately caused disease problems. One such practice is the widespread planting of exotic tree species within the range of related native taxa. This can lead to emerging forest disease both by facilitating introduction of exotic pathogens and by providing susceptible hosts on which epidemics of native pathogens can develop. We used microsatellite markers to determine the origins of the pathogen Dothistroma septosporum responsible for the current outbreak of Dothistroma needle blight (DNB) on native Caledonian Scots pine (Pinus sylvestris) populations in Scotland and evaluated the role played by widespread planting of two exotic pine species in the development of the disease outbreak. We distinguished three races of D. septosporum in Scotland, one of low genetic diversity associated with introduced lodgepole pine (Pinus contorta), one of high diversity probably derived from the DNB epidemic on introduced Corsican pine (Pinus nigra subsp. laricio) in England and a third of intermediate diversity apparently endemic on Caledonian Scots pine. These races differed for both growth rate and exudate production in culture. Planting of exotic pine stands in the UK appears to have facilitated the introduction of two exotic races of D. septosporum into Scotland which now pose a threat to native Caledonian pines both directly and through potential hybridization and introgression with the endemic race. Our results indicate that both removal of exotic species from the vicinity of Caledonian pine populations and restriction of movement of planting material are required to minimize the impact of the current DNB outbreak. They also demonstrate that planting exotic species that are related to native species reduces rather than enhances the resilience of forests to pathogens.

Rapid Phenotyping Adult Plant Resistance to Stem Rust in Wheat Grown under Controlled Conditions.

Stem rust (SR) or black rust caused by Puccinia graminis f. sp. tritici is one of the most common diseases of wheat (Triticum aestivum L.) crops globally. Among the various control measures, the most efficient and sustainable approach is the deployment of genetically resistant cultivars. Traditionally, wheat breeding programs deployed genetic resistance in cultivars, but unknowingly this is often underpinned by a single seedling resistance gene, which is readily overcome by the pathogen. Nowadays, adult plant resistance (APR) is a widely adopted form of rust resistance because more durable mechanisms often underpin it. However, only a handful of SR APR genes are available, so breeders currently strive to combine seedling and APR genes. Phenotyping adult wheat plants for resistance to SR typically involves evaluation in the field. But establishing a rust nursery can be challenging, and screening is limited to once a year. This slows down research efforts to isolate new APR genes and breeding of genetically resistant cultivars.In this study, we report a protocol for rapid evaluation of adult wheat plants for resistance to stem rust. We demonstrate the technique by evaluating apanel of 16 wheat genotypes consisting of near isogenic lines (NILs) for known Sr genes (i.e., Sr2, Sr33, Sr45, Sr50, Sr55, Sr57, and Sr58) and three landraces carrying uncharacterized APR from the N. I. Vavilov Institute of Plant Genetic Resources (VIR). The method can be completed in just 10weeks and involves two inoculations: first conducted at seedling stage and a second at the adult stage (using the same plants). The technique can detect APR, such as that conferred by APR gene Sr2, along with pseudo-black chaff (the morphological marker). Phenotyping can be conducted throughout the year, and is fast and resource efficient. Further, the phenotyping method can be applied to screen breeding populations or germplasm accessions using local or exotic races of SR.

Replacement of the European wheat yellow rust population by new races from the centre of diversity in the near‐Himalayan region

Isolates of recently spreading races of yellow rust from wheat and triticale in Europe were analysed using virulence phenotypic data of 2605 isolates sampled in 12 countries between 2000 and 2014. A subset of 239 isolates was investigated by microsatellite markers. At least three races of non‐European origin, termed ‘Warrior’, ‘Kranich’ and ‘Triticale aggressive’, were identified in the post‐2011 population. The Warrior race was already present in high frequencies in the first year of detection in most European countries and to a large extent it replaced the pre‐2011 European population. In contrast, the two other exotic races were localized to certain regions and/or crop type. The presence already of at least six multilocus genotypes of the Warrior race and five genotypes of the Kranich race in the first year of detection and across large areas is consistent with a hypothesis of aerial spread from genetically diverse source populations. A comparison with reference isolates sampled from six continents suggested that the Warrior and Kranich races originated from sexually recombining populations in the centre of diversity of the yellow rust fungus in the near‐Himalayan region of Asia. However, the Triticale aggressive race was most similar to populations in the Middle East/Central Asia. The study illustrated the potential role of sexual Puccinia striiformis populations as a reservoir for new races replacing distant clonal populations.

Volatile fraction of DOP “Castelo Branco” cheese: Influence of breed

“Castelo Branco” cheese is a Portuguese DOP cheese made from raw ewe’s milk coagulated with Cynara cardunculus, ripened for at least 40 days. “Merino da Beira Baixa” pure race is frequently used to produce milk for this cheese, however, exotic races such as Assaf and crusade of these two races are also used. The aim of this work has been to compare the volatile profile and sensory characteristics of DOP “Castelo Branco” cheeses manufactured during winter season with milk of breeds from Merino, Assaf and crusade of these two races and identify volatile compounds that can distinguish these cheeses. Volatile compounds profile was assayed by SPME–GC–MS. A total of 67 volatile compounds were separated and identified. The volatile profiles of the three types of cheeses differed significantly. Descriptive analysis and triangle tests confirmed that these cheeses presented significantly different sensory characteristics. Discriminant analysis showed that specific volatile components seemed to distinguish specific cheeses.

Soroprevalência da infecção pelo vírus da artrite-encefalite caprina (caev) no rebanho de caprinos leiteiros da região da Grande Fortaleza, Ceará, Brasil

Foi realizada uma pesquisa sorológica, com base no teste de imunodifusão em ágar gel (AGID) com antígeno (p28) do vírus Maedi/Visna, para estimar a soroprevalência da infecção pelo vírus da Artrite-Encefalite Caprina (CAEV) na população de caprinos leiteiros da região da Grande Fortaleza, Ceará. O estudo abrangeu um total de oito criatórios. dos quais cinco praticam o manejo intensivo e três o manejo semi-intensivo. A população estudada é composta, por animais puros de raças exóticas como a Saanen, Parda Alpina, Anglonubiana e Toggenburg, por animais Meio Sangue e alguns sem raça definida (SRD). Foi realizado exame clinico e coleta de amostra de soro em 248 caprinos, bem como a aplicação de questinonário epidemiológico. A análise dos dados revelou uma soroprevalência de 40,73% (101/248). As amostras soropositivas foram todas provenientes das propriedades com manejo intensivo (5/8). A distribuição da soroprevalência em cada um destes criatórios foi 61% (54/89), 74,28% (26/35), 61,11% (11/18), 11,36% (5/44) e 75% (6/8). Diferença significativa (P<0,05) foi observada quanto a soroprevalência entre os grupos genéticos de animais puros, meio sangue e SRD que apresentaram 66% (80/122), 31% (19/61) e 3% (2/65) respectivamente. Não foram observadas diferenças significativas (P>0,05) quanto aos falares idade e sexo dos animais estudados.

The allotetraploidization of maize

Allotetraploidization is the creation of artificial allotetraploids. Allotetraploidization of maize can be achieved by restructuring a maize genome so that its chromosomes will not pair with those of the normal maize genome. The restructuring can be done by concentrating induced or naturally occurring visible and cryptic chromosome aberrations and qualitatively different genetic material into a single line by a recurrent selection type of breeding program. The basis of allotetraploidization is the presence of differential pairing affinity between normal and restructured chromosomes. Experiments demonstrate that differential pairing affinity factors occur naturally in exotic races and in standard corn belt inbred lines and that they may be readily induced by X-irradiation and chemical mutagens.

Ecology of Exotic Races of Maize. I. Leaf Number and Tillering of 16 Races Under Four Temperatures and Two Photoperiods1

Use of photosensitive types of maize (Zea mays L.), such as the approximately 250 Latin American races, is severely limited by late flowering and excessive growth under field conditions encountered in latitudes exceeding 30°%. It is known that both shorter day lengths and lower temperatures tend to reduce excessive growth by initiating flowering at an earlier stage of development. The joint effects and possible interactions of such treatments apparently have not been previously studied. Sixteen races of maize, adapted to varying altitudes, growing conditions, and latitudes, were grown in the North Carolina State University Phytotron at day/night temperatures ranging from 10/6 to 34/30 C under short (9‐hr) days. The same races were grown under long days at temperatures ranging from 18/14 to 34/30 C. The photoperiod difference was much more effective than temperature in decreasing leaf numbers, and while the interaction of photoperiods and temperatures was significant, it was relatively small. Lowest leaf numbers were generally obtained under the 18/14 C 9‐hour day regime. Since these numbers ranged as high as 20 leaves per plant, additional reduction, perhaps by using shorter days with temperatures in the range of 14 to 22 C, would be desirable.In contrast, temperature rather than photoperiod length is more effective in altering the numbers of tillers per plant. With a single exception, the races that tillered did so more profusely at the lower temperatures.

CYTOGENETIC STUDIES OF DEFICIENT‐DUPLICATE CHROMOSOMES DERIVED FROM INVERSION HETEROZYGOTES IN MAIZE

THE PRESENT INVESTIGATION was the outgrowth of studies of the chromosome homology of maize from Central and South America. Strains of maize from Latin America exhibit an extraordinarily wide range of phenotypic appearance owing to genic differences. Since many of these strains presumably have been isolated for centuries, it was thought possible that the genic diversity had been accompanied by changes in chromosomal structure. Cooper and Brink (1937) found no evidence of reciprocal translocations in their study of chromosome homology in 55 strains of maize from Latin America but their method of analysis would not permit the detection of inversions. Inasmuch as inversions in Drosophila populations are of frequent occurrence (Patterson and Stone, 1952) while reciprocal translocations are rarely encountered, it seemed desirable to test exotic races of maize for the presence of inverted segments. F1 seed from crosses of two genetic testers with 90 different races of Latin American origin was obtained through the courtesy of Dr. P. C. Mangelsdorf. Eighty-five of these hybrid combinations involved a Pr-tester and five, a Tu stock. Microsporocytes for cytological examination were collected from a number of plants of each F1 family. Pollen samples were obtained for all of the F1 individuals. Plants heterozygous for a single reciprocal translocation usually have 50 per cent of aborted pollen and ovules while plants heterozygous for inversions produce varying amounts of aborted grains depending on the frequency of crossing over within the inverted segment. The absence of any considerable amount of aborted pollen indicated that all of the 85 progenies involving the Pr-tester possessed chromosomes with no major structural differences. In two of the five families where the Tu line was used, all of the plants had approximately 20 per cent aborted pollen while in two other families one half of the plants had a comparable degree of pollen abortion and the other half had all normal grains. The fifth family consisted only of plants with all normal pollen. When the cytological material from the four families with aborted pollen was examined it was found that all plants with aborted grains were heterozygous for a paracentric inversion in chromosome 3. There was no evidence of reciprocal translocation in any of the 90 exotic races nor was there any indication of inversions. The inversion found was obviously one which came from the Tu stock where it was segregating since some plants were homozygous normal, others homozygous for the inversion and some were heterozygous. It should be recognized

NOTES ON THE HANDS AND FEET OF AMERICAN NATIVES

THE present article was originally intended to form part of a series of papers which I published, and which are further going to appear in L'Anthropologie under the general title of M6langes anthropologiques. The great difficulties and unavoidable tardiness of publication of these memoirs, however, in consequence of the war, induces me to present the following article to the American Anthropologist, although in a somewhat different form than first intended, and as I did previously with another contribution in relation to the M6langes. 1 Herewith the work, of which the first number appeared in 1913, comes at last to an end. The following data pertaining to hands and feet of North and South American Indians, Carbugres and Bush Negroes, both natives of Surinam, are based upon my own observations and measurements, mostly made and taken in the field, mainly in the years 1883, 1885-86, and 1888. With the exception of a few figures concerning the stature and the indices of hands and feet, all these data are here published for the first time. I am well aware of the scantiness of my material as it is given here, but it should be studied in connection with the other somatological data which, as I said before, have been or are to be published elsewhere and of which it forms the necessary supplement.2 Besides measurements and observations on hands and feet of exotic races, as treated in the present paper, as far as I know, are comparatively