Genetic diversity in the germplasm of tropical maize landraces determined using molecular markers

Ecotype-Level Genetic Biodiversity of Five Italian Traditional Crops

Italy displays a high level of agrobiodiversity due to its diversified pedoclimatic zones. The Administrative Region of Campania includes several and divergent biomes, occurring close to each other. In fact, the distance between a sea level environment and that of high mountains can be less than 20 km. These environmental conditions allow the cultivation of many different crops and vegetables, represented by diverse ecotypes and varieties that are well adapted to the distribution range where they have been selected and grown. Efforts to maintain and further increase biodiversity in farming systems require a better understanding of the existing diversity created by traditional farming practices. The aim of our study was to identify and molecularly characterize several ecotypes belonging to five horticultural species commonly cultivated in Campania. In particular, we analysed five ecotypes of maize, two of garlic, four of onion, one of escarole, and two of courgette by means of simple sequence repeat (SSR) markers in order to evaluate their level of genetic biodiversity. The results reveal, for the first time, the high genetic biodiversity of horticultural ecotypes of the Campania Region. This feature is very important to improve the quality and productivity of agroecosystems.

Study of polymorphism of maize using dna and protein markers

In the present investigation 40 genotypes of maize from Czechoslovakia, Hungary, Poland, Union of Soviet Socialist Republics, Slovakia and Yugoslavia were analysed using 20 start codon targeted (SCoT) markers, 10 simple sequence repeat (SSR) markers, 13 random amplified polymorphic (RAPD) markers and using SDS-PAGE markers. Twenty SCoT primers produced 114 DNA fragments with an average of 5.7 bands per primer. Out of the total of 114 amplified fragments, 86 (76.43 %) were polymorphic, with an average of 4.30 polymorphic bands per primer. Ten SSR primers revealed a total of 65 alleles ranging from 4 (UMC1060) to 8 (UMC2002 and UMC1155) alleles per locus with a mean value of 6.50 alleles per locus. 20 SCoT primers produced total 114 fragments across 40 maize genotypes, of which 86 (76.43 %) were polymorphic with an average of 4.30 polymorphic fragments per primer and number of amplified fragments ranged from 2 (SCoT 45) to 8 (SCoT 28 and SCoT 63). The number of total scorable protein bands was twentythree as a result of SDS-PAGE technique but those that were not cosistent in reproducibility and showed occasional variation in sharpness and density were not considered. Based on these bands forty accessions of maize were screened. Out of twentythree polypeptide bands, 6 (31%) were commonly present in all accessions and considered as monomorphic, while 17 (65%) showed variations and considered as polymorphic. The dendrogram of 40 old maize genotypes based on SSR, SCoT, RAPD and SDS-PAGE markers using UGMA algorithm was constructed.

Characterization of Antibiosis to Diabrotica speciosa (Coleoptera: Chrysomelidae) in Brazilian Maize Landraces

Resistance to insect pests can be found in several native, landrace plants and can be an important alternative to conventional control methods. Diabrotica speciosa (Germar) (Coleoptera: Chrysomelidae) larvae are important maize (Zea mays L.) (Cyperales: Poaceae) root pests and finding native resistance in landraces would greatly contribute to maize-breeding programs aimed at controlling this pest. This study investigated whether the growth, survival, oviposition rhythm, fecundity, and fertility of D. speciosa are negatively influenced by specific maize landraces, and the existence of any morphological barriers in the roots that may correlate with plant resistance to the larval attack. Nineteen genotypes (17 landraces and 2 cultivars) were screened for antibiosis in assays that were conducted in the laboratory using seedling maize plants where the development time, longevity, weight, total survival, and sex ratio of adults were evaluated. Out of nineteen genotypes, eight were selected according to their resistance levels for an additional rearing study evaluating oviposition and fecundity. Landrace Pérola and cultivar SCS 154-Fortuna were classified as resistant because they increased the maturation period from larva to adult and decreased survivorship; and the landrace Palha Roxa was also classified as resistant for showing a lower fertility rate than other landraces. Resistant landraces that were infested by D. speciosa larvae showed greater amounts of some morphological barriers comparing with uninfested plants. The landraces classified as resistant may be considered in future plant-breeding programs, aiming to develop resistant maize cultivars to D. speciosa larval attack.

Genetic variation of european maize genotypes (Zea mays L.) Detected using ssr markers

The SSR molecular markers were used to assess genetic diversity in 40 old European maize genotypes. Ten SSR primers revealed a total of 65 alleles ranging from 4 (UMC1060) to 8 (UMC2002 and UMC1155) alleles per locus with a mean value of 6.50 alleles per locus. The PIC values ranged from 0.713 (UMC1060) to 0.842 (UMC2002) with an average value of 0.810 and the DI value ranged from 0.734 (UMC1060) to 0.848 (UMC2002) with an average value of 0.819. 100% of used SSR markers had PIC and DI values higher than 0.7 that means high polymorphism of chosen markers used for analysis. Probability of identity (PI) was low ranged from 0.004 (UMC1072) to 0.022 (UMC1060) with an average of 0.008. A dendrogram was constructed from a genetic distance matrix based on profiles of the 10 maize SSR loci using the unweighted pair-group method with the arithmetic average (UPGMA). According to analysis, the collection of 40 diverse accessions of maize was clustered into four clusters. The first cluster contained nine genotypes of maize, while the second cluster contained the four genotypes of maize. The third cluster contained 5 maize genotypes. Cluster 4 contained five genotypes from Hungary (22.73%), two genotypes from Poland (9.10%), seven genotypes of maize from Union of Soviet Socialist Republics (31.81%), six genotypes from Czechoslovakia (27.27%), one genotype from Slovak Republic (4.55%) and one genotype of maize is from Yugoslavia (4.55%). We could not distinguish 4 maize genotypes grouped in cluster 4, (Voroneskaja and Kocovska Skora) and 2 Hungarian maize genotypes - Feheres Sarga Filleres and Mindszentpusztai Feher, which are genetically the closest.

Start codon targeted (scot) polymorphism reveals genetic diversity in european old maize (Zea mays L.) Genotypes

Maize (Zea mays L.) is one of the world's most important crop plants following wheat and rice, which provides staple food to large number of human population in the world. It is cultivated in a wider range of environments than wheat and rice because of its greater adaptability. Molecular characterization is frequently used by maize breeders as an alternative method for selecting more promising genotypes and reducing the cost and time needed to develop hybrid combinations. In the present investigation 40 genotypes of maize from Czechoslovakia, Hungary, Poland, Union of Soviet Socialist Republics, Slovakia and Yugoslavia were analysed using 20 Start codon targeted (SCoT) markers. These primers produced total 114 fragments across 40 maize genotypes, of which 86 (76.43%) were polymorphic with an average of 4.30 polymorphic fragments per primer and number of amplified fragments ranged from 2 (SCoT 45) to 8 (SCoT 28 and SCoT 63). The polymorphic information content (PIC) value ranged from 0.374 (ScoT 45) to 0.846 (SCoT 28) with an average of 0.739. The dendrogram based on hierarchical cluster analysis using UPGMA algorithm was prepared. The hierarchical cluster analysis showed that the maize genotypes were divided into two main clusters. Unique maize genotype (cluster 1), Zuta Brzica, originating from Yugoslavia separated from others. Cluster 2 was divided into two main clusters (2a and 2b). Subcluster 2a contained one Yugoslavian genotype Juhoslavanska and subcluster 2b was divided in two subclusters 2ba and 2bb. The present study shows effectiveness of employing SCoT markers in analysis of maize, and would be useful for further studies in population genetics, conservation genetics and genotypes improvement.