Quantitative trait loci regulating the fatty acid profile of acylsugars in tomato

Abstract

Acylsugars are secondary metabolites with proven insect resistance properties that are produced by many Solanaceous species including Solanum pennellii, a wild relative of tomato. The acylsugar chemotypes of S. pennellii varies greatly within its natural range and might be the product of plant/insect coevolution. The S. pennellii accession LA716 was used to transfer increased levels of acylsugar production into the cultivated tomato, resulting in the acylsugar tomato breeding line CU071026. S. pennellii accession LA716 produces high levels of acylsugars with chemotypes that differ greatly from those produced by CU071026 or the trace acylsugars of cultivated tomato. Understanding the genetic regulation of acylsugar chemistry will aid efforts to breed acylsugar production into cultivated tomato, allowing for alteration of both acylsugar base moieties and fatty acid profiles. This study uses a BC1F1 population produced from the cross of S. pennellii LA716 and CU071026 with CU071026 as the recurrent parent to identify QTL that change the fatty acid profile of acylsugars. Multiple QTL and epistatic interactions between QTL were detected including three QTL on chromosomes 2, 5, and 7, which significantly alter the percentage of extended iso-odd branched fatty acids and straight chain fatty acids on the acylsugars. We also report the introgression of one of these QTL, FA 2, into CU071026, resulting in a new tomato line with significantly increased i11:0 as a percentage of the fatty acids in its acylsugars. Candidate genes for these QTL and the impacts of altering acylsugar fatty acid are discussed

A feedback insensitive isopropylmalate synthase affects acylsugar composition in cultivated and wild tomato

“…They also found high iC5 acylsugars for the LA1376, LA2560, and LA1809, which we identified as having iC5-dominant acylsugar acyl chains associated with the presence of at least one SlIPMS3-like long-form allele in the genome. The influence of this region of S. pennellii chromosome 8 on S. lycopersicum iC4 versus iC5 composition is also consistent with published quantitative trait locus mapping and breeding studies from Martha Mutschler and colleagues (Blauth et al, 1999;Leckie et al, 2014). …”

“…Their activity in plant protection led to interest in breeding for altered acylsugar quantities and composition in Solanum lycopersicum (cultivated tomato). Because acylsugars are especially abundant and structurally varied in wild tomato species Schilmiller et al, 2010Schilmiller et al, , 2015Kim et al, 2012;Ghosh et al, 2014), these relatives provide an attractive source of variation for improvement in S. lycopersicum pest tolerance (Maluf et al, 2010;Leckie et al, 2012Leckie et al, , 2014.…”

In vitro reconstruction and analysis of evolutionary variation of the tomato acylsucrose metabolic network

“…Nicotiana attenuata acylsucroses are at the center of a multitrophic defense interaction where they are metabolized to volatile fatty acids by Manduca sexta larvae, and these airborne products attract predatory ants (6). Protective properties against herbivores have made increasing total acylsugars or altering acyl chain types a target for breeding insect-resistant cultivated tomatoes (Solanum lycopersicum) (16)(17)(18). In addition, synthetic sucrose esters mimicking natural acylsugars have been applied as safe, biodegradable insecticidal compounds (19)(20)(21) and also have commercial value in the food, cosmetic, and pharmaceutical industries (22,23).…”

Tomato Breeding for Insect-Pest Resistance

“…Tomato breeding programs aimed at obtaining pest-resistant cultivars have adopted the strategy of incorporating genes responsible for the production of glandular allelochemicals and/or trichomes [58][59][60][61][62][63][64][65][66][67]. This strategy has succeeded because the selection for high allelochemical content and, in some cases, glandular trichomes, has led to correlated responses regarding increased resistance to key tomato pests.…”

“…Breeding programs have commonly performed the hybridization method between pest-resistant wild-type accessions and commercial crops of suitable agronomic value and highly productive traits, followed by backcrossing to the commercial S. lycopersicum cultivar (Figure 5). This technique is promising with regard to obtaining lines displaying higher pest insect and arachnid resistance levels [38,39,[58][59][60][64][65][66].…”