Fine mapping of the nematode resistance gene Mi-3 in Solanum peruvianum and construction of a S. lycopersicum DNA contig spanning the locus

Abstract

Currently, the only genetic resistance against root-knot nematodes in the cultivated tomato Solanum lycopersicum (Lycopersicon esculentum) is due to the gene Mi-1. Another resistance gene, Mi-3, identified in the related wild species Solanum peruvianum (Lycopersicon peruvianum) confers resistance to nematodes that are virulent on tomato lines that carry Mi-1, and is effective at temperatures at which Mi-1 is not effective (above 30 degrees C). Two S. peruvianum populations segregating for Mi-3 were used to develop a high-resolution map of the Mi-3 region of chromosome 12. S. lycopersicum BACs carrying flanking markers were identified and used to construct a contig spanning the Mi-3 region. Markers generated from BAC-end sequences were mapped in S. peruvianum plants in which recombination events had occurred near Mi-3. Comparison of the S. peruvianum genetic map with the physical map of S. lycopersicum indicated that marker order is conserved between S. lycopersicum and S. peruvianum. The 600 kb contig between Mi-3-flanking markers TG180 and NR18 corresponds to a genetic distance of about 7.2 cM in S. peruvianum. We have identified a marker that completely cosegregates with Mi-3, as well as flanking markers within 0.25 cM of the gene. These markers can be used to introduce Mi-3 into cultivated tomato, either by conventional breeding or cloning strategies.

Managing for soil health can suppress pests

“…UC research has been instrumental in identifying and evaluating genetic material resistant to a variety of soil pests and diseases, such as root knot nematodes (Kaloshian et al 1996;Yaghoobi et al 2005), Fusarium wilt (Scott et al 2012) and Armillaria (Baumgartner et al 2013). Recent field research evaluating experimental rootstocks for almond and stone fruit has found that some hybrids are markedly less sensitive to Prunus replant disease than others, which may result in less need for chemical controls ).…”

How Durable is Root Knot Nematode Resistance in Tomato?

“…Tomato is one of the top most crop species for which genetic markers are used in commercial breeding by last few years (Foolad 2007). Yaghoobi et al (2005) identified a tightly linked marker that is completely co-segregated with a single dominant gene Mi-3 resistant to RKN. It can be used to identify Mi-3 introgression in commercial tomato cultivars by either conventional breeding or cloning.…”

SNPs of CLAVATA receptors in tomato, in the context of root-knot nematode infection

“…S. peruvianum also showed strong resistance ( Table 1). The nematode resistance loci Mi-3 in S. peruvianum was mapped on chromosome 12 (Yaghoobi et al, 2005), but has not yet been cloned. We also found that S. pennellii showed weak resistance to root-knot nematode infection (Table 1).…”