Variation for Resistance to Aphids (Homoptera: Aphididae) Among Tomato Inbred Backcross Lines Derived from Wild <I>Lycopersicon</I> Species

Abstract

Two tomato inbred backcross line (IBL) populations, derived from crosses between aphid-susceptible Lycopersicon esculentum Mill. 'Peto 95-43' X resistant wild L. pennellii Corr (D'arcy) accession LA716, and Peto 95-43 X resistant wild L. hirsutum f. glabratum Mull accession LA407, were evaluated in replicated field experiments for resistance to potato aphid, Macrosiphum euphorbiae (Thomas), and green peach aphid, Myzus persicae (Sulzer). Aphid infestation scores for each IBL and control (LA716, LA407, Peto 95-43, and susceptible 'Alta') plot were recorded weekly for 5 and 9 wk during the summers of 2000 and 2001, respectively. Aphid infestation scores from leaflets were used to calculate area under the infestation pressure curve (AUIPC), a measure of aphid infestation throughout the growing season, for each IBL and control. Score AUIPC was highly correlated with actual aphid count AUIPC, indicating that scores accurately reflected aphid infestation. Score AUIPC was also highly correlated across both years (2000 and 2001) and locations. Low score AUIPC was significantly correlated with larger plant size and sprawling, indeterminate plant growth habit. Seven IBLs, LA716, and LA407 were significantly more resistant to aphids (lower score AUIPC) than susceptible parent Peto 95-43 in both years. Two IBLs, 1034 and 1051, were not significantly different from resistant LA407 for score AUIPC in both years. The seven aphid-resistant IBLs identified here can be useful as donor parent material for resistance breeding efforts in cultivated tomato.

Genome Mapping and Molecular Breeding of Tomato

“…A later study revealed that several isolates of potato aphid and green peach aphid ( Myzus persicae ) can overcome the resistance mediated by Mi ( Meu1 ), limiting the use of this gene for aphid control in tomato [391]. In a more recent study, two tomato BI populations, derived from crosses between two different aphid susceptible L. esculentum lines and two aphid resistant accessions of L. pennellii and L. hirsutum , were evaluated for resistance to both potato aphid and green peach aphid [80]. Field screening over two years resulted in the identification of seven BILs (BC 2 S 3 to BC 2 S 6 ) with resistance to both types of aphid.…”

“…Unfortunatley, most of these resources have not been characterized or utilized for insect resistance breeding, though a few inheritance studies have been undertaken [70, 77, 78]. Breeding for insect resistance in tomato has generally encountered more difficulties than breeding for disease resistance, linkage drag being a major impediment [34, 72, 79, 80]. It is expected that identification of markers associated with insect resistance and use of MAS will help alleviate some of the difficulties in developing insect resitant cultivars.…”

Effect of cucumber mosaic virus infection on morphology, yield and phenolic contents of tomato

“…Average M. persicae population on three leaves from the upper, middle and lower parts of 10 plants per genotype was calculated (Akhtar et al 2010). Genotypes were ranked as highly resistant, resistant and susceptible on the basis of aphid infestation scores following the trinomial sampling scale: 0 ¼ no aphids; 1 ¼ 1-10 aphids and 2 ¼ 11 or more aphids (Kohler and Clair 2005;Akhtar et al 2010). …”

Resistance of Solanum species to Cucumber mosaic virus subgroup IA and its vector Myzus persicae

“…The populations of M. persicae on three leaves, upper, middle and lower parts of 10 plants per genotypes, were recorded. Genotypes were ranked as highly resistant, resistant and susceptible on the basis of aphid infestation scores following the trinomial sampling scale; 0 = no aphids (highly resistant); 1 = 1-10 aphids per leaf (resistant) and 2 = 11 or more aphids per leaf (susceptible) (Kohler and St. Clair 2005).…”