Chinnappareddy L.R.D., Khandagale K., Chennareddy A., Ramappa V.G. (2013) The genus Allium (Family: Alliaceae) is the most important among the bulbous vegetable crops. Characterization of Alliums based on phenotypic traits is influenced by the environment and leads to biased diversity estimates. Recognizing the potential of DNA markers in plant breeding, researchers have adopted the molecular markers for marker-assisted selection (MAS), quantitative trait loci (QTL) mapping and characterization of different quality traits in Alliums. This review presents details about the use of DNA markers in Alliums for cultivar identification, diversity studies, SSR development, colour improvement, total soluble solids (TSS), cytoplasmic male sterility (CMS) and efforts of DNA sequencing. As there are no such reports to describe the above work under a single heading, we decided to mine literature for those who are working in onion, garlic, chives and leek improvement to generate new insights in the subject.
Eggplant (Solanum melongena L.) is an important crop in terms of economic and genetic significance in tropical and subtropical regions. The Indian Institute of Horticulture Research (IIHR) eggplant breeding program produced five genotypes with increased yield and excellent producer acceptance. Molecular profiles of these genotypes were developed using 39 EST-SSR primers for maximum discrimination and repeatability at 35 loci. In total there were 181 alleles with the number of alleles per locus ranging from 9.0 (EEMS 24) to 3 (EEMS 46 and EEMS 20), with a mean of 5.02 alleles per locus ranging from 85 to 300 bp. Polymorphic information content of the markers ranged from 0.343 to 0.794. Expected heterozygosity ranged from 0.560 to 0.880 and the probability of identity ranged from 0.010 to 0.376. Pair-wise comparison of microsatellite data led to development of an unweighted pair group method with arithmetic mean dendrogram and DNA barcodes for easy and accurate identification of eggplant genotypes with combinations of their morphological traits. The results indicate that 'IIHR-3' and 'IIHR-7' originated from a single source and 'Arka Anand' is a cross between 'IIHR-3' and 'SM-6-6', indicating a good fit with genetic similarity values. The DNA barcode fingerprint can be deposited and used for clear identification of eggplant genotypes and to address intellectual property rights-related issues.
Nearly 5 000 aphid species damage crops, either by sucking plant sap or as disease-transmitting vectors. Microsatellites are used for understanding molecular diversity and eco-geographical relationships among aphid species. Expressed sequence tag (EST)-microsatellite motifs were identified through an in silico approach using inbuilt simple sequence repeat mining tools in aphid EST dataset. Microsatellite mining revealed one in every five aphid genes as containing a repeat motif, and out of 9 290 EST microsatellites mined from Aphis gossypii Glover and Acyrthosiphon pisum (Harris) (both Hemiptera: Aphididae), 80% were of A and/or T (AT, ATA, AAT, AATA, and ATTT) motifs, and the rest contained G and/or C motifs. All microsatellite sequences were annotated using BLAST. Primers for EST microsatellites were designed using the Primer 3.0 tool. 106 primer pairs of both dinucleotide repeats (DNRs) and trinucleotide repeats (TNRs), representing open reading frames (ORFs) and untranslated regions (UTRs), were synthesized to amplify 15 aphid species belonging to the subfamily Aphidinae, collected from diverse hosts. Four hundred forty-five polymorphic alleles were amplified. Fifty TNR and 23 DNR microsatellites amplified across the species studied. Polymorphism information content values of microsatellites ranged from 0.23 to 0.91, amplifying 2-16 alleles. Genetic similarity indices were estimated using the 'NTSYS-pc' software package. Unweighted pair group with arithmetic mean and principal component analysis resolved taxonomic relationships of the aphid species studied. The new aphid microsatellites developed will provide valuable information to researchers to study Indian aphid species diversity and genetic relationships.
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