Amplifluor-Based SNP Genotyping.

Amplifluor, a genotyping system used to analyze single nucleotide polymorphisms (SNPs), is supplied by Merck-Millipore. Amplifluor is based on polymerase chain reaction (PCR) with two competing allele-specific primers and a SNP specific common reverse primer. Sequence information flanking SNP of interest and fluorescent plate reader for end-point measurement or qPCR machine for real time measurement are required for the execution of the Amplifluor assay. In this chapter, the principle and working protocol of the Amplifluor assay based on end-point fluorescence detection of SNP allele is presented with an example.

Genomic regions associated with resistance to Fusarium wilt in castor identified through linkage and association mapping approaches.

Fusarium wilt, caused by Fusarium oxysporum f. sp. ricini, is the most destructive disease in castor. Host plant resistance is the best strategy for the management of wilt. Identification of molecular markers linked to wilt resistance will enhance the efficiency and effectiveness of breeding for wilt resistance. In the present study, genomic regions linked to wilt resistance were mapped using a bi-parental population of 185 F6-RILs and a genetically diverse panel of 300 germplasm accessions. Quantitative trait loci (QTL) analysis performed using a linkage map consisting of 1090 SNP markers identified a major QTL on chromosome 7 with an LOD score of 18.7, which explained 44% of the phenotypic variance. The association mapping performed using genotypic data from 3465 SNP loci revealed 69 significant associations (p < 1 × 10-4) for wilt resistance. The phenotypic variance explained by the individual SNPs ranged from 0.063 to 0.210. The QTL detected in the bi-parental mapping population was not identified in the association analysis. Thus, the results of this study indicate the possibility of vast gene diversity for Fusarium wilt resistance in castor.

Development and genetic analysis of conspicuous purple coloured corolla lip flower with multicapsules genotype in sesame (Sesamum indicum L.).

The present investigation was framed to understand the genetics and development of conspicuous purple coloured corolla tip flower and multicapsules at axil in sesame (Sesamum indicum L.) from the cross between genotypes IC-205776 (♀) 9 EC-118591 (♂). The conspicuous corolla lip colour is recessive in expression and under digenic control, differing from the earlier reports. The ratio at F2 generation was best fit for 13:3 indicating inhibitory gene action for purple corolla lip colour. Among two genes, one acts as an inhibitory gene at recessive condition to produce conspicuous purple corolla lip colour. Multicapsules/axil is dominant in expression, controlled by more than one gene. The ratio of multiple capsules/axil and single capsules/axil at F2 generation was the best fit for the ratio 11:5 indicating dominance modification of duplicate genes for a number of capsules per axil. Single capsule/axil results due to dominance modification of duplicate genes where the homozygous condition of one gene reverses the dominance relation of another gene in heterozygous condition. Joint segregation analysis indicated independent segregation of corolla lip colour and capsule number per axil.