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.     

Characterization of intergeneric hybrids of <Emphasis Type="Italic">Erianthus rockii</Emphasis> and <Emphasis Type="Italic">Saccharum</Emphasis> using molecular markers

Erianthus rockii, a wild relative of sugarcane, is drought and cold tolerant, and both are potentially important agronomic traits to the sugarcane industry worldwide. As such it is of interest as a source of parental germplasm to sugarcane breeders and is currently being used in sugarcane introgression programs in both China and Australia. To date morphological characters have been used to verify the putative hybrids produced. Two crosses were generated between two different Saccharum species and two E. rockii accessions. Over 400 AFLP markers were used to identify the intergeneric hybrid progeny as well as determine hybrid diversity. Both crosses generated hybrids but efficiency levels were very different and are probably related to the different Saccharum parent used in each cross. Cross 1 was between a Saccharum officinarum and E. rockii and generated 100% hybrid progeny. Cross 2, however, was between a sugarcane hybrid (S. officinarum × Saccharum spontaneum) and E. rockii and only 10% of the progeny were intergeneric hybrids. Inheritance of markers in the progeny was analysed and for both crosses there were equal numbers of markers from both parents indicating n + n transmission of chromosomes. This is the first verification of E. rockii hybrids with molecular markers. It may now be possible to exploit genes of value from E. rockii in sugarcane breeding programs.     

Analysis of Genetic Variation Among Accessions of <Emphasis Type="Italic">Pueraria montana</Emphasis> (Lour.) Merr. var. <Emphasis Type="Italic">lobata</Emphasis> and <Emphasis Type="Italic">Pueraria phaseoloides</Emphasis> (Roxb.) Benth. based on RAPD Markers

Pueraria montana var. lobata and P. phaseoloides originating from tropical Asia and parts of Oceania are ecologically and economically important legumes that are used as green manure, cover crop or forage plants. Conservation and use of plant genetic resources require an understanding of the extent and distribution of genetic diversity in any given region. In this study, genetic variation of five P. montana var. lobata and 16 P. phaseoloides accessions was analysed developing a random amplified polymorphic DNA (RAPD) marker methodology for Pueraria species and thereby creating basic data for follow-up research and the development of conservation strategies. Seeds were collected from native populations in Bac Kan Province, a mountainous region in Northeast Vietnam. P. montana var. lobata presented a high level of variation with 54.3% of the detected markers being polymorphic, whereas P. phaseoloides exhibited an intermediate to high level of variation (45.5%). The P. montana var. lobata accessions clustered in congruence with their eco-geographical origin. For P. phaseoloides no correspondence between sampling sites and genetic differentiation was found. Inter-population differentiation was measured as Jaccard's similarity coefficient (JSC). Mean JSC amounted to 0.35 in P. montana var. lobata and 0.52 in P. phaseoloides. Results are compared to other genetic studies of herbaceous legumes and conservation strategies are suggested.     

Production of Intergeneric Hybrids Between <Emphasis Type="Italic">Sinapis alba</Emphasis> and <Emphasis Type="Italic">Brassica carinata</Emphasis>

Reciprocal crosses were made between Brassica carinata and its related species Sinapis alba. Pollen germination studies indicated the presence post-fertilization barriers in both ways. Sequential ovary–ovule culture helped to realize the intergeneric hybrids from the cross S. alba × B. carinata. The F₁ obtained was confirmed as a hybrid based on morphology, cytology and isozyme studies. The hybrid was backcrossed to its male parent and obtained BC₁ seeds, which were used to raise BC₁ generation. The BC₁ generation plants were further backcrossed to B. carinata in order to develop alloplasmic lines.     

Characterization of Portuguese populations of <Emphasis Type="Italic">Vitis vinifera</Emphasis> L. ssp. <Emphasis Type="Italic">sylvestris</Emphasis> (Gmelin) Hegi

Wild populations of Vitis vinifera L.␣have been located in Portugal. Morphological characterization was carried out in three populations located in Alcácer do Sal, Castelo Branco, and Montemor-o-Novo, and then compared using multivariate discriminant analysis. These populations were from three different hydrological basins, therefore cross-pollination was not possible. It was verified that in each population all plants were different. The data suggest that the frequency of female and male plants is rather variable in wild populations. The morphology of the adult leaf, from the Alcácer do Sal population, had particular features when compared with Castelo Branco and Montemor-o-Novo populations, which were more homogeneous. The length of teeth compared with width at the end of the base, and the density of prostrate hairs between and on main veins (lower side) were the variables which allowed the best discrimination among populations.     

Diversity among landraces of Indian snapmelon (<Emphasis Type="Italic">Cucumis melo</Emphasis> var. <Emphasis Type="Italic">momordica</Emphasis>)

Diversity among 36 snapmelon landraces, collected from 2 agro-ecological regions of India (9 agro-climatic sub-regions), was assayed using RAPD primers, morphological traits of plant habit and fruit, 2 yield-associated traits, pest and disease resistance and biochemical composition (TSS, ascorbic acid, titrable acidity). Typical differences among accessions were observed in plant and fruit characteristics and snapmelon germplasm with high titrable acidity and possessing resistance to downy mildew, Cucumber mosaic virus, Zucchini yellow mosaic virus, Papaya ringspot virus, Aphis gossypii and Meloidogyne incognita was noticed in the collection. RAPD based grouping analysis revealed that Indian snapmelon was rich in genetic variation and region and sub-region approach should be followed across India for acquisition of additional melon landraces. Accessions of var. agrestis and var. momordica clustered together and there was a separate cluster of the accessions of var. reticulatus. Comparative analysis of the genetic variability among Indian snapmelons and an array of previously characterized reference accessions of melon from Spain, Israel, Korea, Japan, Maldives, Iraq, Pakistan and India using SSRs showed that Indian snapmelon germplasm contained a high degree of unique genetic variability which was needed to be preserved to broaden the genetic base of melon germplasm available with the scientific community. N. P. S. Dhillon and Ranjana contributed equally to this work and are considered the first authors.     

Isozyme Variation in <Emphasis Type="Italic">Passiflora</Emphasis> Subgenus <Emphasis Type="Italic">Tacsonia</Emphasis>: Geographic and Interspecific Differentiation Among the Three Most Common Species

In a general study of banana passion fruit genetic resources, diversity was analyzed in the two main cultigens, P. tripartita var. mollissima and P. tarminiana, and their closest wild relative, P. mixta, scoring isozyme bands (IDH,PGM,ACP,PGD,DIA,andPRX) on288 plants from 31 accessions. Polymorphismandallelic richness, Nei diversity indices, and neighbor joining clustering showed that variation was poor in the cultigens in northern and central Colombia, while P. mixta appeared much more polymorphic. The populations of P. tripartita var. mollissima and P. mixta from southern Colombia and Ecuador show higher diversity values and are clearly differentiated from those of central and northern Colombia. This geographic component of variation is even stronger than the interspecific one, which suggests a close relation and a regular gene flow between these two species. In contrast, all the accessions of P. tarminiana constitute a clearly differentiated group, even if some introgression with P. tripartita var. mollissima is also suspected. The high variation observed in the southern region indicates the proximity of a center of diversity for banana passion fruit and collecting in Ecuador, Peru and Bolivia is recommended. The high diversity of P. mixta and the evidence of gene flow with P. tripartita var. mollissima constitute a favorable context for the implementation of in situ conservation strategies.     

Diversity in White Lupin (<Emphasis Type="Italic">Lupinus albus</Emphasis> L.) Landraces from Northwest Iberianplateau

All the accessions (35) of white lupin (Lupinus albus L.) landraces collected from northwest Iberian plateau and maintained at the Spanish germplasm collection (CRF of INIA), were studied with the general objective of assessing the biodiversity of these landraces and to ascertain their value as genetic resources for the development of germplasm adapted to the areas where they were collected with long and chilly winters. The characterization study comprised 51 qualitative and 50 quantitative characters. Quantitative parameters were analyzed by Principal Components Analysis (PCA). The 2-dimensional plot (49.3% of cumulative variability) formed a main group of accessions and 4 outliers (#1, #9, #27 and #28) separated in the first PC. The characters with a higher contribution to the first PC were inflorescence length, leaf petiole length and leaf central foliole area. The presence of alkaloids, the percentage of plants killed by soil borne fungal diseases, the phenology, the yield per plant and yield components were also assessed. Twenty six accessions (the main group in the PCA plot) showed high homogeneity, with the following highlights: bitterness, indeterminate growth habit, early ripeness and spring sowing with the exception of #18, in which seeding date is unknown and it had a later phenology. By contrast accessions #9 and #27 were bitter of autumn sowing with determinate growing habit and they had the longest values of primary inflorescence length and a later phenology when they were sown in spring. Average values for yield and yield components showed a broad range of variation between accessions. The main yield component was the number of pods per plant. Accession #22 had the highest mean seed mass, although this had not significant influence in yield. Accession #17 showed the highest yield and #1 the lowest. This last also had the lowest values of inflorescence length, leaf petiole length and leaf central foliole area. No significant differences of resistance to soil-borne fungi were found between accessions. The year had a significant effect in the phenology, yield and yield components except for number of seeds per pod. The studied material might be of interest for the development of spring sowing germplasm adapted to north Iberian peninsula.     

Seed inoculation with <Emphasis Type="Italic">Bacillus</Emphasis> spp. improves seedling vigour in oil-seed plant <Emphasis Type="Italic">Jatropha curcas</Emphasis> L.

Jatropha (Jatropha curcas L.) is a non-edible oil-seed plant with adaptability to marginal semi-arid lands and wastelands. The Indian Government is promoting jatropha to reduce dependence on the crude oil and to achieve energy independence by the year 2012, under the National Biodiesel Mission. Selected strains of Bacillus spp., either supplemented with or without chitin, were tested for their ability to promote growth of jatropha seedlings in pot culture studies. The strains supported growth of jatropha seedlings up to 42 days after sowing. Among all strains, Bacillus pumilus (IM-3) supplemented with chitin showed over all plant growth promotion effect resulting in enhanced shoot length (113%), dry shoot mass (360%), dry root mass (467%), dry total plant mass (346%), leaf area (256%), and chlorophyll content (74%) over control. Treating seeds with strain IM-3 without chitin resulted in enhanced dry shoot mass (473%), dry total plant mass (407%), and chlorophyll content (82%). However, Bacillus polymyxa (KRU-22) with chitin supported maximum root length (143%). Either strain IM-3 alone or in combination with other promising strains could be promoted further for enhanced initial seedling growth of jatropha.     

The Inheritance of Morphological and Biochemical Traits Introgressed into Common Wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) from <Emphasis Type="Italic">Aegilops speltoides</Emphasis> Tausch

The genetic control of morphological characters and gliadin composition was studied in two bread wheat lines with introgressed segments from Aegilops speltoides Tausch. It was found that the transferred trait of leaf hairiness is controlled by one dominant gene, non-allelic to the known gene, Hl1. It was localized in 7B chromosome. Whole plant non-glaucousness is under the control of an inhibitor gene, allelic to the gene W1^I of wheat located on chromosome 2B. This gene was found to be epistatic to the gene controlling spike waxlessness. The introgressed gene for spike glume color was found to be allelic to the Rg1 gene located on 1BS of common wheat, but it was linked with another allele of the gliadin locus Gli-B1.     

Dispersal of durum wheat [<Emphasis Type="Italic">Triticum turgidum</Emphasis> L. ssp. <Emphasis Type="Italic">turgidum</Emphasis> convar. <Emphasis Type="Italic">durum</Emphasis> (Desf.) MacKey] landraces across the Mediterranean basin assessed by AFLPs and microsatellites

A comprehensive characterization of crop germplasm is critical to the optimal improvement of the quality and productivity of crops. Genetic relationships and variability were evaluated among 63 durum wheat landraces from the Mediterranean basin using amplified fragment length polymorphisms (AFLPs) and microsatellites markers. The genetic diversity indices found were comparable to those of other crop species, with average polymorphism information content (PIC) values of 0.24 and 0.70 for AFLP and microsatellites, respectively. The mean number of alleles observed for the microsatellites loci was 9.15. Non-metric multi-dimensional scaling clustered the accessions according to their geographical origin with the landraces from the South shore of the Mediterranean Sea closely related. The results support two dispersal patterns of durum wheat in the Mediterranean basin, one through its north side and a second one through its south side.     

A preliminary study of the genetic diversity of Bolivian oca (<Emphasis Type="Italic">Oxalis tuberosa</Emphasis> Mol.) varieties maintained<Emphasis Type="Italic"> in situ</Emphasis> and<Emphasis Type="Italic"> ex situ</Emphasis> through the utilization of ISSR molecular markers

ISSR molecular markers have been used to investigate genetic diversity of oca (Oxalis tuberosa Mol.), an Andean neglected tuber crop species. Sampling procedure allowed a preliminary study of the genetic diversity at the intra- and intervarietal levels. Twenty tuber lots conserved in situ in the microcentre of Candelaria and ex situ in the Toralapa Centre (Bolivia) were identified. Four ISSR primers amplified a total of 25 fragments of which 17 (68%) were polymorphic. These experiments show that the structure of oca varieties is mainly based upon vernacular names with a greater differentiation among tuber lots than within them, supporting agromorphological data. ISSR technique enlightened the existence of heterogeneous varieties in oca and divergence between in situ and ex situ conservation strategies. These observations are potentially linked to the different ways of management of tubers in these two conservation systems.     

Genetic diversity of <Emphasis Type="Italic">rbc</Emphasis>L gene in <Emphasis Type="Italic">Elymus trachycaulus</Emphasis> complex and their phylogenetic relationships to several Triticeae species

Elymus trachycaulus complex species are known for their morphological variability, but little is known about their genetic basis. The phylogenetic relationships among the E. trachycaulus complex, and their systematic relation to other species in Triticeae remain unknown. Nucleotide diversity of ribulose-1,5 bisphosphate-carboxylase (rbcL) gene in E. trachycaulus complex species and several other Triticeae was first characterized and compared. A primary conclusion of the present study is that nucleotide diversity for rbcL gene in E. trachycaulus species was detected with the estimates of nucleotide diversity θ = 0.00039 and π = 0.00043. The estimate of nucleotide diversity in rbcL gene for species with different genome constitution here ranged from 0.00099 (π) and 0.00099 (θ) for the species with Ns genome to 0.00226 (π) and 0.00291 (θ) for the species with St genome. The phylogenetic relationships of these species were assessed using these rbcL sequences. A total of 47 variable positions including 19 parsimony-informative sites were detected among 24 accessions of 18 species/subspecies. The species with St, H/I and Ns genomes well separated from each other, and formed a three distinct clades with higher bootstrap values support for both Parsimony and NJ analyses. The St genome containing species is sister group of H/I genome containing species. Our result confirms that Pseudoroegneria is the maternal genome donor to these Elymus species studied here, regardless of their distribution. Elymus trachycaulus complex are more related to each other than to E. glaucescens, E. patagonicus, and E. solandri. This study suggested that Elymus species with StH genomes may form from multiple closely related sets of donors.     

Diversity and origin of cultivated and citron type watermelon (<Emphasis Type="Italic">Citrullus lanatus)</Emphasis>

Cultivated (Citrullus lanatus var. lanatus) and citron type (var. citroides) watermelon collected from different areas on the African continent are remarkably diverse in fruit and seed morphology. Chloroplast DNA investigations using PCR-RFLP and sequencing analysis of several non-coding regions were conducted to infer their biogeographic and evolutionary relationships, origin and domestication history. Variability within C. lanatus was observed at regions of high A + T content, resulting in indels and transversions mainly. Distinct chlorotype lineages were identified separating the cultivated and egusi-type watermelon from var. citroides accessions. This suggests an ancient split from a common ancestor and haplotype fixation. Three haplotypes as a result of relatively recent indel events were detected within var. citroides. The geographical range of two of the main citroides haplotypes is relatively similar across southern Africa. Accessions with the most ancient citroides haplotype originated in Swaziland and South Africa resulting in colonization routes from this area all over the world. Chloroplast divergence is not associated with morphological divergence. The cultivated and wild watermelon appear to have diverged independently from a common ancestor, possibly C. ecirrhosus from Namibia.     

Production and analysis of reciprocal hybrids between <Emphasis Type="Italic">Asparagus officinalis</Emphasis> L. and <Emphasis Type="Italic">A. schoberioides</Emphasis> Kunth

The genus Asparagus (Asparagaceae) encompasses 100–300 species, including the important vegetable crop, A. officinalis (garden asparagus). Previous attempts to hybridize garden asparagus with A. densiflorus (Kunth) Jessop, with the aim of introducing disease resistance, were unsuccessful because of the failure of endosperm development. In the present study, reciprocal interspecific hybrids between garden asparagus and A. schoberioides Kunth were generated by hand pollination. The F1 hybrids were analyzed by using both morphological and molecular techniques. This is the first report describing the production of an interspecific hybrid between garden asparagus at the diploid level (2n = 2x = 20) and its diploid (2n = 2x = 20) wild relative, A. schoberioides. Morphological characteristics of candidate hybrids were a mixture of those found in the parents, and cytological and RFLP analyses confirmed that morphologically intermediate plants were indeed diploid hybrids of those two species. In other words, post-zygotic isolation is not complete between phylogenetically distinct these two species. Our results suggest that other Asparagus species may be capable of hybridizing with A. officinalis and that introducing wild characters through interspecific hybridization may offer advantages for breeding for novel traits. Takuro Ito and Toshinori Ochiai authors are contributed equally to this work     

Genetic diversity and conservation of two endangered eggplant relatives (<Emphasis Type="Italic">Solanum vespertilio</Emphasis> Aiton and <Emphasis Type="Italic">Solanum lidii</Emphasis> Sunding) endemic to the Canary Islands

Solanum vespertilio Aiton and Solanum lidii Sunding are endemic, endangered wild species from the Canary Islands. These species are of potential value for eggplant (S. melongena) breeding, given that they are part of the secondary genepool of this crop. We study genetic diversity with amplified fragment length polymorphisms (AFLPs) markers from 5 populations of S. vespertilio (47 samples) and 3 of S. lidii (26 samples). Five related African species (S. dasyphyllum Schumach. et Thonn., S. delagoense Dunal, S. campylacanthum Hochst., S. panduriforme E. Mey, S. aff. violaceum Ortega) were also included in the analysis. A total of 235 AFLP markers included 178 and 156 that were polymorphic in S. vespertilio and S. lidii, respectively. Analysis of genetic distance, phenograms, and principal component plots showed that these rare Canarian species are differentiated (G _ST = 0.412) from the continental materials and that Solanum vespertilio is more distinct to its African congeners than is S. lidii. There is a relatively high level of differentiation between the two species (G _ST = 0.373), that presumably reflects geographic restrictions (S. lidii to Gran Canaria; S. vespertilio essentially to Tenerife). However, both species have similar levels of total diversity. We speculate that the combination of the many unusual reproductive features (andromonoecy, zygomorphy, heteranthery and weak enantiostyly in S. vespertilio) help explain genetic diversity that is high for self compatible species. The high genetic diversity may also indicate populations were larger in the past. A decrease in population size could contribute to the relatively low genetic differentiation among the populations. The data presented herein provide the foundation for initiation of ex situ and in situ conservation programs for these wild relatives of eggplant. This paper is dedicated to the memory of Dr. Richard N. Lester, who made significant contributions to the taxonomy, biosystematics and conservation of genetic resources of African species of Solanum.     

Phenotypic diversity in the pigeonpea (<Emphasis Type="Italic">Cajanus cajan</Emphasis>) core collection

The pigeonpea core collection developed at ICRISAT genebank consists of 1,290 accessions from 53 countries. The core collection, which includes selected lines in extra early, early, medium and late maturity groups was evaluated for 18 qualitative and 16 quantitative characters during the 2004 rainy season, to assess the phenotypic diversity and determine the relative importance of different characters in evaluating pigeonpea germplasm accessions. The four maturity groups differed significantly for all characters under study. The medium maturity group showed significantly higher mean number of primary, secondary and tertiary branches, number of racemes, pod bearing length, pods per plant, shelling percent and plot seed yield. Late maturity group showed significantly higher mean for leaf size, plant height, pod length, seeds per pod and 100-seed weight, indicating this group as a good source of vegetable pigeonpea. Significant positive correlations were found between number of secondary branches and pods per plant in extra early group (r = 0.756), late maturity group (r = 0.776) and entire core (r = 0.728) and between number of racemes and pods per plant in all maturity groups and entire core. Principal coordinate and principal component analysis showed that seven qualitative and nine quantitative traits were important in explaining multivariate polymorphism. The Shannon–Weaver diversity index (H′) varied for different maturity groups and traits. Phenotypic diversity, averaged over all the 16 characters, increases from extra early group (0.36 ± 0.04) to late maturity group (0.42 ± 0.04) suggesting that medium and late maturity groups have greater diversity compared to extra early and early maturity groups.