Development and characterization of a new set of genomic microsatellite markers in rice bean (Vigna umbellata (Thunb.) Ohwi and Ohashi) and their utilization in genetic diversity analysis of collections from North East India.

Rice bean [Vigna umbellate (Thumb.) Ohwi and Ohashi] is an underutilized crop believed to be domesticated in the Myanmar-Thailand region of Asia. In India, rice bean is mainly cultivated in the North-Eastern Hills, which is a hotspot for biological diversity. A 5' anchored PCR was used to develop microsatellite markers in rice bean. Twenty-eight specific primer pairs were designed and employed to characterize sixty five ricebean accessions collected from North East India. A total of 179 alleles were amplified with an average of 6.393 alleles per locus. The gene diversity was high (mean 0.534) in the accessions collected from Darjeeling, Nagaland and Manipur, which are bordering areas with East Nepal and Myanmar, respectively. Exceptionally high outcrossing rate was observed in the entire population. Population structure analysis identified three distinct clusters in which accessions collected from areas bordering Myanmar and East Nepal grouped separately. Using a combination of STRUCTURE and Principal Coordinate Analysis, relative affinity of the intermediate accessions could be established. However, differences in allelic counts among populations were non-significant. The results showed that there is a high level of genetic diversity within the accessions, with high outcrossing rate.

A case study on the genetic origin of the high oleic acid trait through FAD2-1 DNA sequence variation in safflower (Carthamus tinctorius L.).

The safflower (Carthamus tinctorius L.) is considered a strongly domesticated species with a long history of cultivation. The hybridization of safflower with its wild relatives has played an important role in the evolution of cultivars and is of particular interest with regards to their production of high quality edible oils. Original safflower varieties were all rich in linoleic acid, while varieties rich in oleic acid have risen to prominence in recent decades. The high oleic acid trait is controlled by a partially recessive allele ol at a single locus OL. The ol allele was found to be a defective microsomal oleate desaturase FAD2-1. Here we present DNA sequence data and Southern blot analysis suggesting that there has been an ancient hybridization and introgression of the FAD2-1 gene into C. tinctorius from its wild relative C. palaestinus. It is from this gene that FAD2-1Δ was derived more recently. Identification and characterization of the genetic origin and diversity of FAD2-1 could aid safflower breeders in reducing population size and generations required for the development of new high oleic acid varieties by using perfect molecular marker-assisted selection.