Sources of Resistance to Whitefly (Bemisia spp.) in Wild Populations of Solanum lycopersicum var. Cerasiforme (Dunal) Spooner G.J. Anderson et R.K. Jansen in Northwestern Mexico

Genetic variability of wild populations, closely related to domesticated species, constitute important genetic resources for plant breeding programs. In this paper, we analysed the variation of eight wild populations of Solanum lycopersicum var. cerasiforme in a common garden experiment for levels of plant infestation by whitefly, leaf trichome density as a defensive character preventing infestation by whitefly, and the effect of whitefly incidence into vegetative and reproductive plant characters. Number of adults of whitefly was recorded in the eight wild populations of S. lycopersicum var. cerasiforme, one population of the wild species S. habrochaites (C-360), and one of a cultivated variety of S. lycopersicum (Rio Grande). There were significant differences among the wild populations of S. lycopersicum var. cerasiforme in the average level of whitefly incidence and trichome density. Cultivated tomatoes had the higher incidence of whiteflies ( = 7.50 ± 0.14) followed by plants of S. lycopersicum var. cerasiforme ( = 2.02 ± 0.92) and plants of S. habrochaites with the lowest incidence ( = 0.36 ± 0.35). Whitefly incidence was negatively correlated with trichome density (r = − 0.38, p < 0.0001), suggesting that trichomes deter or limit the establishment of whiteflies. Additionally, a significant negative effect of whitefly incidence along the growing season upon plant growth rate (number of branches and height) and fruit production was detected.     

First sources of resistance to Sitona weevil (Sitona crinitus Herbst) in wild Lens species

Lentil is one of the important cool-season food legumes grown in many countries in the Mediterranean region. But a substantial yield loss is observed every year due to various biotic stresses. The Sitona weevil (Sitona crinitus Herbst) is a major insect pest limiting lentil productivity mainly in the countries of West Asia and North Africa region. The adult insects feed on the leaflets at seedling stage, and the plant suffers due to reduced photosynthesis. The larvae feed on the root systems and on the nodules, thus decreasing the ability of the plant to fix atmospheric nitrogen. Since sources of resistance to this pest in the cultivated lentil Lens culinaris Medikus subsp. culinaris are lacking, we searched for resistant sources in a collection of wild Lens species available in the ICARDA Gene Bank. We screened 315 accessions of wild lentil covering all known species/sub-species based on nodule damage at ICARDA’s main experimental station (Tel Hadya, Aleppo), a hot-spot for the pest in the region. Large variation was observed in the percent nodule damage among accessions across species. Eight accessions, ILWL 110, ILWL 136, ILWL 166, ILWL 203, ILWL 207, ILWL 245, ILWL 254 and ILWL 258 were identified as resistant, with ≤10% nodule damage, compared to >56% damage recorded on the cultivated lentil. This is the first report of resistance against Sitona weevil in lentil. One resistant accession ILWL 245 belongs to the species L. culinaris Medikus subsp. orientalis (Boiss.) Ponert, progenitor of the cultivated lentil, which is crossable with the cultivated lentil. This line is being used to introgress resistance genes to cultivated lentil and to understand the inheritance of Sitona weevil resistance.     

Evaluation of Wild Lens Taxa for Agro-Morphological Traits, Fungal Diseases and Moisture Stress in North Western Indian Hills

Exploitation of wild gene pool for breeding is a common practice in an increasing number of cultivated plants. The cultivated lentil could not attain the substantial improvement in the yield potential due to loss of genes for higher productivity and lack of resistance against biotic and abiotic stresses. The absence of evaluation data of wild lentils for characters of economic importance, besides biotic and abiotic stresses, is one of the constraints in their use in lentil breeding programme. In the present study, 70 wild accessions from four wild Lens subsp./sp. (L. culinaris subsp. orientalis, L. odomensis, L. ervoides and L. nigricans) along with 3 checks (Precoz, PL-406 and PL-639) were evaluated for phenological and agro-morphological characters, for their reaction to three fungal diseases (wilt, powdery mildew and rust) and screened for tolerance to moisture stress. The wild accessions showed higher performance for branches/plant as compared to cultivated genotypes. Similarly, a few accessions of L. culinaris subsp. orientalis were earlier to flower and had higher seeds and seed yield/plant as compared to cultivated lentil. However, some were comparable with cultivated genotypes for flowers/peduncle, peduncle length and plant height. The mean performance for flowers per peduncle, leaflets per leaf, plant height, seeds and seed yield per plant increased, while decreased for days to flowering and maturity, and branches per plant during the evolution of cultivated lentil from the wild Lens taxa. Of Lens taxa, L. nigricans had the maximum resistant accessions for biotic and tolerance to abiotic stresses. The valuable variation existing among wild accessions can be exploited following introgression with cultivated lentils. It will help in the flow of useful genes from wild to cultivated lentil for generating wide spectrum of variability and its subsequent use in genetic restructuring of lentil.     

Assessment of Genetic Relationships between Wild and Cultivated Mulberry (Morus) Species using PCR Based Markers

In order to formulate appropriate strategies for the conservation and utilization of the wild mulberry genetic resources available in India, a study was undertaken with 20 mulberry genotypes from the four different species. Seventeen intersimple sequence repeat primers were used to generate a total of 114 markers, of which 98 (85.96%) were polymorphic. Seven unique bands for Morus serrata Roxb. and one for both M. serrata Roxb. and Morus macroura Miq. were identified, of which one fragment has been sequenced and deposited in the EMBL-GeneBank (AJ-585512). The genetic dissimilarity coefficients varied from 0.078 to 0.530 among these genotypes and from 0.168 to 0.465 among the species. The dendrograms realized from these markers clustered the genotypes into three groups. The outermost group was M. serrata Roxb., which was followed by the group of M. macroura Miq. and the innermost group contained genotypes of Morus indica L. and Morus alba L. This intermixing of genotypes of M. indica and M. alba supports the view that M. indica is merely a synonym of M. alba. Distribution of the genotypes on a two-dimensional figure upon multidimensional scaling with ALSCAL program, further, confirmed the genetic divergence between the cultivated and wild mulberry groups. On the basis of the results a few potential wild mulberry genotypes were identified for its conservation and utilization in breeding programs to confer the stress tolerance to the cultivated varieties of mulberry.     

Perennial Wild Relatives of Chickpea as Potential Sources of Resistance to Helicoverpa armigera

The legume pod borer, Helicoverpa armigera (Hübn.), is one of the major constraints to chickpea production, and host plant resistance is an important component for the management of this pest. The levels of resistance in the cultivated chickpea are low to moderate, and therefore, we evaluated 17 accessions of perennial Cicer along with three cultivated chickpea genotypes for resistance to H. armigera. There was a significant reduction in both leaf feeding and larval weights when the larvae were fed on the leaves of Cicer microphyllum Benth. accessions ICC 17146, ICC 17236, ICC 17240, and ICC 17248. Relative resistance index based on leaf feeding, larval survival, and larval weight indicated that C. microphyllum accessions ICC 17146, ICC 17236, ICC 17234, ICC 17240, ICC 17243, and ICC 17248 were highly resistant to H. armigera. Under natural infestation, accessions belonging to C. microphyllum, C. canariense Santos Guerra et Lewis, and C. macracanthum M. Pop suffered a damage rating of <2.0 compared to 4.0 in C. judaicum Boiss. accession ICC 17148 (annual species) and 8.5–9.0 in the cultivated chickpeas (1 = <10% leaf area damaged, and, 9 = >80% leaf area damaged). There was considerable diversity in the accessions belonging to perennial wild species of chickpea, and these can be exploited to increase the levels and diversify the basis of resistance to H. armigera in the cultivated chickpea.     

Quantitative Trait Loci for Seed Dormancy in Wild Barley (Hordeum spontaneum C. Koch)

A quantitative trait locus analysis was carried out to unravel the genetic basis of dormancy in wild barley (Hordeum spontaneum) from Israel. Two accessions, Ashkelon and Mehola, from divergent environments were crossed to produce a mapping population. A linkage map was produced from the F₂ population, and F₄ seeds were used for germination experiments. Five quantitative trait loci (QTL) were detected for dormancy across the different germination experiments. These QTL were found on chromosomes 1, 2, 5, 6 and 7. The variation explained by each QTL varied between 8 and 25%. Ashkelon alleles increased the germination except for the QTL on chromosome 5. Three out of these five QTL co-locate with QTL found earlier in cultivated barley crosses, although this does not necessarily imply that they would be the same loci. The level of dormancy is much higher in wild barley than in cultivated barley and wild barley may have alleles that have not yet been utilised in breeding for optimally dormant barley.     

Karyotypic Studies on Some Cultivated and Wild Species of Chenopodium (Chenopodiaceae)

Detailed karyotypic studies have been done in 20 wild and cultivated taxa of Chenopodium, which belong to three ploidy levels 2x, 4x and 6x. C. quinoa (4x) shows minor but consistent differences in the arm ratio of various chromosomes within the complements of different accessions. The chromosomes can be arranged in 18 pairs that suggest allotetraploid nature. The karyotype of C. berlandieri subsp. nuttalliae (4x) is basically similar to that of C. quinoa. C. bushianum (6x) is distinctly different from the above two species in showing highest ratio between longest and shortest chromosomes. C. album complex is characterized by consisting of 2x, 4x and 6x cytotypes. Marked karyotypic differentiation is seen even among various 2x accessions. The 4x cytotype has a more asymmetrical karyotype as compared with 2x and 6x cytotypes. The karyotypic differences are also apparent between two 6x cytotypes studied. C. strictum (6x) and C. giganteum (6x) show close similarity to 6x types of C. album.     

Searching for New Sources of Pink Stem Borer Resistance in Maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.)

The pink stem borer (Sesamia nonagrioides Lef.) is the main corn (Zea mays L.) pest in the Mediterranean area. Although, screening for resistance to this pest has been successful, the level of resistance shown by the most resistant varieties is not high. The objectives of the present work were: (i) the evaluation for pink stem borer resistance of the nontested inbred lines, field and popcorn materials, from the collection maintained at the Misión Biológica de Galicia and (ii) the study of the performance, under pink stem borer infestation, of inbreds selected for resistance to pink stem borer in hybrid combination. Forty four inbred lines nontested yet for resistant to pink stem borer along with five inbred lines previously reported as resistant to stem and ear attack, were evaluated in 2002 and 2003. In adjacent experiments, hybrids EP79× W552, EP77× B93, and A661× EP42 were tested along with a resistant hybrid, MEB531-Bt, and a susceptible hybrid, INRA 260. New sources of resistance to pink stem borer have been detected among inbred lines improving the level of resistance presented by previously tested inbreds. Some of these lines were successfully developed by pedigree selection for resistance to pink stem borer.     

Evaluation of Genetic Diversity of Wild Rice (Oryza rufipogon Griff.) in Myanmar using Simple Sequence Repeats (SSRs)

As a part of an in situ survey of wild rice (Oryza rufipogon Griff.) in Myanmar (Burma), 16 strains of wild rice were collected, and analyzed for allelic diversity over 74 loci with simple sequence repeat (SSR) markers to obtain a basic information for their conservation. Three each of indica and japonica cultivars were added for a comparison. In the six cultivars and 16 strains of wild rice, three to 15 alleles were detected per locus with an average of 7.9. The wild rice revealed a large number of unique alleles throughout their chromosomes with much wider ranges of variation than those detected in the six cultivars of O. sativa L.. The alleles found in the wild rice were classified into those specific to wild rice, common to wild rice and cultivars, and those similar to indica or japonica cultivars. According to the classification, the genotype of each of the 16 strains of wild rice was schematically depicted. The genetic variation among individual strains within a collection site was larger than the variation among the collection sites.     

Advantages of Wild Diploid Solanum Species Over Cultivated Diploid Relatives in Potato Breeding Programs

For breeding programs of the tetraploid potato (Solanum tuberosum), both wild and cultivated diploid relatives are valuable sources of genetic diversity. While both types of germplasm are used in breeding programs, there are several advantages to using wild relatives. Diploid relatives are typically crossed with haploids (2n = 2x = 24) from tetraploid S. tuberosum to improve daylength adaptation. Most haploids are male sterile, so they are typically used as female parents. Cultivated diploids, such as members of the Phureja Group, produce male sterile hybrids when crossed as females to haploids; wild relatives, such as S. tarijense, often produce male fertile hybrids. Tuber yield following crosses of haploids to cultivated or wild relatives is often high. However, cultivated relatives generally produce hybrids with a high set of small tubers; hybrids from wild relatives are variable, but many are similar to cultivars in tuber size and set. While tubers of hybrids from cultivated relatives are typically rough, with deep eyes and raised internodes, those from wild relatives are often smooth. Tuber dormancy in hybrids with cultivated relatives is generally short, while that in hybrids with wild species is longer, allowing for storage over winter. Finally, resistance to several major diseases and stresses has been found in wild species and their hybrids with S. tuberosum haploids. The desirable traits in hybrids are transmitted to tetraploids via unilateral sexual polyploidization (4x × 2x or 2x × 4x crosses in which the diploid parent produces 2n gametes). Wild Solanum species are recommended for use in potato breeding programs as sources of genetic diversity that can be adapted easily following hybridization with S. tuberosum haploids.     

New Wild Lactuca Genetic Resources with Resistance Against Bremia lactucae

A total of 1027 genotypes of wild Lactuca spp. (L. serriola, L. saligna, and L. aculeata), originating from Israel, Jordan, East Turkey, Armenia, Kazakhstan, China, and various other countries in Europe were screened for resistance to the lettuce downy mildew (Bremia lactucae Regel). The genotypes of L. serriola (N = 962); L. saligna (N = 43); and L. aculeata (N = 22) were tested at the seedling stage with two isolates of B. lactucae (race Bl-21 and Isr-74) isolated from cultivated lettuce in Italy and Israel, respectively. Altogether, the isolates possess virulence against 17 out of 20 Dm genes/R-factors composing the established differential set of lettuce lines/varieties. They could therefore be used for preliminary detection of the presence of new resistance factors. A total of 83 and three genotypes of L. serriola and L. saligna, respectively, were resistant to infection by each of the two isolates alone as well as to the infection by a mix of the two isolates. These genotypes probably carry previously unknown resistance, and therefore could be suitable for exploitation by breeders and further detailed research. The wild progenitor of lettuce, L. serriola, and related species harbor significant untapped genetic resources for lettuce improvement.     

Sources of winter hardiness in wild lentil

Summary In high altitude areas (> c. 850 m elevation) in west Asia and north Africa, lentil (Lens culinaris) is grown as a spring crop to avoid severe winter cold. But late fall-sown lentil with winter hardiness has higher yield potential in these areas. In this study a total of 245 accessions of wild lentil, 10 of cultivated lentil and three accessions of Vicia montbretii (syn. L. montbretii) were evaluated for winter hardiness in Syria and Turkey during the 1991/92 season. The absolute minimum temperatures were-16°C in Syria and-18.9°C in Turkey and the susceptible indicators were killed at both locations showing that the cold was sufficient for screening. Although winter hardiness was assessed as percentage of survived plants in Syria and as a visual damage rating on a 1–9 scale in Turkey, there was agreement between the winter hardiness ratings with a correlation of r=–0.56, P<0.001. Accessions of L. culinaris ssp. orientalis exhibited the highest level of winter hardiness, on average; whereas accessions of L. nigricans ssp. ervoides were the most susceptible. Correlations revealed that winter hardiness was concentrated among accessions originating from high elevation areas.     

<Emphasis Type="Italic">Persea</Emphasis> (avocados) Phylogenetic Analysis Based on Morphological Characters: Hypothesis of Species Relationships

The genus Persea consists of two subgenera, Persea (known as avocados) and Eriodaphne (known as aguacatillos, avocado-like species). The present study aimed to determine whether the genus Persea is a monophyletic group and whether the division into two subgenera is an artificial one. In conjunction with these goals, a hypothesis of the phylogenetic relationships among Persea species is proposed. Our results suggest that Persea is not a monophyletic group. Two clades of Persea can be recognized. The results suggest that Eriodaphne and Persea should be considered to be independent genera. Various leaf and floral characters contributed for separation into groups. The definition of Eriodaphne is based on fruit color, sessile glands at the base of the stamens, vein prominence and leaf shape. Persea is more closely related to genera Nectandra and Ocotea than Eriodaphne. The 11 species included in Persea are recognized as species. The group is defined by fruit flavor, mature leaf color, number of tertiary divergent veins, and pubescent bracts in the inflorescence. Within this group, a clade of six species in which P. guatemalensis is included is recovered by seed shape, venation pattern relief, and number of fruits per cluster. Moreover, the seed shape supports the separation of P. floccosa and P. zentmyerii. A molecular character analysis is necessary to support the Persea clades proposed herein. Nevertheless the phylogenetic relationships revealed by this study provide new bases for the selection and conservation of the species Persea.     

Sources of Resistance to Stem Rust (<Emphasis Type="Italic">Puccinia graminis</Emphasis> f. sp. <Emphasis Type="Italic">tritici</Emphasis>) in Ethiopian Tetraploid Wheat Accessions

Seedlings of 41 emmer (Triticum dicoccon Schrank) and 56 durum (T. durum Desf.) wheat accessions were evaluated for their response to stem rust (Puccinia graminis f. sp. tritici) infection under greenhouse condition at Kulumsa Agricultural Research Center, Ethiopia. The objectives were to identify tetraploid wheat accessions that could serve as sources of resistance to stem rust, and postulate the stem rust (Sr) resistance genes through multipatotype testing. The test included screening of accessions for stem rust resistance and multipatotype testing. To ensure vigorous screening, a mixture of six isolates (Si-1a, Am-2, Ku-3, Dz-4a, Ro-4 and Na-22) that were collected from severely infected emmer, durum, and bread wheat (Triticum aestivum L.) varieties of major wheat growing areas of Ethiopia was used as inocula. Out of the tested accessions, 18 emmer and 6 durum accessions exhibited low infection types (0–2) response and hence selected as a source of resistance to stem rust infection. Multipatotype testing was done to postulate Sr genes in the selected accessions. In the test, 10 different stem rust races (A2, A9, A11, A14, A16, A17, B3, B7, B15, and B21), 33 stem rust differential lines, and a universal susceptible check variety, Morocco were used, The high (3–4) and low infection type reaction patterns of the tested accessions and differential lines were used to postulate the genes that exhibit gene-for-gene relationship. The presence of Sr 7b, 8b, 9a, 9b, 10, 14, 24, 27, 28, 29, 30, 31, 32 and Tt-3+10 genes were postulated in 16 selected emmer and 5 durum wheat accessions. Efforts to transfer these valuable Sr genes from cultivated tetraploid wheats could be rewarding to get stem rust resistant varieties and boost wheat production.     

Endogenous Hormone Variations in Annual Wild Cicer Species

All processes that regulate of growth, differentiation and development and also stomatal movement are influenced by endogenous hormones in plants. Research related with endogenous hormones is known for cultivated chickpea (Cicer arietinum L.), while in wild chickpeas no data existed. In this study, C. bijugum K.H. Rech.; C. chorassanicum (Bge) M. Pop.; C. cuneatum Hochst. ex Rich.; C. echinospermum P.H. Davis; C. judaicum Boiss.; C. pinnatifidum Jaub. et Sp.; C. reticulatum Ladiz.; and C. yamashitae Kitamura were evaluated for variations in endogenous plant hormone concentrations; indole-3-acetic acid, zeatin, gibberellic acid, and abscisic acid in both leaf and pod. It was concluded that there was a great variation on endogenous plant hormones among the annual wild Cicer species. The data may support selection for various attributes.     

Powdery Mildew Resistance in a Collection of Chinese Barley Varieties

One hundred and forty-seven Chinese barley varieties maintained at the Gene Bank of the National Barley Improvement Centre, Zhejiang, and 84 progenies from these varieties were tested at the seedling stage for their reaction to 32 selected pathotypes of Blumeria graminis f. sp. hordei. Eighteen resistance spectra were identified comprising single or combined resistances from eight known (Ml(Bw), Ml(Ch), Mla7, Mla8, Mla9, Mla13, MlaRu4 and Mlg) and six unknown resistance genes. The most frequent gene was Ml(Bw), which was found in 69 varieties and previously detected in only a few European winter barley varieties. The genes Mla8 and Ml(Ch) were also often present, but other resistance genes were rare. After inoculation, considerably fewer pathogen colonies were observed in ‘Aiganqi’ and one line of ‘Tong5’. Twenty varieties were composed of lines with different resistance genes. China is likely to be a region of origin of the genes Ml(Bw), Mla7, as well as three unknown genes found in original landraces and perhaps another three unknown genes detected in cultivars bred in China. The resistances of varieties from the Zhejiang province and those originating from 11 other Chinese provinces were quite different. Unfortunately, none of the varieties are promising sources of resistance to powdery mildew and China does not seem to be a region suitable for identifying such sources.     

A Preliminary Comparative Evaluation of Genetic Diversity between Chinese and Japanese Wild Soybean (<Emphasis Type="Italic">Glycine soja</Emphasis>) Germplasm Pools using SSR markers

The wild soybean, an annual self-pollinating plant, is the progenitor of soybeans and is extensively distributed in the Far East of Russia, the Korea peninsula, China and Japan. Geographically, Japan is surrounded by sea and insulated from China. We preliminarily evaluate whether the Japanese and Chinese wild soybean germplasm pools are genetically differentiated from each other using SSR markers. The results showed that the two pools have great genetic differentiation. Some loci presented obvious differences in mean genetic divergence (G_ST) value between the two pools. The G_ST among the geographic regions in China was higher than that in Japan. The average within-geographic region gene diversity values (H_S) in the two pools were completely identical and thus the genetic difference between the two pools was mostly attributed to the relatively high level of between-geographic region gene diversity (D_ST) in China. We suggest that Japanese and Chinese wild soybeans should be comparatively independently evolving in phylogeny.     

Genetic Diversity in Accessions of Wild Rice Oryza granulata from South and Southeast Asia

Oryza granulata, an upland wild rice species, represents an unique germplasm for possessing abilities of tolerance to shade and drought, immune to bacterial blight and resistance to brown planthopper. Although low degree of genetic variability has been revealed within its populations, little genetic information at the species level is available in determining rational conservation strategies. Here we used dominant DNA marker random amplified polymorphism DNA (RAPD) to assess the genetic variability among 23 accessions of O. granulata that collected from main distribution areas worldwide. Twenty decamer primers generated a total of 243 bands, with 83.5% of them (203 bands) being polymorphic. Calculation of Shannon index of diversity revealed an average value of 0.42 ± 0.25, indicating that O. granulata maintains a relatively high degree of genetic diversity on the species level. Analysis of genetic dissimilarity (GD) showed that genetic differentiation occurred among studied accessions, which supports the feasibility of current ex situ conservation strategies. We also suggested that information based on population studies, which could be achieved by international co-operation, is needed to conserve this widespread germplasm more effectively.