Domestication ofEleusine coracana

Eleusine coracana (L.) Gaertn. subsp.coracana (Finger millet or eleusine) is a cereal that is widely cultivated in Africa and India. Archaeological records of finger millet are few and unsatisfactory. But, distribution, linguistic and historical evidence seem to suggest an African rather than Indian origin of the crop. Data from morphology, supplemented with cytogenetical observations and distribution revealed thatE. coracana subsp.africana is wild finger millet. This subspecies is widely distributed along the highlands of East Africa. Consequently, it is concluded that finger millet originated in the East African Highlands and was subsequently introduced into India.     

SYSTEMATICS AND EVOLUTION OF ELEUSINE CORACANA (GRAMINEAE)

Finger millet (Eleusine coracana (L.) Gaertn. subsp. coracana) is cultivated in eastern and southern Africa and in southern Asia. The closest wild relative of finger millet is E. coracana subsp. africana (Kennedy-O'Byrne) Hilu & de Wet. Wild finger millet (subsp. africana) is native to Africa but was introduced as a weed to the warmer parts of Asia and America. Derivatives of hybrids between subsp. coracana and subsp. africana are companion weeds of the crop in Africa. Cultivated finger millets are divided into five races on the basis of inflorescence morphology. Race coracana is widely distributed across the range of finger millet cultivation. It is present in the archaeological record of early African agriculture that may date back 5,000 years. Racial evolution took place in Africa. Races vulgaris, elongata, plana, and compacta evolved from race coracana, and were introduced into India some 3,000 years ago. Little independent racial evolution took place in India.     

Isozymes of Eleusine (Gramineae) and the origin of finger millet

The predominantly African grass genus Eleusine comprises nine species, including diploids and tetraploids based on n = 8, 9, and 10. Among the polyploids are the important crop finger millet, Eleusine coracana subsp. coracana, and its putative wild ancestor, E. coracana subsp. africana. Eleusine coracana is believed to be an allotetraploid derived by hybridization between E. indica and an unknown diploid. To evaluate this hypothesis, 16 isozyme loci coding nine enzymes were compared among seven of the nine Eleusine species (E. intermedia and E. semisterilis were unavailable). Genetic variability differed substantially among diploid species, ranging from P = 0.563, A = 1.6, H = 0.208 in E. indica to P = 0.188, A = 1.2, H = 0.042 in E. jaegeri. The diploids tended to be genetically distinct, with values of Rogers' Similarity ranging from S = 0.294 (E. jaegeri/floccifolia) to S = 0.794 (E. indica/tristachya). Both subspecies of the tetraploid E. coracana exhibited fixed heterozygosity at several loci, verifying their hypothesized allotetraploid status. Both tetraploids also possessed E. indica marker alleles at all loci, corroborating ancestry by this taxon. Genotypes of the non-indica ancestor, inferred separately for each tetraploid, differed substantially from all candidate diploids and also from each other. These data indicate that 1) none of the candidate diploids investigated is likely to have been the non-indica ancestor of E. coracana, and 2) the non-indica ancestor of the wild tetraploid may differ from that of the crop. The latter conclusion is inconsistent with the complete chromosomal homology exhibited between the two tetraploid subspecies, indicating the need for additional evidence bearing on their relationships.     

Population Structure and Diversity in Finger Millet (Eleusine coracana) Germplasm

A genotypic analysis of 79 finger millet accessions (E. coracana subsp. coracana) from 11 African and five Asian countries, plus 14 wild E. coracana subsp. africana lines collected in Uganda and Kenya was conducted with 45 SSR markers distributed across the finger millet genome. Phylogenetic and population structure analyses showed that the E. coracana germplasm formed three largely distinct subpopulations, representing subsp. africana, subsp. coracana originating from Africa and subsp. coracana originating from Asia. A few lines showed admixture between the African and Asian cultivated germplasm pools and were the result of either targeted or accidental intercrossing. Evidence of gene flow was also seen between the African wild and cultivated subpopulations, indicating that hybridizations among subspecies occur naturally where both species are sympatric. The genotyping, combined with phylogenetic and population structure analyses proved to be very powerful in predicting the origin of breeding materials. The genotypic study was complemented by a phenotypic evaluation. The wild and cultivated accessions differed by a range of domestication-related characters, such as tiller number, plant height, peduncle length, seed color and grain yield. Significant differences in plant architecture and yield were also identified between the Asian and African subpopulations. The observed population structure within cultivated finger millet is consistent with the theory that, after the introduction of finger millet from Africa into India via the trade routes some 3000 years ago, the two germplasm pools remained largely isolated until recent times. The significantly lower diversity present within the Asian subpopulation also suggests that it arose from a relatively small number of founder plants.     

Comparative evaluation of genetic diversity using RAPD,SSR and cytochrome P450 gene based markers with respect to calcium content in finger millet (<Emphasis Type="Italic">Eleusine coracana</Emphasis> L. Gaertn.)

Genetic relationships among 52 Eleusine coracana (finger millet) genotypes collected from different districts of Uttarakhand were investigated by using randomly amplified polymorphic DNA (RAPD), simple sequence repeat (SSR) and cytochrome P450 gene based markers. A total of 18 RAPD primers, 10 SSR primers, and 10 pairs of cytochrome P450 gene based markers, respectively, revealed 49.4%, 50.2% and 58.7% polymorphism in 52 genotypes of E. coracana. Mean polymorphic information content (PIC) for each of these marker systems (0.351 for RAPD, 0.505 for SSR and 0.406 for cyt P450 gene based markers) suggested that all the marker systems were effective in determining polymorphisms. Pair-wise similarity index values ranged from 0.011 to 0.999 (RAPD), 0.010 to 0.999 (SSR) and 0.001 to 0.998 (cyt P450 gene based markers) and mean similarity index value of 0.505, 0.504 and 0.499, respectively. The dendrogram developed by RAPD, SSR and cytochrome P450 gene based primers analyses revealed that the genotypes are grouped in different clusters according to high calcium (300–450 mg/100 g), medium calcium (200–300 mg/100 g) and low calcium (100–200 mg/100 g). Mantel test employed for detection of goodness of fit established cophenetic correlation values above 0.95 for all the three marker systems. The dendrograms and principal coordinate analysis (PCA) plots derived from the binary data matrices of the three marker systems are highly concordant. High bootstrap values were obtained at major nodes of phenograms through WINBOOT software. Comparison of RAPD, SSR and cytochrome P450 gene based markers, in terms of the quality of data output, indicated that SSRs and cyt P450 gene based markers are particularly promising for the analysis of plant genome diversity. The genotypes of finger millet collected from different districts of Uttarakhand constitute a wide genetic base and clustered according to calcium contents. The identified genotypes could be used in breeding programmes and amajor input into conservation biology of cereal crops.     

Genomic in situ hybridization identifies genome donor of finger millet (Eleusine coracana)

Eleusine coracana, commonly called finger millet, is an important cereal of semi-arid regions, cultivated in parts of Africa and India for its grain. It is reported to be an allotetraploid with a chromosome number 2n = 4x = 36, and diploid species E. indica, with chromosome number 2n = 2x = 18, is considered to be one of its genome donors. In situ hybridization of the E. coracana genome with the genomic DNA of various diploid species of the genus confirmed that E. indica is one of the genome donors to E. coracana and that E. floccifolia is another genome contributor to this allotetraploid species. In situ hybridization also showed a close genomic relationship between 4 diploid species, E. indica, E. floccifolia, E. tristachya and E. intermedia, and also between these and tetraploid species E. coracana. The common genomic in situ hybridization (GISH) signals of the genomic DNA of E. indica and E. tristachya on 15–18 chromosomes of E. coracana clearly indicated that these 2 species have a close genomic similarity. GISH on 25–27 chromosomes of E. coracana withthe genomic DNA of E. intermedia and cross in situ hybridization signals on the chromosomes of E. coracana with genomic DNA of E. intermedia and E. indica or E. intermedia and E. floccifolia has showed that E. intermedia may be an intermediate species of E. indica and E. floccifolia. Received: 15 May 2000 / Accepted: 4 September 2000     

Use of SSR,RAPD markers and protein profiles based analysis to differentiate <Emphasis Type="Italic">Eleusine coracana</Emphasis> genotypes differing in their protein content

Fifty-two genotypes of Eleusine coracana collected from Uttarakhand hills were subjected to simple sequence repeat (SSR), random amplified polymorphic DNA (RAPD)-PCR and protein profiling analysis to investigate the variation in protein content. The main objective of the present study was to detect variability among E. coracana and also assess the discriminating ability of these three molecular methods. A total of 21 RAPD and 24 SSR primers were assayed for their specificity in detecting genetic variability in E. coracana, of which 20 RAPD and 21 SSR primers were highly reproducible and were found suitable for use in PCR analysis. Assessing genetic diversity among E. coracana genotypes by RAPD-PCR using 20 polymorphic primers yielded 56 different RAPD markers which clustered the genotypes into different groups on the basis of protein content. Similarly, SSR-PCR with 21 polymorphic primers clustered the genotypes into different groups. On the other hand, biochemical typing of E. coracana using whole seed proteins generated profiles that showed no major difference indicating the technique to be not useful in typing genotypes of this crop. However, a few of the genotypes showed the presence of a unique band of 32 kDa that needs to be further investigated to understand the role of the protein from nutritional point of view, if any. In the present study, significant negative correlation (r = −0.69*) was found between the protein and calcium content of finger millet genotypes. Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresis based seed storage proteins generated profiles showed no major differences in banding pattern among 52 finger millet genotypes while quantitative estimation of seed storage protein fractions using Lowry method revealed that glutelin was highest followed by prolamin, globulin and albumin.     

Genome organization and polyploid evolution in the genus Eleusine (Poaceae)

 Eleusine (Poaceae) includes six diploid and three polyploid species and has three basic chromosome numbers, x=8, 9 and 10. The species are annual as well as perennial and all are wild except E. coracana, which is cultivated for grain and fodder in Africa and the Indian subcontinent. Eleusine coracana and E. africana have the same genome and chromosome number (2n=36). Eleusine indica and E. floccifolia are identified as two genome donors to these polyploid species. Eleusine kigeziensis is the third polyploid species of the genus with 2n=38. Its genome may have come from E. jaegeri and from one of the species with x=9, most probably from E. indica. Eleusine indica, E. tristachya, E. floccifolia and E. intermedia with x=9 and two polyploid species, E. coracana and E. africana, are closely related and there is free genetic flow between them. Eleusine multiflora with x=8 is significantly different in morphology and at genomic level from other species. Eleusine jaegeri with x=10 is morphologically similar to E. indica, however, more information is needed to ascertain its position in the genus. Eleusine coracana, which is commonly called finger millet, is a potential and nutritious crop for the increasing population of the world, particularly in arid and semi-arid regions. It can also serve as a gene pool for various important characters and disease resistant genes. Received February 11, 2002; accepted May 27, 2002 Published online: October 14, 2002 Addresses of the authors: Madho Singh Bisht and Yasuhiko Mukai (e-mail: ymukai@cc.osaka-kyoiku.ac.jp), Laboratory of Plant Molecular Genetics, Division of Natural Science, Osaka Kyoiku University, 4-698-1 Asahigaoka, Kashiwara, Osaka 582-8582, Japan.     

Flavonoid patterns and systematics in Eleusine

A survey of leaf flavonoids was conducted on Eleusine coracana ssp. coracana and ssp. africana, E. indica, E. multiflora, E. tristachya, E. floccifolia, and E. compressa. Twenty phenolic compounds were detected. Those identified were: orientin, isoorientin, vitexin, isovitexin, saponarin, violanthin, lucenin-1, and tricin. The study revealed a general generic flavonoid pattern except for E. compressa, which occupies an isolated position in Eleusine. Flavonoids of the perennial E. floccifolia and the annuals E. multiflora and E. tristachya are markedly different from those of cultivated E. coracana, suggesting that these species are only distantly related to the crop. The morphologically well defined E. coracana—africana—indica group also forms a unit in respect of flavonoids. Subspecies africana exhibits a higher flavonoid similarity to ssp. coracana (finger millet) than does E. indica. The weedy race of ssp. africana usually combines flavonoids of both the wild and domesticated subspecies. The flavonoid pattern of the dedza race of ssp.africana is identical to that of finger millet, suggesting either a direct origin of the crop from this race, or extensive introgression from the crop into ssp. africana. A lack of qualitative differences in flavonoids between cultivated races of finger millet is indicative of the genetic stability of these compounds. The flavonoid data confirms the domestication of finger millet from ssp. africana.     

Identification of the ``a' Genome of Finger Millet Using Chloroplast DNA

Finger millet (Eleusine corocana subsp. coracana), an important cereal in East Africa and India, is a tetraploid species with unknown genomic components. A recent cytogenetic study confirmed the direct origin of this millet from the tetraploid E. coracana subsp. africana but questioned Eleusine indica as a genomic donor. Chloroplast (ct) DNA sequence analysis using restriction fragment pattern was used to examine the phylogenetic relationships between E. coracana subsp. coracana (domesticated finger millet), E. coracana subspecies africana (wild finger millet), and E. indica. Eleusine tristachya was included since it is the only other annual diploid species in the genus with a basic chromosome number of x = 9 like finger millet. Eight of the ten restriction endonucleases used had 16 to over 30 restriction sites per genome and were informative. E. coracana subsp. coracana and subsp. africana and E. indica were identical in all the restriction sites surveyed, while the ct genome of E. tristachya differed consistently by at least one mutational event for each restriction enzyme surveyed. This random survey of the ct genomes of these species points out E. indica as one of the genome donors (maternal genome donor) of domesticated finger millet contrary to a previous cytogenetic study. The data also substantiate E. coracana subsp. africana as the progenitor of domesticated finger millet. The disparity between the cytogenetic and the molecular approaches is discussed in light of the problems associated with chromosome pairing and polyploidy.     

An integrated genetic map and a new set of simple sequence repeat markers for pearl millet, <Emphasis Type="Italic">Pennisetum glaucum</Emphasis>

Over the past 10 years, resources have been established for the genetic analysis of pearl millet, Pennisetum glaucum (L.) R. Br., an important staple crop of the semi-arid regions of India and Africa. Among these resources are detailed genetic maps containing both homologous and heterologous restriction fragment length polymorphism (RFLP) markers, and simple sequence repeats (SSRs). Genetic maps produced in four different crosses have been integrated to develop a consensus map of 353 RFLP and 65 SSR markers. Some 85% of the markers are clustered and occupy less than a third of the total map length. This phenomenon is independent of the cross. Our data suggest that extreme localization of recombination toward the chromosome ends, resulting in gaps on the genetic map of 30 cM or more in the distal regions, is typical for pearl millet. The unequal distribution of recombination has consequences for the transfer of genes controlling important agronomic traits from donor to elite pearl millet germplasm. The paper also describes the generation of 44 SSR markers from a (CA)_n-enriched small-insert genomic library. Previously, pearl millet SSRs had been generated from BAC clones, and the relative merits of both methodologies are discussed.     

An integrated DArT-SSR linkage map of durum wheat

Genetic mapping in durum wheat (Triticum durum Desf.) is constrained by its large genome and allopolyploid nature. We developed a Diversity Arrays Technology (DArT) platform for durum wheat to enable efficient and cost-effective mapping and molecular breeding applications. Genomic representations from 56 durum accessions were used to assemble a DArT genotyping microarray. Microsatellite (SSR) and DArT markers were mapped on a durum wheat recombinant inbred population (176 lines). The integrated DArT-SSR map included 554 loci (162 SSRs and 392 DArT markers) and spanned 2022 cM (5 cM/marker on average). The DArT markers from durum wheat were positioned in respect to anchor SSRs and hexaploid wheat DArT markers. DArT markers compared favourably to SSRs to evaluate genetic relationships among the durum panel, with 1315 DArT polymorphisms found across the accessions. Combining DArT and SSR platforms provides an efficient and rapid method of generating linkage maps in durum wheat.     

Efficiency of RAPD, SSR and Cytochrome P450 gene based markers in accessing genetic variability amongst finger millet (Eleusine coracana) accessions

Finger millet (Eleusine coracana L.) is an important crop used for food, forage, and industrial products. Three DNA marker techniques, random amplified polymorphic DNA (RAPD), simple sequence repeat (SSR) and cytochrome P₄₅₀ gene based markers were used for the detection of genetic polymorphism in 83 accessions of finger millet collected from various geographical regions of India and Africa. A total of 18 RAPD, 10 SSR and 10 pairs of cytochrome P₄₅₀ gene based markers were generated 56.17, 70.19 and 54.29% polymorphism, respectively. Mean polymorphism information content (PIC) for each of these marker systems (0.280 for RAPD, 0.89 for SSR and 0.327 for cytochrome P₄₅₀ gene based markers) suggested that SSR marker were highly effective in determining polymorphism. The phenograms based on the three markers data indicate that genotypes from different geographical regions are clearly distinguishable as separate clusters. Mantel test employed for detection of goodness of fit established cophenetic correlation values above 0.90 for all the three marker systems. The dendrograms and PCA plots derived from the binary data matrices of the three marker systems are highly concordant. High bootstrap values were obtained at major nodes of phenograms through WINBOOT software. Based on the results of present study, SSR and cytochrome P₄₅₀ gene based markers appear to be particularly useful for the estimation of genetic diversity. This study reveals the potential of RAPD, SSR and gene based markers for characterizing germplasm of Eleusine coracana and narrow down the vast germplasm into distinct core groups.     

ARCHAEOBOTANICAL STUDIES OF ELEUSINE CORACANA SSP. CORACANA (FINGER MILLET)

Two controversial archaeological specimens of finger millet, Eleusine coracana ssp. coracana (L.) Gaertn., were examined by light and scanning electron microscopy. Identification of the material was based on morphological and anatomical comparison with laboratory carbonized grains of modern Eleusine. Seed morphology of the Indian archaeological collection did not conform with those of domesticated or wild species of Eleusine. The other archaeological collection examined is from Ethiopia. It is estimated to date back to the third millennium B.C. These well preserved inflorescence fragments were positively identified as finger millet. If the suggested date is correct, they represent the oldest archaeological record for the crop, as well as the oldest agricultural record for Africa south of the Sahara. These findings support biosystematic evidence for an East African origin of finger millet which leaves India as a secondary center of diversity.     

The ‘A’ genome donor of Eleusine coracana (L.) Gaertn. (Gramineae)

Summary In an attempt to discover A and B genome donor(s) to finger millet, Eleusine coracana, or its progenitor species, E. africana (both allotetraploid 2n=4x=36), five diploid species, E. Indica, E. Floccifolia, E. multiflora, E. tristachya and E. intermedia, were crossed to finger millet and its progenitor taxon. Crosses were successful only with E. coracana. Three combinations of triploid hybrids E. coracana x E. indica, E. coracana x E. floccifolia, and E. coracana x E. multiflora were obtained and analysed. Meiotic behaviour was perfectly normal in parental species. The regular number of 18 bivalents in E. coracana, 9 bivalents in E. indica, E. intermedia, E. tristachya and E. floccifolia and 8 bivalents in E. multiflora were invariably noticed. In E. coracana x E. indica hybrids a mean chromosome pairing of 8.84_I+8.80_II+0.03_III+0.10_IV per cell was found. About 86.5% of the cells showed the typical 9_I+9_II configuration, suggesting that E. indica (AA) is one of the diploid genome donors to cultivated species E. coracana. A mean chromosome pairing of 11.08_I+7.63_II+0.16_III+0.04_IV per cell was found in E. coracana x E. floccifolia hybrids. Two to ten bivalents and varying numbers of univalents were seen in 55% of the cells. About 45% of the cells showed the 9_I+9_II configuration. Various evidence suggests that perennial E. floccifolia is a primitive member of the A genome group of Eleusine species, and it may not be a genome donor to E. coracana. In E. coracana x E. multiflora hybrids (2n=26) mean chromosome pairing of 21.45_I+1.97_II+0.13_III+0.04_IV per cell was found. About 91% of the cells were observed to have 20–26 univalents. Only a small percentage of the cells contained bivalents or multivalents. This pairing behaviour indicates that E. multiflora lacks genomic homology with the A or B genome of E. coracana. Genomically E. multiflora is a distinct species and a genomic symbol of C is assigned to it. Identification of the B genome donor species to cultivated millet. E. coracana remains elusive.     

Isolation and characterization of a trypsin inhibitor from finger millet

A trypsin inhibitor was isolated from finger millet (Eleusine coracana) by ammonium sulphate fractionation, chromatography on CM-Sephadex and Sepha     

基因组原位杂交鉴定牛筋草AA基因组在穇子染色体上的分布及探针长度优化方法

采用基因组原位杂交(Genomic in situ hybridization,GISH)方法研究了牛筋草(Eleusine indica)AA基因组在穇子(E.coracana)染色体上的分布,并探讨了AA、BB基因组的同源关系。用超声波破碎法进行预剪切,以缺口平移法标记的牛筋草总DNA为探针,BB基因组的E.floccifolia(Forssk.)Spreng.总DNA为封阻,与AABB基因组穇子的中期染色体进行杂交。结果表明,牛筋草AA基因组分布在穇子的18条染色体上。不加封阻或加过量封阻均不能鉴别AA基因组,说明AA和BB基因组间的分化程度不大,双方共享的重复序列较多。牛筋草与E.floccifolia总DNA分别用超声波破碎2 min和3 min后,可得到峰值为300-750 bp的DNA片段,这说明不同物种的超声波破碎时间需要调整,以获得合适长度的探针。     

Variation in response of accessions of minor millets,Pennisetum americanum (L.) Leeke (pearl millet) and Eleusine coracana (L.) Gaertn (finger millet), and Eragrostis tef (Zucc.) Trotter (tef) to salinity in early seedling growth

The response to increasing NaCl concentration of seedlings of 25 accessions of Ethiopian land races of each of Pennisetum americanum (L.) Leeke (pearl millet) and Eleusine coracana (L.) Gaertn (finger millet), and 15 accessions of Eragrostis tef (Zucc.) Trotter (tef), was examined after two week's growth in NaCl solution culture. Although increasing NaCl concentration significantly reduced seedling root lengths, there was considerable variation within, and between accessions within each species.Analysis based upon a non-linear least square inversion method, using root length data, revealed significant differences in accessions of P. americanum and E. tef on the basis of the estimated salinity threshold, C _t , the NaCl concentrations at which root length begins to decrease. C _t did not differ significantly between E. coracana accessions. Estimates of C₅₀ and C₀, mininum concentrations causing a 50% decrease in root length, and zero root growth respectively, revealed differences between and within accessions for all three species. Overall, finger millet was more tolerant than tef, which was more tolerant than pearl millet. There is clear evidence that differences in tolerance are genetically based from broad sense heritability estimates.