In Vitro screening technique and polymorphic DNA markers for introgression of root knot nematode resistance in tropical carrot

The present study was aimed to develop an In Vitro procedure for screening carrot genotypes against root knot nematode (RKN), Meloidogyne spp and identify linked DNA markers. The RKN reaction of carrot genotypes was also confirmed in pot experiment and additionally, In vitro technique for screening carrot genotypes against RKN invasion by placing near 20 larvae J2s of M. incognita per root tip on pluronic gel media was effective in discriminating RKN susceptible and resistant genotypes. The technique revealed a wide variation in number of larvae that entered into roots, which was highest in black carrot Pusa Asita (12.5 larvae/root) and lowest in ‘ 6526B Sun2000’ (1.0 J2s/root). The Mj-1 resistance locus carrying European carrot lines (“6526 B Sun2000” and “8542B Vilmorin”) have potential to introgress RKN resistance in susceptible varieties of carrot. For this, STS-SQ1 marker and In vitro screening will be helpful for handling segregating materials during RKN resistance breeding.