Phenotypic and Genotypic Characterization of Grass pea (Lathyrus sativus L.) Accessions Collected from North-Western Ethiopia Using Molecular and Morphological Markers
Creators: name: Desalegn Abebe Mekonen
Publisher: name: National Academic Digital Repository of Ethiopia
Year: 2020
Subjects: Grass pea (Lathyrus sativus); β-ODAP, SSR, genetic parameter, traits association, PIC, gene diversity

description: Grass pea (Lathyrus sativus L.) is an important legume crop used as food, feed, and fodder. It is rich<br> in protein compared to other legume crops. Despite its importance, it has a serious drawback of<br> having anti-nutritional β-ODAP content that causes neuro lathyrism disease that cripples the legs of<br> humans and animals. Limited research attention has been given to grass pea in Ethiopia and,<br> therefore, this study was undertaken to evaluate morpho-agronomic performance accessions and<br> identify those with low β-ODAP content; assess the magnitude of genetic diversity within the grass<br> pea accessions using SSR and morpho-agronomic markers; assess the extent of genetic variability,<br> broad-sense heritability and expected genetic gain from selection; and determine the magnitudes of<br> association among characters in grass pea accession among characters in the grass pea accessions<br> both at phenotypic and genotypic levels. Twenty-five grass pea accessions from the Ethiopian<br> Biodiversity Institute were evaluated for morpho-agronomic traits and β-ODAP content of seeds at<br> Ebonyi State University, CAS campus, Abakaliki, Nigeria. The experiment was conducted under field<br> conditions in the rainy season of 2019 using simple lattice design with, two replications. The genetic<br> diversity study was carried out using 10 pairs of SSR markers in IITA, Ibadan, Nigeria. All<br> quantitative morpho-agronomic traits and β-ODAP content of the seed showed highly significant at<br> (p&lt;0.01) differences except for petiole length which showed a non-significant difference. Days of<br> emergency were also significantly at (p&lt;0.05) different among the accessions. The β-ODAP content<br> of the seed ranged from 0.17 to 0.90 % with an average of 0.44 %. Two accessions, namely (238945<br> and 26627), showed the lowest seed β-ODAP content (0.17 and 0.185 in that order) within the safe<br> range for human consumption. Considerable amounts of genetic variability were observed among<br> accessions for potential exploitation in future grass pea improvement. High genotypic and<br> phenotypic coefficients of variation, heritability, and genetic advance as percent of mean were found<br> for the number of secondary branches, the number of branches per plant, β-ODAP content, length of<br> branch bearing, primary branch number, days to flowering, plant height and primary branch length.<br> Genotypic as well as the phenotypic association between β-ODAP content and all morphoagronomic traits showed no significant correlation except for leaf width which was highly<br> significant or significant but negative at phenotypic and genotypic levels. The accessions were<br> grouped into three clusters based on morpho-agronomic data, β-ODAP content, and microsatellite<br> loci. Clusters II and III showed lower seed β-ODAP content. The clustering pattern revealed that<br> accessions from different zonal origins were grouped in the same cluster or vise-versa, indicating<br> the existence of gene flow and seed interchange among farmers in different zones. The principal<br> component analysis showed that the first three principal components accounted for 76% of the total<br> variation. From the eight pairs of polymorphic SSR primers used to study genetic diversity among<br> the grass pea population, a total of 41 alleles were detected with an average of 5.13 alleles per<br> primer. The polymorphic information content for eight pairs of primers ranged from 0.074 to 0.941<br> with an average of 0.474. Gene diversity values ranged from 0.077 for primer G19207 to 0.944 for<br> primer G17 with a mean value of 0.536. The largest pairwise genetic distance (0.365) was detected<br> between the population from North Gondar and East Gojam population, while the smallest value<br> (0.033) was recorded between North Gondar and South Gondar. ФPT (analogs of Fst test) estimated<br> through analysis of molecular variance were 0.24, 0.20, and 0.05 for within accessions, among<br> zones, and among the population within zones respectively. The highest genetic differentiation value<br> (76 %) resides within accessions followed by 20 % among zones and the lowest or insignificant<br> genetic differentiation value (4 %) among the population within zones. Overall, moderate levels of<br> genetic diversity values were revealed by microsatellite loci among the studied accessions.