Inheritance of black testa colour in lentil (Lens culinaris Medik.)

The inheritance of testa (seed coat) colour and interaction of cotyledon and testa colours were studied in seven crosses of lentil (Lens culinaris Medik.) involving parents with black, brown, tan or green testa and with orange, yellow or dark green cotyledons. Analysis of F₂ and F₃ seed harvested from F₁ and F₂ plants, respectively, revealed that although black testa is dominant over nonblack testa, its penetrance is not complete since both F₁ plants and heterozygous F₂ plants produced varying proportions of seeds with either black or nonblack testa. The F₂ populations of the crosses between parents with brown and tan, as well as brown and green, testa segregated in the ratio of 3 brown : 1 tan and 3 brown : 1 green, respectively, indicating monogenic dominance of brown testa colour over tan or green. The expression of testa colour was influenced by cotyledon colour when parents with brown or green testa are crossed with those having orange or green cotyledons. Thus F₂ seeds from these crosses with a green testa always had green cotyledons and never orange cotyledons. F₂ seeds from these crosses with a brown testa always had orange cotyledons and never green cotyledons. These results suggest diffusion of a soluble pigment from the cotyledons to the testa. This revised version was published online in July 2006 with corrections to the Cover Date.     

Association of isozyme markers with quantitative trait loci in random single seed descent derived lines of lentil (Lens culinaris Medik.)

Summary Polymorphism at isozyme loci was used to locate factors responsible for variation in quantitative traits of lentil. Eight sets of random single seed descent (RSSD) derived lines were developed by advancing individual F₃ plants of interspecific (L. culinaris Medik. × L. orientalis Boiss.) hybrids to the F₆. The RSSD lines in each of the eight sets differed for alleles at 2–8 isozyme loci. In each set, association of isozyme loci with variation in seven quantitative traits (days to flower, days to mature, plant height, biomass, seed yield, harvest index, seed weight) was determined for each pairwise combination of a quantitative trait with a marker locus. Loci affecting variation in all seven quantitative traits were detected by their association with 14 isozyme markers (Aat-c, Aat-m, Aat-p, Adh-1, Fk, Gal-1, Gal-2, Lap-1, Lap-2, Pgd-p, Pgi, Pgm-c, Pgm-p, Skdh). The known position of 10 the 14 isozyme loci on the lentil genetic map was used to mark the genomic regions for possible location of associated quantitative trait loci (QTL). Detected QTL were found to be located in six of the seven linkage groups on lentil genetic map. Regions of the genome represented by linkage groups, 1, 5 and 7 appeared to affect a greater number of traits than other genomic regions represented by linkage groups 2, 3 and 4. Results indicated that the mean expression of quantitative traits at segregating marker locus classes can be used to locate the genetic factors in lentil which influence the behavior of economically important traits.     

Inheritance of resistance to Fusarium wilt in Indian lentil germplasm (Lens culinaris Medik.)

Summary Three lentil genotypes resistant to Fusarium oxysporum f.sp. lentis viz. Pant L 234, JL 446 and LP 286 were crossed with two susceptible ones. The hybrid plants were all resistant in the eight crosses evaluated. Segregation pattern for wilt reaction in F₂, BC(P₁), BC(P₂) and F₃ generations in field and glasshouse conditions indicated that resistance to Fusarium wilt is under the control of two dominant duplicate genes in Pant L 234 and two independent dominant genes with complementary effects in JL 446 and LP 286. A third dominant gene complementary to the dominant genes in JL 446 and LP 286 is present in two susceptible lines. Allelic tests suggest the presence of five independently segregating genes for resistance. Duplicate dominant genes in Pant L 234 are non-allelic to two dominant genes with complementary effects in LP 286 and JL 446 and the third gene complementary to the two genes in JL 446 and LP 286 in susceptible lines JL 641 and L 9–12. Gene symbols among parental genotypes have been designated.     

Discovery of a new gene causing dark green cotyledons and pathway of pigment synthesis in lentil (Lens culinaris Medik)

A new gene is reported which functions as a master gene for synthesis of the pigments determining cotyledon colour in lentil. This gene is different from the two earlier reported genes which are responsible for synthesis of yellow (gene Y) and brown (gene B) pigments. Double recessive homozygous condition of these two genes results into loss of both pigments and, consequently, produces light green cotyledons. The new gene, in contrast, produces dark green cotyledons in recessive condition irrespective of the dominance or recessive state of the Y and B genes. It is hypothesized that the new gene for dark green cotyledon colour (Dg) acts at an earlier stage in the biosynthesis of the two cotyledon-specific pigments, which are derived from a common precursor, whose synthesis is blocked when Dg mutates to its recessive condition. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic variance of six agronomic characters in three lentil (Lens culinaris Medic) crosses

Summary Three lentil (Lens culinaris Medic) crosses (cross 1 = Chilean × PI 297784; cross 2 = Tekoa × PI 212611; cross 3 = Precoz × PI 212611) were advanced in a hierarchal design from the F₂ generation to the F₅ generation and tested in replicated field experiments. The purpose was to estimate the genotypic variances and covariances for several characters and to partition these into components due to additive, dominance, and additive × additive variances.Additive genetic variance was the major component of variance in cross 2 for all characters, except plant height and seed weight. Unexpectedly, estimates of dominance variance appeared to be high in crosses 1 and 3. Estimates of the additive × additive component seemed very small in all three populations. The dominance variance component estimates were consistently high for plant height in the three crosses and for seed weight in crosses 2 and 3. Where parental means were close, additive variance estimates were often low and in many cases negative. The unexpected high ratio of dominance variance to additive variance indicated that dominance variance was important in the crosses we studied.Cooperative investigations of Agricultural Research Service, US Department of Agriculture and the College of Agriculture, Washington State University, Pullman, Washington 99164, Work sponsored by Fellowship from Univ. of Jordan, Amman, Jordan. Scientific paper no. 5825.Formerly: Department of Agronomy and Soils, Washington State University, Pullman, WA., USA. Presently: Department of Plant Production and Plant Protection, University of Jordan, Amman, Jordan.Statistical Services, Washington State University, Pullman, WA 99164, USA.US Department of Agriculture, Agricultural Research Service, Washington State University, Pullman WA 99164, USA.     

Genetics of seed coat colour in lentil

Summary Four grey mottled seed coat colour lentil lines/cultivars were crossed to one brown seed coat colour cultivar. The F₁ hybrids were brown seeded in all the crosses. Segregation pattern for seed coat colour in F₂ and F₃ generations revealed that it is under control of a single dominant gene, which is present in the parent UPL 175 while a recessive gene is responsible for grey mottled seed coat colour in Pant L 406, Pant L 639, LG 120 and Rau 101.     

Harvest index in lentil (Lens culinaris Medik.)

Summary Correlation and path coefficient analyses were conducted to find out the characters associated with grain yield and dry matter production and the ways to improve harvest index in lentil.Correlation studies revealed positive association of harvest index with grain yield but no association with plant dry matter. Grain yield and plant dry matter showed positive correlation with pod number, plant height, and number of primary and secondary branches but negative correlation with 100-seed weight. Generally, the genotypic correlations were in agreement with phenotypic correlations, though the magnitude of the values was higher in the former case. In path analysis, plant height and pod number showed the highest direct effect and, therefore, seem to be the main characters influencing grain yield and plant dry matter. Number of primary and secondary branches, on the other hand, showed negative direct effect on grain yield and plant dry matter. Use of phenotypic or genotypic correlations in path analysis resulted in similar conclusions. It is, therefore, suggested that either phenotypic or genotypic correlations may be used in path analysis with equal efficiency. Based on this study it is suggested to develop tall varieties with good pod bearing but with low number of branches.     

Relationships among economic characters in lentil

Summary There are several reports of the association among lentil characters based on a few, relatively similar lines grown in single environments. Their results have often been inconsistent because of inadequate sampling of genotypes and environments. This study examined associations between economic characters in lentil over a wide range of genetic material and environments in West Asia. The first part of the study concerned correlations within large samples from the world lentil collection grown in two seasons, and the second part covered a smaller sample of genetic material from the collection sown over a wider range of conditions.The results showed similar phenotypic correlations over two seasons, contrasting in rainfall, in the world lentil collection. Similar genetic and phenotypic correlations were also shown by the smaller sample of germplasm over 10 environments. These results indicated low importance of covariance due to environmental and genotype-environment interaction effects. Seed yield was positively correlated with straw yield, indicating selection for either character will increase the other trait. The correlation between seed protein content and seed yield was small and negative, while the correlation of protein with straw yield was positive in sign. This suggests that the current ICARDA goals of selection for high seed and straw yield will not have a major correlated effect on seed protein content. There was a strong positive correlation between seed size and cooking time (r=0.96), therefore seed size can be used to predict cooking time.     

Single plant selection for yield in lentil

Summary Individual plant selection for yield in lentil is problematic at a commercial crop density primarily because of inter-plant entanglement by tendrils. Visual plant selection for yield was compared with random selection in the F₅ at three plant densities (66, 133 and 200 seeds/m²) by an evaluation of F₇ progeny yields over two seasons in two populations of lentil. Random plant sampling was as effective as visual plant selection in isolating high-yielding F₇ lines. The plant density of the selection environment did not affect the response to selection. The correlations between the seed number of selected F₅ plants and the mean yield of their F₇ progenies were r=+–0.26 and –0.06 in two populations, indicating the lack of positive response to plant selection for seed number. The results show that 1) random sampling is the most economic of the methods tested of plant selection for yield and 2) the plant density of the environment for plant selection can be low enough to avoid inter-plant entanglement by tendrils, allowing a focus in plant selection on characters, other than yield, of importance to the breeding program and with a higher heritability than yield.     

Genetics of allozyme variants and linkage groups in lentil

Summary The genetics of 8 electrophoretically detectable enzymes in lentil was examined. The enzyme systems glutamic-oxaloacetic transaminase, malic enzyme, phosphoglucomutase, alcohol dehydrogenase, 6-phosphogluconate dehydrogenase, shikimic dehydrogenase and isocitrate dehydrogenase were assayed. The allozymes at each of the studied loci behaved in a codominant manner and segregated in the expected Mendelian fashion. Linkage tests between these loci and an additional morphological trait revealed two linkage groups that involved 5 loci, the rest were independent of each other.     

Geographic distribution of variation in quantitative traits in a world lentil collection

Summary In a world lentil collection the distribution of variation amongst accessions from 13 major lentil-producing countries was examined on the basis of nine quantitative morphological characters by discriminant analysis and canonical analysis. Stepwise discriminant analysis revealed major differences between accessions from different countries. Three major regional groups were apparent: 1) a levantine group (Egypt, Jordan, Lebanon and Syria, 2) a more northern group composed of Greece, Iran, Turkey, and USSR, and 3) accessions from India and Ethiopia with strikingly similar quantitative morphological characters. Misclassifications of individuals within groups were frequent. Characters useful in discriminating between accessions from different countries were in descending order of importance: time to maturity, lowest pod height and 100-seed weight. The regional grouping indicates the importance of local adaptation through clusters of associated characters with phenological adaptation to the ecological environment as the major evolutionary force in the species.     

RAPD and SCAR markers for resistance to acochyta blight in lentil

Resistance to ascochyta blight of lentil (Lens culinaris Medikus),caused by the fungus Ascochyta lentis, is determined by a single recessive gene, ral ₂, in the lentil cultivar Indian head. Sixty F₂ individuals from a cross between Eston (susceptible) and Indian head (resistant) lentil were analyzed for the presence of random amplified polymorphic DNA (RAPD) markers linked to the ral ₂gene, using bulked segregant analysis (BSA). Out of 800 decanucleotide primers screened, two produced polymorphic markers that co-segregated with the resistance locus. These two RAPD markers, UBC227₁₂₉₀and OPD-10₈₇₀, flanked and were linked in repulsion phase to the gene ral ₂ at 12 cm and 16 cm, respectively. The RAPD fragments were converted to SCAR markers. The SCAR marker developed from UBC227₁₂₉₀ could not detect any polymorphism between the two parents or in the F₂. The SCAR marker developed from OPD-10₈₇₀ retained its polymorphism. The polymorphic RAPD marker UBC227₁₂₉₀ and the SCAR marker developed from OPD-10₈₇₀ can be used together in a marker assisted selection program for ascochyta blight resistance in lentil. This revised version was published online in July 2006 with corrections to the Cover Date.     

Variation between and within lentil landraces from Yemen Arab Republic

Summary The variation in 31 landraces of lentil collected from Yemen Arab Republic was partitioned to estimate the variation between populations and the variation between families within populations by studying a total of 568 progenies of randomly selected plants. There was significant variation between populations and between families within populations in seedling pigmentation, time to flower, time to maturity and plant height, but the predominant source of variation was between populations. This variation was unrelated to altitude of collection. The landraces were equally variable across characters. The implications of this analysis of variation on lentil breeding and germplasm collection are discussed.     

Using molecular markers to pyramid genes for resistance to ascochyta blight and anthracnose in lentil (Lens culinaris Medik)

Ascochyta blight caused by the fungus Ascochyta lentis Vassilievsky and anthracnose caused by Colletotrichum truncatum [(Schwein.) Andrus & W.D. Moore] are the most destructive diseases of lentil in Canada. The diseases reduce both seed yield and seed quality. Previous studies demonstrated that two genes, ral1 and AbR1, confer resistance toA. lentis and a major gene controls the resistance to 95B36 isolate of C. truncatum. Molecular markers linked to each gene have been identified. The current study was conducted to pyramid the two genes for resistance to ascochyta blight and the gene for resistance to anthracnose into lentil breeding lines. A population (F_6:7) consisting of 156 recombinant inbred lines (RILs) was developed from across between ‘CDC Robin’ and a breeding line ‘964a-46’. The RILs were screened for reaction to two isolates (A1 and 3D2) ofA. lentis and one isolate (95B36) ofC. truncatum. χ² analysis of disease reactions demonstrated that the observed segregation ratios of resistant versus susceptible fit the two gene model for resistance to ascochyta blight and a single gene model for resistance to anthracnose. Using markers linked to ral1 (UBC 227₁₂₉₀), to AbR1(RB18₆₈₀) and to the major gene for resistance to anthracnose (OPO6₁₂₅₀),respectively, we confirmed that 11 RILs retained all the three resistance genes. More than 82% of the lines that had either or both RB18₆₈₀ and UBC227₁₂₉₀markers were resistant to 3D2 isolate and had a mean disease score lower than 2.5. By contrast, 80% of the lines that had none of the RAPD markers were susceptible and had a mean disease score of 5.8. For the case of A1 isolate of A. lentis, more than 74% of the lines that carriedUBC227₁₂₉₀ were resistant, whereas more than 79% of the lines that do not have the marker were susceptible. The analysis of the RILs usingOPO6₁₂₅₀ marker demonstrated that 11out of 72 resistant lines carried the marker, whereas 66 out of 84 susceptible lines had the marker present. Therefore, selecting materials with both markers for resistance to ascochyta blight and a marker for resistance to anthracnose can clearly make progress toward resistance in the population. This revised version was published online in July 2006 with corrections to the Cover Date.     

Restoration of meiotic regularity and fertility among derivatives of Lens culinaris x L. Nigricans hybrids

Summary The wild lentil, L. nigricans is cross compatible with the cultivated species. Chromosome pairing in their F₁ hybrids is highly irregular due to a difference of three translocations between the parental species. However, the hybrids are partially fertile and in the F₂ populations there is a marked improvement in fertility. About 19% of the F₂ plants were meiotically stable, fully fertile and their chromosome arrangement was similar to that of the cultivated species. All these are clear indications for the possibility of rapid introgression between the two species and hence systematic screening of L. nigricans for traits of economic value is fully justifiable.     

Comparison of random bulk population and single-seed-descent methods for lentil breeding

Summary Three lentil (Lens culinaris Medic.) populations were advanced from the F₂ to the F₄ generation by singleseed-descent (SSD) and bulk-population (BP) breeding methods and used to compare the relative efficiency of the methods for maintaining genetic variation and selection opportunities.SSD maintained more genetic variation (% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqbeo8aZzaaja% Waa0baaSqaaiaadEgaaeaacaaIYaaaaaaa!3B04!\[\hat \sigma _g^2 \]) in 15 of 21 comparisons of characters that were made. Genetic variances were significantly higher with SSD for plant height, days to maturity and yield in population 1; height of lowest pod in population 2; and days to blooming, height of lowest pod, plant type, and yield in population 3. SSD-derived populations had 10, 9, and 13% more erect lines in the three populations, respectively, when compared to the same populations advanced by BP. The BP method maintained 14, 2, and 4% more taller types in the three populations, respectively, and 16 and 33% more segregants that carried their pods higher from the ground. This indicated a reduced frequency of short plants with low flowers as a result of natural selection operating within BP against less competitive short types. The SSD method is an efficient cost-saving method of advancing lentil populations and is recommended for lentil breeding.Scientific Paper No. 5478.     

Determination of genetic variation and taxonomy in lentil (Lens Miller) species by chloroplast DNA polymorphism

Summary Chloroplast DNA restriction fragment lenght polymorphisms (RFLP) were used to examine the taxonomic relationships of cultivated and wild lentil (Lens Miller) species and identify the extent of genetic variation in this genus. Twelve accessions representing all Lens subspecies were digested with four hexanucleotide-recognizing restriction endonucleases. These digests randomly surveyed 540 base pairs, or 0.4% of the approximately 125 kilobase lentil chloroplast genome. A high degree of gragment length conservation was seen among members of crossability group I, i.e., L. c. ssp. culinaris, L. c. ssp. orientalis and L. c. ssp. odemensis. Accessions of the two subspecies comprising crossability group II, i.e., L. n. ssp. nigricans and L. n. ssp. ervoides, showed the greatest amount of variation when compared to the cultivated lentil, L. c. ssp. culinaris. Limited variation was observed within subspecies except for L. n. ssp. nigricans, where accessions of the normal cytotype were highly polymorphic to those of the differentiated cytotype. Chloroplast DNA RFLPs reaffirm hypotheses that propose L. c. ssp. orientalis as the progenitor to the cultivated lentil. The implications of this study on taxonomy and genetic resources is also discussed.     

A bottleneck in lentil: widening its genetic base in South Asia

This paper introduces the concept of a bottleneck in lentil (Lens culinaris Medikus) in South Asia and then reviews its rupture. South Asia is the largest lentil growing region in the world and where indigenous lentils show a marked lack of variability. This results from its introduction from Afghanistan around 2000 B.C. and it limits breeding progress. Three approaches to widening the genetic base in the region have been tried, namely plant introduction, hybridization and mutation breeding. Introductions from West Asia flower as indigenous material matures. The asynchrony in flowering has isolated the local pilosae ecotype reproductively. However, the introduction of ILL 4605, an early, large-seeded line, has resulted in its release as ‘Manserha 89’ for wetter areas of Pakistan and its widespread use as a parent in breeding programs in the region. Hybridization between pilosae and exotic germplasm, primarily at International Center for Agricultural Research in the Dry Areas (ICARDA) followed by selection in the sub-continent has resulted in cultivars with improved disease resistance and yield in Bangladesh and Pakistan. Mutation breeding has given new morphological markers and several promising lines. These examples illustrate not only the widening of the genetic base of the lentil in South Asia, but also the evolution of a breeding program of an international center and national programs targeted toward specific adaptation. This revised version was published online in July 2006 with corrections to the Cover Date.     

The origin of lentil and its wild genepool

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

Response to conventional and organic environment of thirty-six lentil (<Emphasis Type="Italic">Lens culinaris</Emphasis> Medik.) varieties

Thirty-six lentil varieties were evaluated under organic and conventional environment for three consecutive years in order to see whether the promising genetic material for an organic plant breeding program are different from those of a conventional system. The genetic material studied originated from various countries. In the conventional trial plots standard cultural practices (P mineral fertilization & pest control) were applied throughout the growing season, while in the organic ones no fertilizers or pest agrochemicals were applied. Significant regression, but of low value, between grain yield ranking and earliness or harvest index ranking was detected. Combined ANOVA indicated significant differences between genotypes, years, environments and genotype × environmental interactions (GEI). It was observed that under conventional management most of the genotypes had a higher yield compared to the organic one. The mean grain yield ranking of the genotypes in each of the environments revealed that some of the genotypes occupied the same ranking position at both the organic and the conventional environment (non-crossover GEI), while others exhibited a significant alteration in their ranking (crossover GEI) under the two environments. Crossover GEI and non-cross over GEI revealed two types of lentil varieties. Varieties with specific adaptation and varieties with broad adaptation. It was concluded that grain yield was in general higher when lentil varieties were grown under a conventional environment compared to the grain yield produced under an organic environment. Yet, there are lentil genotypes with a higher yielding ability under the organic management and therefore should be targeted by the breeder.