Wild Gene Pool Research Articles

The wild genetic resources of cultivated lettuce (Lactuca sativa L.)

Seven wild Lactuca species: L. serriola L., L. aculeata Boiss. & Ky., L. scarioloides Boiss., L. azerbaijanica Rech., L. georgica Grossh., L. dregeana DC. and L. altaica Fisch. & C.A. Mey., are taxonomically closely related to the cultivated lettuce. Together with L. sativa they form a distinct natural group. Only scanty information is available on genetic affinities among the various members of this group. However, the combined taxonomic and genetic evidence indicates that all these 7 wild lettuces are very likely interfertile (or largely interfertile) with the crop, and constitute its primary wild gene pool. Also the taxonomically more distant L. saligna L. is partly cross-fertile with the crop.

Deforestation and Shrinking Crop Gene-pools in Amazonia

Deforestation in Amazonia is eliminating wild genepools of many crop-plants. Wild or spontaneous populations of at least 50 perennial crops are at risk, including the Rubber tree and Cacao, as well as several crops emerging from relative obscurity, such as Peach-palm (which is now being planted extensively for palmito production), Annatto (which produces a natural red dye), and Brazil-nut.

Survival Rates of Hand-Reared Mallards Released on 2 Private Farms

I derived survival rates of hand-reared mallards (Anas platyrhynchos) released on 2 private farms in Maryland using stochastic models. Survival rates of summer-banded young for the first hunting season to the time of postseason banding in February averaged 0.29 and 0.47 for males and females, respectively. Survival rates of adults banded postseason generally were lower (f difference = -0.18, P < 0.02) than those of wild mallards banded postseason in Maryland. Survival rates of hand-reared adult males averaged 0.35; female survival rates were 0.27 at Remington Farms and 0.55 at Money Point Farm. Survival rates of handreared mallards were lower and nonhunting mortality rates higher than those of wild mallards. J. WILDL. MANAGE. 53(1):114-118 Releasing hand-reared mallards is controversial in the Atlantic Flyway (Atl. Waterfowl Counc., unpubl. min. of annu. meetings, 1979, 1980). Released birds may have traits that lead to low survival in the wild and they may contaminate the wild gene pool (Banks 1972). Previous estimates of survival rates for hand-reared mallards used early unsophisticated methods based on invalid assumptions (Brownie et al. 1985:8). My objective was to estimate survival rates, derived from stochastic models, of handreared mallards released on 2 private farms in Maryland. I thank A. G. Decker, Jr. for allowing me to use hunting and banding records, and his staff for assisting with bird banding. J. D. Nichols and the U.S. Fish and Wildlife Service's (USFWS) Bird Banding Laboratory assisted with compilation and analysis of data. Remington Arms Company, Incorporated, funded the study. STUDY AREA AND METHODS Mallard releases were made on Money Point and Remington F4rms located on Maryland's Eastern Shore. Money Point was a 95-ha grain farm, located in Cecil County on the north shore of the Sassafras River. Remington Farms was a 1,330-ha grain farm and wildlife management and demonstration area, located in Kent County, and bordered an estuarine creek of the Chester River. Money Point Farm released about 1,000 mallards annually. Each spring 80 carry-over second-year females and 20 males were selected as breeders. Ducklings were raised in a brooder house for 10 weeks, then released (about midJul) in groups on 3 ponds and the creek shore. Mallards were fed until 10 days before the start of the hunting season. Remington Farms released about 5,700 mallards annually. One-day-

Genetic diversity and environmental associations of wild emmer wheat, in Turkey

Genetic diversity within and between Turkish populations of the wild progenitor of wheats, tetraploid wild emmer wheat, Triticum turgidum var. dicoccoides, was studied electrophoretically. Forty-eight enzyme loci were assayed in 157 individual plants representing four populations of T. t. dicoccoides, across a transect of 90 km in Turkish Kurdistan. The following results were indicated: (i) T. t. dicoccoides in Turkey comprises medium levels of allozyme diversity. Out of 48 putative loci 19 (40 per cent) were polymorphic and the level of genetic diversity was medium He=0·057. (ii) Altogether we scored 72 alleles in the 48 loci. (iii) The population genetics structure of T. t. dicoccoides in Turkey, similar to that in Israel (Nevo et al., 1982), displayed an ecological-genetic, semi-isolated, “archipelego”. Thirteen of the 24 variant alleles (or 54 per cent) were localized. (iv) The mean genetic distance between populations was D=0·046, range 0·019–0·082. (v) About 86 per cent of the plants (101 out of 117) analyzed by discriminant analysis were correctly classified in their population spaces. (vi) Genetic diversity, He, and some representative allele frequencies were significantly explained by two variable combinations of water, temperature or geographical factors. (vii) 63 per cent of the allozyme variation was within and 37 per cent was between populations. (viii) Significant gametic phase disequilibria abound, displaying allele association at the two-locus level. (ix) Strong allele associations occur at the multilocus level at the megapopulation and at each of the 4 populations. On the average, the megapopulation was 71 per cent higher in the number of expected heterozygous loci, K, than that expected under random associations; the range between populations was X(2) = 29–125 per cent.These results suggest that (i) climatic selection plays an important role in genetic differentiation of wild emmer populations, and (ii) the wild gene pool comprises significant genetic resources for utilization in wheat improvement.

International prospects for cooperation in crop research

Agricultural research is increasingly a global effort. No country can remain isolated in agricultural research without damaging its capacity to respond to challenges to agricultural productivity. In this paper, we explore the role of botany in the international effort to raise and stabilize farm yields. Given the importance of wild species in crop breeding and the increasing use of wild species to upgrade crops, the value of systematics is underlined. The contribution of plant physiology is also discussed, particularly with reference to mechanisms of resistance to pests and diseases and tolerance to adverse soils and climates. The crucial role of ecological studies based on field work is also underscored, particularly as it applies to wild plants and natural genepools, as well as crop protection. The necessity for continued support of botanical studies and gardens is emphasized in the light of the global effort to conserve and utilize crop genetic diversity. Finally, we examine some developments in mycology and biotechnology that have implications for agriculture and pinpoint opportunities for increased collaboration between botanists and agricultural scientists.

Genetic diversity and environmental associations of wild barley,Hordeum spontaneum (Poaceae), in Iran

Genetic diversity and structure of populations of the wild progenitor of barleyHordeum spontaneum in Iran was studied by electrophoretically discernible allozymic variation in proteins encoded by 30 gene loci in 509 individuals representing 13 populations of wild barley. The results indicate that: a)Hordeum spontaneum in Iran is extremely rich genetically but, because of predominant self-pollination, the variation is carried primarily by different homozygotes in the population. Thus, genetic indices of polymorphismP-1% = 0.375, range = 0.267−0.500, and of genetic diversity,He = 0.134, range = 0.069−0.198, are very high. b) Genetic differentiation of populations includes clinal, regional and local patterns, sometimes displaying sharp geographic differentiation over short distances. The average relative differentiation among populations isGst = 0.28, range = 0.02−0.61. c) A substantial portion of the patterns of allozyme variation in the wild gene pool is significanctly correlated with the environment and is predictable ecologically, chiefly by combinations of temperature and humidity variables. d) The natural populations studied, on the average, are more variable than two composite crosses, and more variable than indigenous land races of cultivated barely,Hordeum vulgare, in Iran. — The spatial patterns and environmental correlates and predictors of genetic variation ofH. spontaneum in Iran indicate that genetic variation in wild barley populations is not only rich but also at least partly adaptive. Therefore, a much fuller exploitation of these genetic resources by breeding for disease resistance and economically important agronomic traits is warranted.

Hybridization in the genus Lens by means of embryo culture

The cultivated lentil L. culinaris and the wild lentil L. ervoides are reproductively isolated from one another due to their hybrid embryo breakdowns. Using embryo culture, vegetatively normal hybrids were obtained. One specific hybrid, heterozygous for a reciprocal translocation, had about 50% gamete viability and produced aborted and viable embryos in a 1∶1 ratio. In the F2, vegetatively normal and highly fertile plants were selected. With the aid of embryo culture techniques, L. ervoides can be included in the wild gene pool of the cultivated lentil.

Genetic diversity and environmental associations of wild wheat, Triticum dicoccoides, in Israel

Allozyme variation in the tetraploid wild progenitor of wheat, Triticum dicoccoides, was studied for the proteins encoded by about 50 gene loci in 457 individuals representing 12 populations from Israel. Six spikelet morphological traits were measured in the same populations. The results indicate that: (a) 16 loci (= 32%) were monomorphic in all 12 populations, 15 loci (= 30%) were locally polymorphic, and 19 loci (= 38%) were regionally polymorphic. All polymorphic loci (but one) displayed high levels of polymorphism (≧ 10%). In Israel, the proportion of polymorphic loci per population, P, in wild wheat averaged 0.25 (range, 0.16-0.38), and the genetic diversity index, He averaged 0.07, (range, 0.03 - 0.12). (b) Altogether there were 110 alleles at the 50 putative loci tested (c) Genetic differentiation of populations included regional and local patterns: (i) The coefficients of genetic distance between populations were high (mean D = 0.10 range, 0.02 - 0.25), and indicated sharp genetic differentiation over short distances, (ii) Common (≧ 10%) but sporadic and localized alleles were frequent (76%), and (iii) Rare alleles were few (only 5 alleles). (d) The patterns of allozyme and spikelet variation in the wild gene pool were significantly correlated with, and partly predictable by, water factors, including those of precipitation, evaporation, and relative humidity as well as of soil type, (e) All six spikelet characters showed statistically significant variation among localities and (f) Allozymic variation was correlated with spikelet variation.These results suggest in T. dicoccoides: (i) the operation of natural selection in population genetic structure, (ii) local adaptive genetic differentiation caused by diversifying selection through climate and soil, and (iii) the guidelines for sampling these resources for use in wheat breeding programs.

People

Despite the importance of the reindeer husbandry in the subsistence of many northern cultures the origin and spread of domestic reindeer is still highly debated. Recent analyses of mitochondrial DNA in reindeer herds across Eurasia revealed distinct geographic structures of domestic reindeer in Fennoscandia and Russia, pointing towards independent origins of domestic reindeer in these areas. A high degree of haplotype sharing between the extant wild reindeer population in the Hardangervidda mountain region in southern Norway and the domestic herds in Fennoscandia indicate that this population could have contributed in the early domestication or augmented the domestic population. However, genetic analyses of excavated reindeer remains from the early medieval period from the Hardangervidda region revealed no haplotype sharing with extant domestic reindeer, demonstrating that reindeer from Hardangervidda did not contribute in the early domestication process in Fennoscandia. The substantial temporal genetic alteration observed in this population is related to introgression of domestic reindeer into the wild gene pool in the 19th century during periods when reindeer husbandry was practiced in this mountain region.

The origin of lentil and its wild genepool

Following hybridization experiments and cytogenetic analysis of interspecific hybrids three chromosome interchanges were found between the cultivated lentil L. culinaris and L. nigricans, and only one between the cultivated species and L. orientalis. This indicates that the latter species is more likely to be wild progenitor of lentil. The partial fertility of the interspecific hybrids indicate further that both L. nigricans and L. orientalis should be included in the wild genepool of lentil, and their variation can be exploited by relatively simple hybridization techniques. The wild lentils L. orientalis and L. nigricans are morphologically very similar but reproductively strongly isolated from one another by the albino seedling of their hybrids. It has been suggested that the populations of L. orientalis that gave rise to the cultivated lentil still possess a similar chromosome arrangement as in L. culinaris and are also capable of forming normal hybrids with L. nigricans. According to these considerations it is unlikely that lentil originated from populations at the south western corner of the distribution area of L. orientalis.

Beginnings of Fruit Growing in the Old World

The article reviews the available information on the start of fruit tree cultivation in the Old World. On the basis of (i) evaluation of the available archeological remains and (ii) examination of the wild relatives of the cultivated crops, it was concluded that olive, grape, date, and fig were the first important horticultural additions to the Mediterranean grain agriculture. They were most likely domesticated in the Near East in protohistoric time (fourth and third millennia B.C.) and they emerge as important food elements in the early Bronze Age. Domestication of all four fruit trees was based on a shift from sexual reproduction (in the wild) to vegetative propagation of clones (under domestication). Olive, grape, date, and fig can be vegetatively propagated by simple techniques (cuttings, basal knobs, suckers) and were thus preadapted for domestication early in the development of agriculture. The shift to clonal propagation placed serious limitations on selection and on fruit set under cultivation. We have examined the consequences of this shift in terms of the genetic makeup of the cultivars and traced the various countermeasures that evolved to ensure fruit set. Finally, it was pointed out that in each of these classic fruit trees we are confronted with a variable complex of genuinely wild types, secondary weedy derivatives and feral plants, and groups of the domesticated clones, which are all interfertile and interconnected by occasional hybridization. It was concluded that introgression from the diversified wild gene pool facilitated the rapid buildup of variation in the domesticated crops.