TheMi-9Gene fromSolanum arcanumConferring Heat-Stable Resistance to Root-Knot Nematodes Is a Homolog ofMi-1 

Abstract

Resistance conferred by the Mi-1 gene from Solanum peruvianum is effective and widely used for limiting root-knot nematode (Meloidogyne spp.) yield loss in tomato (Solanum lycopersicum), but the resistance is ineffective at soil temperatures above 28°C. Previously, we mapped the heat-stable resistance gene Mi-9 in Solanum arcanum accession LA2157 to the short arm of chromosome 6, in a genetic interval as Mi-1 and the Cladosporium fulvum resistance gene Cf2. We developed a fine map of the Mi-9 region by resistance and marker screening of an F 2 population and derived F 3 families from resistant LA2157 3 susceptible LA392. Mi-1 intron 1 flanking primers were designed to amplify intron 1 and fingerprint Mi-1 homologs. Using these primers, we identified seven Mi-1 homologs in the mapping parents. Cf-2 and Mi-1 homologs were mapped on chromosome 6 using a subset of the F 2 . Cf-2 homologs did not segregate with Mi-9 resistance, but three Mi-1 homologs (RH1, RH2, and RH4) from LA2157 and one (SH1) from LA392 colocalized to the Mi-9 region. Reverse transcriptase-polymerase chain reaction analysis indicated that six Mi-1 homologs are expressed in LA2157 roots. We targeted transcripts of Mi-1 homologs for degradation with tobacco (Nicotiana tabacum) rattle virus (TRV)-based virus-induced gene silencing using Agrobacterium infiltration with a TRV-Mi construct. In most LA2157 plants infiltrated with the TRV-Mi construct, Mi-9-meditated heat-stable root-knot nematode resistance was compromised at 32°C, indicating that the heat-stable resistance is mediated by a homolog of Mi-1.

Virus-induced gene silencing and its application in plant functional genomics

“…Some genes have been found to have important roles in resistance against nematodes and aphids, such as SlWRKY72a, HSP90, LeMPK2, LeMPK1, LeMPK3, SlSERK1, and SGT1 [116][117][118][119][120]. Suppressing threonine deaminase (TD) and germin-like, jasmonateresistant4 (JAR4) by VIGS confirmed that these genes have important roles in activating plant defenses to M. sexta [121,122].…”

Abscisic Acid Deficiency Antagonizes High-Temperature Inhibition of Disease Resistance through Enhancing Nuclear Accumulation of Resistance Proteins SNC1 and RPS4 in Arabidopsis

“…A moderate increase in temperature inhibits defense responses mediated by a number of R genes, including N, Mi, RPS4, and SNC1 (Dropkin, 1969;Malamy et al, 1992;Jablonska et al, 2007;, whereas a chilling temperature is required for some gain-offunction mutants in R or R-related genes to induce defense responses (Huang et al, 2010;Yang et al, 2010). Recently, it has been shown that R genes could be the temperature-sensitive component in defense responses, and alteration of R protein activity can change temperature sensitivity of the defense responses (Zhu et al, 2010).…”

Phylogenomics of 42 tomato chloroplasts using assembly and alignment-free method

“…It could be expected that certain philogenetic relationships may change as more taxons are further added in future studies using this method. Finally, it is interesting to observe that S. peruvianum TS-403 lies within the Eriopersicon informal group, whilst S. peruvianum TS-402 lies within the Arcanum informal group, which can be readily accounted for when considering that the first corresponds to S. peruvianum (north) variety whilst the second corresponds to S. peruvianum (south) variety 26 .…”

“…Peralta and Spooner 8 included S. peruvianum North within Arcanum group and S. peruvianum South within the Eriopersicon group. This comes as no surprise given the fact that that TS-404 and TS-403 correspond to the S. peruvianum South variety, whilst TS-402 corresponds to the S. peruvianum North variety 26 . In the filtered supernetwork, the three principal Lycopersicon subgroups are clearly separated, with the S. pimpinellifolium distributed among the three, and all four of them closely connected to the nodes separating these three subgroups, which consequently indicates a close relationship between them.…”