Heredity of tomato mosaic virus (ToMV) and potato virus Y (PVY) resistance in eggplant (Solanum melongena L.)

Heredity of tomato mosaic virus (ToMV) and potato virus Y (PVY) resistance in eggplant (Solanum melongena L.)

Wageningen Plant Research International Netherlands

2004

p.154-160

SB348.P46E8 2004

The purpose of this research was to determine the genetic control of resistance against ToMV (Tomato mosaic virus, genus Tobamovirus) and PVY (Potato virus Y, genus Potyvirus) of a set of gcnitors recently identified at INRA, and to search for molecular markers linked to the resistance factors.The availability of a complete molecular map of eggplant makes now possible comparisons between Solanaceous crops. To determine whether synteny occurs between eggplant, tomato, tobacco and pepper for resistance genes controlling the same viruses, RFLP markers linked to the locus Tml, Tm2 (tomato), N (tobacco), L (pepper) controlling resistance against Tobamoviruscs, and pvr2 and Pvr4 (pepper), pot I (tomato), Ry (potato) controlling resistance against Potyviruses were tested in eggplant. F I, F2 and BC 1 progenies from the cross between an accession of S. melongena (MM 136) resistant against ToMV pathotype 0 and a susceptible one (MM 608) have been inoculated two weeks after sowing, by manual cotyledons abrasion. The results show that a dominant gene, named Tbm-I (for "tobaamovirus I "), is responsible for the resistance. This gene controls a hypersensitive reaction on the inoculated organs and an absence of symptoms on the systemic leaves. Morover, heterozygous plants for Tbm-I manually inoculated at the cotyledon stage present generalized systemic necrosis, similarly to the Tm2 gene from tomato. Because of the low level of RFLP polymorphism between the two S. melongena accessions, it was not possible to determine whether RFLP markers linked to phenotypically similar resistance gene in other solanaceous crops are linked or not to Tbm-I. A higher level of polymorphism was obtained using AFLP markers; these markers arc currently used to localize Tbm-I on the eggplant genome. For studying the heredity of PVY resistance, F I, F2 and BC I interspecific progenies from the cross S. linnaeanum MM 195 (susceptible) and S. melongena MM 738 (resistant) have been used. Plants were inoculated twice, three and then four weeks after sowing. One month after the second inoculation, presence/absence ofPVY systemic infection was assessed by ELISA. The results obtained indicate that a single recessive gene, named ptv-I (for "J2o1Y irus" I) is involved in the resistance. Phenotypically, ptv-l shares strong similarities withpvr2 from pepper and pot-I from tomato. Some of the RFLP markers linked to pvr2 and pot-I presented polymorphism between MM 195 and MM 738 and are currently under mapping to determine whetherptv-I is an ortholog ofpvr2 and pot-I.

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