Introgression Lines with Improved Resistance to Late Leaf Spot and Rust in Peanut

In an effort to simultaneously transfer and map the genomic regions governing resistance to late leaf spot (LLS) and rust in peanut, two susceptible varieties (lCGS 76 and OH 86) were crossed to two resistant synthetic tetraploids; an amphidiploid, ISATGR 278- 18 (Arachis duranensis x Arachis batizocoi) and an autotetraploid, ISATGR 5B (Arachis magna x Arachis batizocoi). Two cycles of backcrossing with the recurrent parents resulted in the development of a large number of introgression lines (ILs). They (BCl6 and BCl,) were evaluated during the rainy season of 2013 and 2014. ILs differed significantly for LLS and rust resistance, and productivity traits. Twenty seven introgression lines superior over lCGS 76, and three ILs superior over OH 86 for pod yield were selected from respective crosses. Many of them were highly resistant to both LLS and rust. Majority of them carried resistant allele at marker loci linked to LLS and rust. A few ILs also combined high test weight, shelling percentage and sound mature kernel percentage. Of these introgression lines, eleven were also superior over GPBO 4, a national check variety. These genetic resources can be of immense use in peanut breeding or for commercialization

Characterization of AhMITE1 transposition and its association with the mutational and evolutionary origin of botanical types in peanut (Arachis spp.)

AhMITE1 is an active miniature inverted repeat transposable element (MITE) in peanut (Arachis hypogaea L). Its transpositional activity from a particular (FST1-linked) site within the peanut genome was checked using AhMITE1-specifc PCR, which used a forward primer annealing to the 5′-flanking sequence and a reverse primer binding to AhMITE1. It was found that transposition activation was induced by stresses such as ethyl methane sulfonate (EMS), gamma irradiation, environmental conditions, and tissue culture. Excision and insertion of AhMITE1 at this particular site among the mutants led to gross morphological changes resembling alternate subspecies or botanical types. Analysis of South American landraces revealed the presence of AhMITE1 at the site among most of the spp. fastigiata types, whereas the element was predominantly missing from spp. hypogaea types, indicating its strong association. Four accessions of the primitive allotetraploid, A. monticola were devoid of AhMITE1 at the site, indicating only recent activation of the element, possibly because of the “genomic shock” resulting from hybridization followed by allopolyploidization