Identification of loci affecting flavour volatile emissions in tomato fruits

Abstract

Fresh tomato fruit flavour is the sum of the interaction between sugars, acids, and a set of approximately 30 volatile compounds synthesized from a diverse set of precursors, including amino acids, lipids, and carotenoids. Some of these volatiles impart desirable qualities while others are negatively perceived. As a first step to identify the genes responsible for the synthesis of flavour-related chemicals, an attempt was made to identify loci that influence the chemical composition of ripe fruits. A genetically diverse but well-defined Solanum pennellii IL population was used. Because S. pennellii is a small green-fruited species, this population exhibits great biochemical diversity and is a rich source of genes affecting both fruit development and chemical composition. This population was used to identify multiple loci affecting the composition of chemicals related to flavour. Twenty-five loci were identified that are significantly altered in one or more of 23 different volatiles and four were altered in citric acid content. It was further shown that emissions of carotenoid-derived volatiles were directly correlated with the fruit carotenoid content. Linked molecular markers should be useful for breeding programmes aimed at improving fruit flavour. In the longer term, the genes responsible for controlling the levels of these chemicals will be important tools for understanding the complex interactions that ultimately integrate to provide the unique flavour of a tomato.

Tomato aromatic amino acid decarboxylases participate in synthesis of the flavor volatiles 2-phenylethanol and 2-phenylacetaldehyde

“…This line contains a locus, malodorous, that is associated with a large increase in emissions of 2-phenylacetaldehyde and 2-phenylethanol. We have routinely observed Ͼ1,000-fold increases in these two volatiles over multiple growing seasons (14). Because of this robust behavior, we used IL8-2-1 and its near isogenic parent M82 for subsequent analyses.…”

“…E. coli containing the control ␤-glucuronidase gene had no detectable activity. Decarboxylase activity was determined by the method of Facchini et al (25) with [U-14 C]phenylalanine or [U- 14 C]tyrosine as a substrate and measuring the release of 14 CO 2 . It was first determined that the reaction was linear for 4 h at 30°C; subsequent assays were run for 3 h. To determine the stoichiometry of the reaction, [ 14 C]phenethylamine was separated from the reaction mix with the two-column system described above.…”

A Visual Reporter System for Virus-Induced Gene Silencing in Tomato Fruit Based on Anthocyanin Accumulation

“…We think that the observed differences may be due to the different genetic backgrounds of the tomato lines and their respective developmental rates. There is evidence that b-carotene pools are synthesized in the fruit before ripening, at least in certain genetic backgrounds (Tieman et al, 2006). Fruit VIGS experiments, which are initiated at the mature-green stage, may or may not block preripening synthesis of b-carotene depending on the speed at which silencing signals spread through the fruit with respect to the precise developmental stage in which biosynthesis takes place, which may be heavily influenced by the genetic background.…”

Identification and mapping of quantitative resistance to late blight (Phytophthora infestans) in Solanum habrochaites LA1777

“…At least five IL populations have been developed in tomato; they are derived from S. pennellii LA716 (Eshed and Zamir 1994), S. habrochaites LA1777 (Monforte and Tanksley 2000), S. habrochaites LA407 (Francis et al 2001), S. habrochaites LYC4 (Finkers et al 2007) and S. lycopersicoides LA2951 (Canady et al 2005). The S. pennellii IL library has been extensively explored to identify QTLs for several traits including disease resistances (Astua-Monge et al 2000;Smart et al 2007), fruit quality (Rousseaux et al 2005;Tieman et al 2006) and yield . Recently, an introgression line of S. habrochaites LA1777 has been identified with a significant contribution to marketable fruit yield (Hanson et al 2007).…”