Genetic Diversity in the Semi-Arid Grown Cowpea(<i>Vigna unguiculata</i>L. Walp)Accessions Using Morphological and Molecular Characterization

Assessment of genetic diversity of the indigenous crop accessions is extremely important for breeders to identify potential parents in cross-breeding programs. Fourteen cowpea accessions collected from different parts of Sudan were used for characterization at morphological and molecular levels. The seeds of the accessions were sown in the field using a randomized complete block design with three replicates. Sixteen morphological descriptors (9 qualitative and 7 quantitative) and 20 Random Amplified Polymorphic DNA (RAPD) markers were used for characterization of the accessions. The results of morphological data revealed considerable variability within and between state’s accessions. Some morphological traits revealed similarity between accessions from different states. Among the 20 RAPD markers used, 18 were polymorphic. A total of 379 polymorphic patterns were generated;polymorphic information content (PIC) ranged from 0.63 to 0.98 with an average of 0.9. The number of fragment detected ranged from 2 for OPL-11 to 51 for OPY-2 with an average of 26.06/primer and 27.07/genotype. One to five (1 - 5) unique fragments of different sizes were detected for particular accessions, which may provide a valuable resource for breeding superior cowpea cultivars in Sudan and other semi-arid zones. Genetic similarity was ranged from 0.02 to 0.47 with an average of 0.25. Highest genetic similarity was between genotypes HSD-2966 and HSD-2967 and between genotypes HSD-5131 and HSD-5627 and the lowest was between HSD-5131 and HSD-5861 followed by that between HSD-2976 and HSD-29130 accessions. The study recommends the combination of morphological and molecular data for more efficient genetic diversity assessment and management.

Morphological and Genetical Variability among Rhizoctonia solani Isolates Causing Sheath Blight Disease of Rice

Eighteen isolates of Rhizoctonia solani collected from infected rice plants in four different locations of Bangladesh were studied by using morphological characters and molecular markers. Anastomosis study with a reference isolate confirmed that all the isolates belonged to R. solani. Significant variation was observed in sclerotial size, shape and distribution. Un-weighted pair group method with arithmetic mean dendrogram constructed based on the Gower＇s general similarity coefficient showed that these isolates were grouped into four clusters at the 0.68 similarity coefficent according to morphological characters. Cluster I was a major cluster consisting of 13 isolates, while clusters Ⅱ to Ⅳ consisted of 1 or 2 isolates. Analyses by variable number of tandem repeat and amplified fragment length polymorphism markers showed that the isolates were grouped into five and three clusters at a similarity coefficient of 0.64 and 0.69, respectively. Although most of the variability was found between isolates from different regions as expected, significant variation was observed within the isolates collected from similar agro-ecological regions. Our results suggest the presence of different races of R. solani within the same local geographic regions.

Research Progress on Genetic Diversity of Cultivated Soybean Germplasm Resources in China

In this paper,by analyzing the genetic diversity of cultivated soybean germplasm resources in China,the environmental and genotypic factors that affect the genetic diversity of cultivated soybean germplasm resources were explored to further expand the genetic basis of the existing germplasm resources of cultivated soybean in China. Moreover,research progress on genetic diversity of cultivated soybean in China was summarized,which not only revealed the geographical characteristics of genetic diversity of cultivated soybean in China,but also proposed direction for research of genetic diversity of soybean.

Molecular Tagging and Mapping of Quantitative Trait Loci for Lint Percentage and Morphological Marker Genes in Upland Cotton

Using 219 F2 Individuals developed by crossing the genetic standard line TM-1 and the multiple dominant marker line T586 In Gossyplum hirsutum L., a genetic linkage map with 19 linkage groups was constructed based on simple sequence repeat （SSR） markers. Compared with our tetraploid backboned molecular genetic map from a （TM-1xHal 7124）xTM-1 BC1 population, 17 of the 19 I｜nkage groups were combined and anchored to 12 chromosomes （sub-genomes）. Of these groups, four morphological marker genes In T586 had been mapped Into the molecular linkage map. Meanwhile, three quantitative trait loci for lint percentage were tagged and mapped separately on the A03 linkage group and chromosome 6.