Evaluation of amplified fragment length polymorphism markers in tef, Eragrostis tef (Zucc.) Trotter, and related species

Tef is an important cereal crop in Ethiopia. This study was conducted to investigate (1) genetic diversity within and among three Eragrostis species (E. tef, E. pilosa and E. curvula), and (2) the relationship between E. tef, E. pilosa and E. curvula. A total of 529 AFLP markers were obtained, out of which 58% (368) were polymorphic, using 10 primer, combinations. The three species were separated distinctly using amplified fragment length polymorphism (AFLP), However, diversity revealed at the morphological trait level was not commensurate with that observed for AFLP. This was due to the small number of morphological traits available and their interaction with the environment. Within tef, ‘Rubicunda’ and DZ‐01‐1093 were found to be distantly related to the rest of the tef accessions. The diversity within species was such that E. pilosa was the most diverse followed by E. curvula and E. tef. Moreover, E. pilosa was more closely related to E. tef than E. curvula. Therefore, further study is needed of E. pilosa accessions and of ‘Rubicunda’ and DZ‐01‐1093 in a crossing programme to generate a population for selection and/or genetic mapping. A total of 19 cultivars or accessions had one or more unique fragments using one or more AFLP primers, indicating the potential of the technology in fingerprinting tef in a breeding or seed multiplication programme.     

Qualitative trait variation in Tef [Eragrostis tef (Zucc.) Trotter] germplasm from Western and Southern Ethiopia

Three thousand tef [Eragrostis tef (Zucc.) Trotter] single panicle derived lines representing 60 populations from western and southern parts of Ethiopia were characterized for panicle form, pigmentation of lemma and anther, caryopsis color, number of main shoot culm internodes, and counts of florets/spikelet at the basal, middle and apical parts of the panicle at Debre Zeit Agricultural Research Center during the 1999 main season. The objectives were to assess the diversity patterns of the germplasm with respect to regions and altitude zones. Among the eight characters, high Shannon-Weaver diversity indices (H’) were noted for anther color (0.71) and number of apical spikelet florets (0.68), and the lowest occurred for panicle form (0.40). Monomorphism (H’ = 0.00) was observed for panicle form, lemma color and number of middle spikelet florets each in three different populations. The overall diversity index for all populations was 0.53. In the analysis of variance of H’ estimates, substantial (p <0.05) regional differences were obtained for lemma color, number of culm internodes, and counts of middle and basal spikelet florets. Clinal variation was significant for panicle form, lemma and seed color, and for the overall mean of traits. Over all traits, mean H’ values declined from 0.60 to 0.46 with an increase in the altitude zone of origin from below 1800 to over 2400 meters above sea level. Overall, the study showed substantial diversity in the test tef germplasm. This revised version was published online in August 2006 with corrections to the Cover Date.     

Diversity for osmotic adjustment and root depth in TEF [Eragrostis tef (Zucc) Trotter]

Osmotic adjustment (OA) and deep roots were shown to be important drought resistance mechanism in many crop plants. In this study, geno types systematically selected from an Ethiopian endemic tef [Eragrostis tef (Zucc) Trotter] germplasm pool were evaluated for osmotic adjustment and root depth in greenhouse in several experiments. The association of these traits with other plant characters was also studied. Osmotic adjustment was investigated in two experiments. Experiment 1 was conducted using nine genotypes for two seasons (spring and fall 1996), and experiment 2 was undertaken in the spring of 1997 with 45 genotypes. In experiment 1, there were significant genotype effects on OA. Though there was also significant genotype by season interaction for OA, some of the extreme lines gave consistently high (Ada and DZ-01-99) and low (DZ-01-354 and Trotteriana) OA values across seasons. There was a significant variation among genotypes for OA in experiment 2. Osmotic adjustment was not associated with the altitude of the region of origin of the particular tef genotype. In both experiments, OA was significantly correlated across tef genotypes with delayed wilting and the maintenance of higher relative water content (RWC) under conditions of soil moisture stress. Three experiments were conducted to evaluate the phenotypic diversity for root depth. In all experiments tef genotypes differed significantly for root depth as measured at flowering time. The late maturing genotypes tended to have greater root depth as compared to early maturing genotypes. Root depth was not associated with the altitude of the region of origin of the tested genotypes. There was no association between root depth and OA across genotypes. This revised version was published online in August 2006 with corrections to the Cover Date.     

Heritability and genetic advance in recombinant inbred lines of tef (Eragrostis tef)

Recombinant inbred lines (RILs) of the tef cross Kaye Murri × Fesho were evaluated for nine quantitative traits at three locations in the central highlands of Ethiopia during the 1998/99 main season in order to estimate the genetic coefficient of variation (GCV), heritability and genetic advance expected from selection. Highly significant differences were obtained among the RILs for all traits studied. Grain yield, panicle weight and yield per panicle showed a relatively high GCV (12–16%). A comparatively high heritability was obtained from days to heading (31%) followed by panicle length (25%) and grain yield (23%). Moderate amounts of heritability values were obtained for panicle weight and yield per panicle. High genetic advance as percent of the mean were obtained from grain yield (16%), yield per panicle (12%) and panicle weight (10%) at5% selection intensity, which indicated the possibility of improving these traits. Several RILs were identified that have exceeded the better yielding parent at all locations. Grain yield showed a strong positive association (r = 0.26–0.70) with shoot biomass, lodging index, panicle length, plant height, panicle weight and yield per panicle. Overall, the present results showed a) the availability of genetic variance for some useful traits in the RILs for exploitation through selection, b) the existence of significant genotype × location interaction that indicated the need to test inbred populations in more environments, and c)the availability of superior inbred lines for further breeding work. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetics of grain yield and other agronomic characters in t'ef (Eragrostis tef Zucc Trotter). II. The triple test cross

The normal and selfed families of the triple test cross were employed to detect gene action in t'ef for grain yield and other useful agronomic characters in the breeding programme. Cultivars Kay Murri and Fesho were used as L₁ and L₂ testers, respectively. Eight randomly selected cultivars and two released varieties (DZ-01-354 and DZ-01-196) were crossed with the testers L₁, L₂ and L₃ (the F₁ of L₁ × L₂). In the case of the selfed families, 14 cultivars and two released varieties were used for crossing with the testers. The normal families were grown on an Inceptisol developed from volcanic ash whilst the selfed families were grown on a pellic Vertisol at the Debre Zeit Agricultural Research Centre, Ethiopia. The rainfall during the experimental season was 463 mm. Epistasis was detected for grain yield, yield per panicle, panicle weight, plant weight, harvest index, tiller number, panicle length, culm diameter, days to heading and days to maturity in the normal families of the triple test cross (TTC) of t'ef. Similarly the characters grain yield, yield per panicle, panicle weight, plant height, panicle length, days to heading and days to maturity showed epistasis in the selfed families of the TTC. Epistatic interaction was not important for shoot biomass and for harvest index (for the transformed data) in this family. Therefore, both the normal and selfed families of the TTC were in agreement with regard to detecting epistasis for grain yield, yield per panicle, panicle weight, panicle length, days to heading and days to maturity. Significant additive (D) and dominance (H) components were estimated for the characters in both families, although the magnitudes might have been inflated due to epistasis. The dominance component for panicle length was unimportant in both families of the TTC and as a result the additive components were not biased. In general, the additive, dominance and epistatic components were important in t'ef. Since the crop is self-fertilized only the additive and additive × additive terms are important to develop pure breeding varieties. Therefore, selection for superior segregants should start in advanced generations as homozygosity increases. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetics of grain yield and other agronomic characters in t'ef (Eragrostis tef Zucc. Trotter). I. Generation means and variances analysis

Quantitative genetics of grain yield and other agronomic characters of t'ef (Eragrostis tef) were studied using the F₁, F₂, BC₁, and BC₂ of the cross Fesho × Kay Murri. The study was carried out to estimate gene effects controlling the inheritance of grain yield and related agronomic characters. Significant additive [d] and dominance × dominance [l] interaction effects were detected for grain yield. The variations of yield per panicle and panicle weight were explained in terms of [d], dominance [h], and additive × additive [i] interactions. Non-allelic gene interactions were also detected for kernel weight, harvest index, tiller number, plant height, days to heading and days to maturity. The simple additive-dominance model explained the variation for panicle length, culm diameter and plant weight, allowing unbiased estimates of additive (D) and dominance (H) variance components. Large dominance variances (H) were estimated for grain yield, yield per panicle, and panicle weight. The additive variances for plant height, panicle length, days to heading and days to maturity were higher than the respective dominance variances. High narrow-sense heritability (h²) values (> 0.50) were estimated for plant height, panicle length, days to heading and days to maturity. The lowest h² (0.09) was obtained for kernel weight for which there was little variability. Since grain yield and several important agronomic characters of t'ef are influenced by non-allelic gene interaction, it is advisable to delay selection for yield to later generations with increased homozygosity. This revised version was published online in July 2006 with corrections to the Cover Date.     

Smoke-Water and a Smoke-Isolated Butenolide Improve Germination and Seedling Vigour of Eragrostis tef (Zucc.) Trotter under High Temperature and Low Osmotic Potential

The seeds of Eragrostis tef are often exposed to high temperatures and low water availability during unfavourable climatic conditions. This affects germination and seedling stand establishment of the crop. Smoke is currently widely studied for its stimulatory role in seed germination. The effect of smoke-water and a smoke-isolated butenolide was investigated on E. tef seed germination and seedling growth at different temperatures, light conditions and osmotic potentials. Treating E. tef seeds with smoke-water and butenolide increased the percentage germination relative to the control at all tested temperatures. These treatments significantly improved seedling length and the vigour index at 25, 30, 35 and 40 and 30/15 °C. Smoke-water and butenolide increased percentage imbibition from high to low osmotic potential. In comparison with the control, smoke-water- and butenolide-treated seeds of E. tef showed higher percentage germination with decreasing osmotic potential. Smoke-water treatment exhibited significantly longer and more vigorous seedlings than the control between 0 and −0.30 MPa osmotic potential. The findings of this study suggest the possibility of using smoke treatments for minimizing E. tef seedling losses at elevated temperatures and water stress.     

Phosphorus Response Studies on Some Varieties of Durum Wheat (Triticum durum Desf.) and Tef (Eragrostis tef (Zucc.) Trotter) Grown in Sand Culture

The response of four varieties each of durum wheat (DZ-04-118, DZ-320, DZ-918 and TOB-2) and tef (DZ-01-354, DZ-01-787, DZ-01-1445, and DZ-Cr-37) to P application levels was examined in a sand culture study conducted in a glasshouse for 4 weeks. Results showed that plant height, shoot and root dry weights, and plant P uptake were increased by increasing levels of P application from 0 to 5 (tef) and 0 to 10 mg P 100 g⁻¹ (wheat). Varietal differences were also observed in all parameters, except in shoot dry weight of the four durum wheat varieties. In general, all modern varieties of the two crops showed better growth and P uptake than the corresponding traditional varieties. The short period study proved that variations generally existed in the P responses of durum wheat and tef varieties which may be confirmed by long-term study up to maturity. Inclusion of more populations in similar studies may help to identify P efficient genotypes.     

Genetic diversity in tef [Eragrostis tef (Zucc) Trotter] and its relatives as revealed by Random Amplified Polymorphic DNAs

Tef is one of the staple cereal crops in Ethiopia. To evaluate genetic diversity of tef and its relatives, 47 accessions of tef, three accessions of E. pilosa, and six accessions of E. curvulawere analyzed using random amplified polymorphic DNA (RAPD) markers. The level of polymorphism among the wild species was extremely high, while low polymorphism was detected among tef accessions. All cultivars and wild species under study could be distinguished with the help of different primers, thereby indicating the potential of RAPD in the genetic fingerprinting of tef. Accessions from E. curvula and E. pilosa can be differentiated by a single selected primer. In spite of low polymorphism within tef, accessions under study could be distinguished by a combination of selected primers. Cluster analysis indicated that tef is a very closely related species to E. pilosa with 45%similarity, supporting the hypothesis that tef originated from E. pilosa based on morphological data. Given that RAPD are relatively quick, simple to use, and are not subjected to environmental influences, they provide a valuable new approach for the genetic fingerprinting and study of genetic diversity in tef. This revised version was published online in July 2006 with corrections to the Cover Date.     

Gene action controlling yield and yield‐related traits among tef (Eragrostis tef [Zucc.] Trotter) populations under drought‐stressed and nonstressed conditions

This study was aimed to determine gene action for grain yield and yield‐related traits of newly developed tef populations under drought‐stressed and nonstressed conditions to improve drought tolerance. Ten crosses, along with the parents, were evaluated in the F₂ generation under drought‐stressed conditions at Hastebo and Adigdad sites in 2015 and Dura site in 2016 and under nonstressed conditions at Dura site in 2016. Additive gene action predominantly controlled the inheritance of the grain yield and majority of the yield‐related traits under drought‐stressed and nonstressed conditions. Under both test conditions, the genotypes DZ‐Cr‐387 and 9415 were the best general combiners for increased grain yield and morphological traits. Conversely, genotype 222076 was the best general combiner for reduced maturity period only. The selected parents are novel genetic materials for tef breeding programmes to improve grain yield and morphological traits with reduced days to maturity for drought tolerance breeding. The family of the cross DZ‐Cr‐387 × 222076 was selected for high grain yield and early maturity in both the drought‐stressed and nonstressed environments.     

Evaluation of Drought Tolerance in Tef [Eragrostis Tef (Zucc.) Trotter] Genotypes Using Drought Tolerance Indices

Journal of Crop Science and Biotechnology - A field experiment was conducted to identify drought tolerant, high yielding and stable tef genotypes using drought tolerance indices. Sixty-four tef...     

Genetic diversity of garlic (Allium sativum L.) germplasm from China by fluorescent‐based AFLP,SSR and InDel markers

Garlic (Allium sativum L.), an asexually propagated crop, is an important vegetable and medicinal plant. China is the biggest garlic producer in the world; however, the genetic background of garlic from China is not well understood. In this study, population structure and clustering analysis of garlic germplasm was performed using amplified fragment length polymorphism (AFLP), simple sequence repeat (SSR) and insertion–deletion (InDel) markers. Among 212 accessions of garlic, genetic diversity analysis identified 546 alleles amplified by AFLP, SSR and InDel primers, and 492 of these were polymorphic. All accessions were divided into five groups by structure analysis and neighbor‐joining clustering. Most traits, including allicin content, were only slightly affected by population structure, which indicated that this germplasm can be used as populations for association mapping. The results provide a molecular basis for understanding the genetic diversity of the garlic germplasm preserved in China.     

澳洲坚果种质资源形态性状的遗传多样性分析

为了解引入澳洲坚果种质的遗传背景,以64份澳洲坚果种质为试材,采用41个形态性状对其进行了遗传多样性分析。41个形态性状的差异性和R型聚类分析结果表明：各性状间差异达到极显著水平;在欧氏距离（D）≈11.72处,41个性状聚为两组,组内各性状的欧氏距离较远,绝大多数性状间相对独立,对澳洲坚果种质的演化各具独立的意义,在澳洲坚果的分类中有较好的分辨能力。Q型聚类分析结果表明：64份种质的欧氏距离在3.15~12.39之间,具有较高的遗传多样性。在D≈12处可将64份种质划分为二个类群：第一类群仅包含T2 1份种质,为澳洲坚果栽培种的近缘种;第二类群包含剩下的63份种质,为澳洲坚果的栽培种。第二类群在D≈10处,可细分成3个亚类：第Ⅰ亚类包括7份种质（即695、Tet.-2、900、D4、HY、Tet.-1和广9）,属于粗壳种与光壳种的杂交种;第Ⅱ亚类包括A4和A16两个品种,属于粗壳种与光壳种的杂交种,但更偏重于光壳种;第Ⅲ亚类包括其他54份种质,都是光壳种的后代。获得的聚类结果与现有的分类体系一致;同时,获得了64份种质的形态性状聚类的亲缘关系图,其在生产种植中的品种搭配、育种中的杂交亲本选择和引种方面都具有指导意义。     

Study of genetic diversity in Indian and exotic sesame (Sesamum indicum L.) germplasm using random amplified polymorphic DNA (RAPD) markers

Fifty-eight accessions of sesame (Sesamum indicum L.), an important oil seed crop of the tropics and subtropics were analysed using random amplified polymorphic DNA (RAPD) technique. The material analysed comprised 36 collections from 18 different states of India and four adjoining countries of the Indian subcontinent, and 22 exotic accessions from 21 sesame growing countries around the world. The results from PCR amplifications with the selected 24 random 10-mer primers were statistically analysed. The value of Jaccard’s similarity coefficients ranged from 0.19 to 0.89. The results indicated the presence of high level of genetic diversity. However, the extent of genetic diversity was greater in the collections from Indian subcontinent as compared to the exotics. Among the Indian accessions, the collections from Rajasthan and North-eastern states were highly diverse. The phenetic analysis grouped 48 out of 58 accessions in six clusters and the remaining highly diverse accessions were placed outside these close-knit clusters. The Bootstrap estimates obtained by Wagner parsimony analysis were significant for seven out of 49 nodes in the majority-rule consensus tree (<95% occurrence). The results of both the analyses were, however, broadly comparable when the constitution of the individual clusters were considered. The principal components analysis indicated that the first two components accounted for only 21% of the total variations and in order to explain <75% of variations 18 components were required. The high level of genetic diversity prevalent among the Indian collections is probably indicative of the nativity of this crop species. Similarly, the relatively lower level of polymorphism in exotic germplasm could be ascribed to the comparatively recent introductions of limited germplasm of this crop into some of the non-traditional sesame growing countries. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic diversity and differentiation of Chinese wild soybean germplasm (G. soja Sieb. & Zucc.) in geographical scale revealed by SSR markers

Wild soybean (Glycine soja), as the progenitor of soybeans (G. max), is widely distributed in China and has been collected as a supplementary germplasm pool of soybeans. In this study, 375 wild soybean accessions from a set of genebank core collection were analysed for genetic diversity by using 42 simple sequence repeat primer pairs. The mean allele number per locus was 19.62. Ten‐percent unique alleles involving 35 or 83.33% loci differentiated among the geographical regions. The mean gene diversity (h) per locus was 0.89. A very low mean coefficient of gene differentiation (G_ST = 0.08) for geographical regions and a high mean within‐region gene diversity (H_S = 0.81) were observed, indicating that most genetic diversity existed within the regions. There was an obvious relationship between genetic distance and geographical distance. The results showed multiple centers of genetic diversity for Chinese wild soybean in North China, the Huanghe River Valley, and Central China as well as the Changjiang River Valley, implicating multiple site origins of soybeans within China.     

Quantitative-genetic parameters of sorghum [Sorghum bicolor (L.) Moench] grown in semi-arid areas of Kenya

Low and erratic rainfall constitutes a major constraint to sorghum production, and impedes sorghum improvement in semi-arid tropics. To estimate quantitative-genetic parameters for sorghum under variable stress conditions, three sets of factorial crosses between four by four lines each were grown with parents and a local cultivar in eight macro-environments in semi-arid areas of Kenya. Fourteen traits were recorded including grain yield, above-ground drymatter, harvest index, days to anthesis, leaf rolling score, and stay-green. Environmental means for grain yield ranged from 167 to 595 g m-2. Mean hybrid superiority over mid-parent values was 47, 31, and 9% for grain yield, above-ground drymatter, and harvest index, respectively. Differences among both lines and hybrids were highly significant for all traits. Genotype × environment interaction variances were larger than genotypic variances for grain yield, above-ground drymatter, and harvest index. Corresponding heritabilities ranged between 0.72 and 0.84. Variation among hybrids was determined by GCA and SCA effects for most characters. Predominance of additive-genetic effects was found for grain yield components, plant height, and leaf rolling score. Lack of variation in GCA was noted among female lines for major performance traits. While low leaf rolling score was correlated with high grain yield, there was no such association for stay-green. Hybrid breeding could contribute to sorghum improvement for semi-arid areas of Kenya. To increase selection progress for major performance traits, genetic variation among female lines should be enhanced. Importance of genotype × environment interaction underlines the necessity of evaluating breeding materials under a broad range of dryland conditions.