Enzyme Activity Profiles during Fruit Development in Tomato Cultivars andSolanum pennellii     

Abstract

Enzymes interact to generate metabolic networks. The activities of more than 22 enzymes from central metabolism were profiled during the development of fruit of the modern tomato cultivar Solanum lycopersicum 'M82' and its wild relative Solanum pennellii (LA0716). In S. pennellii, the mature fruit remains green and contains lower sugar and higher organic acid levels. These genotypes are the parents of a widely used near introgression line population. Enzymes were also profiled in a second cultivar, S. lycopersicum 'Moneymaker', for which data sets for the developmental changes of metabolites and transcripts are available. Whereas most enzyme activities declined during fruit development in the modern S. lycopersicum cultivars, they remained high or even increased in S. pennellii, especially enzymes required for organic acid synthesis. The enzyme profiles were sufficiently characteristic to allow stages of development and cultivars and the wild species to be distinguished by principal component analysis and clustering. Many enzymes showed coordinated changes during fruit development of a given genotype. Comparison of the correlation matrices revealed a large overlap between the two modern cultivars and considerable overlap with S. pennellii, indicating that despite the very different development responses, some basic modules are retained. Comparison of enzyme activity, metabolite profiles, and transcript profiles in S. lycopersicum 'Moneymaker' revealed remarkably little connectivity between the developmental changes of transcripts and enzymes and even less between enzymes and metabolites. We discuss the concept that the metabolite profile is an emergent property that is generated by complex network interactions.

Tomato Fruit Photosynthesis Is Seemingly Unimportant in Primary Metabolism and Ripening But Plays a Considerable Role in Seed Development

“…While the role of fruit photosynthesis in fruit metabolism and development has been much discussed (Piechulla et al, 1987;Wanner and Gruissem, 1991;Schaffer and Petreikov, 1997;Alba et al, 2004;Carrari et al, 2006;Steinhauser et al, 2010), it has not yet been clearly experimentally defined. Early experiments aimed at addressing this question involved shading individual fruit with aluminum foil (Tanaka et al, 1974).…”

“…Tomato fruit clearly undergo a physiological transition on the differentiation of photosynthetically active chloroplasts into chromoplasts (Bü ker et al, 1998;Kahlau and Bock, 2008), and this transition would appear to be coupled to a decline in the expression (Piechulla et al, 1987;Wanner and Gruissem, 1991;Alba et al, 2004;Carrari et al, 2006;Kahlau and Bock, 2008) and enzymatic activities (Schaffer and Petreikov, 1997;Steinhauser et al, 2010) associated with carbon assimilation.…”

Identification of Enzyme Activity Quantitative Trait Loci in aSolanum lycopersicum×Solanum pennelliiIntrogression Line Population

“…However, it is not a universal rule, as several amino acids increased in the ILs but were lower in S. pennellii than in M82 (Schauer et al, , 2008. The behavior of enzyme activities at the ripe stage of development in S. lycopersicum and S. pennellii was described by Steinhauser et al (2010). While in the glycolysis and tricarboxylic acid pathway, enzyme activities are gen- Figure 5.…”

“…We have established a robot-based platform to determine the activities of over 30 enzymes from central metabolism in vitro in optimized conditions (Gibon et al, 2004;Steinhauser et al, 2010;Sulpice et al, 2010). Changes in measured activity in such conditions broadly reflect changes in the amount of protein for that enzyme (Piques et al, 2009).…”

Evidence for karyoplasmic homeostasis during endoreduplication and a ploidy-dependent increase in gene transcription during tomato fruit growth

“…Interestingly, an important remodelling of the transcriptome is tightly linked to endoreduplication in nitrogen-fixing nodules (Mergaert et al, 2003). As far as tomato fruit is concerned, only descriptive analyses for transcriptional and metabolic profiling in endoreduplicated tissues have been provided (Lemaire-Chamley et al, 2005;Mounet et al, 2009;Schauer et al, 2006;Steinhauser et al, 2010), without any direct link with the extent of endoreduplication.…”