First published online March 25, 2008; 10.1105/tpc.108.200313
The Plant Cell 20:501
Heritability of the Tomato Fruit Metabolome
Nancy A. Eckardt
News and Reviews Editor
neckardt{at}aspb.org
Agricultural crop varieties contain only a small amount of the variation present in the gene pool that includes their closely related wild relatives, and wild relatives are therefore considered to be a valuable resource for continued improvements in crop yield and quality (Fernie et al., 2006 ). Working in tomato, Schauer et al. (2006) used metabolite profiling combined with introgression breeding from an interspecific cross between cultivated Solanum lycopersicum and its wild relative S. pennellii to identify a large number of quantitative trait loci (QTL) affecting metabolite accumulation in tomato fruit. In this issue, Schauer et al. (pages 509–523) extend these studies by examining fruit metabolite levels in an additional year's harvest and analyzing additional lines heterozygous for the introgression of chromosomal segments from S. pennellii. This study focused on investigating the mode of inheritance of metabolic QTL and the consequences of mode of inheritance with respect to the breeding of specific traits. The authors also looked for evidence of heterosis (hybrid vigor) at the metabolite level, especially since Schauer et al. (2006) previously found that the increased metabolite content was associated with decreased yield in the majority of cases.
Using a more stringent threshold than applied in the previous study, the authors identified 332 putative metabolic QTL. They found that the majority of the putative wild species QTL showed an increasing effect on metabolite content relative to the reference cultivated S. lycopersicum line and were inherited in a dominant or additive manner (see figure). In addition, the strong negative association between yield and metabolite content previously observed in lines homozygous for the S. pennellii introgressions (Schauer et al., 2006) was no longer apparent in heterozygous introgression lines. Although there was little indication of heterosis at the metabolite level, morphological parameters linked to yield were less tightly associated to metabolic traits in the heterozygous lines than they were in the homozygous introgression lines. These results suggest that introgression breeding might be a useful approach for engineering enhanced metabolic traits into crop species such as tomato. The work of Fernie et al. represents a valuable, comprehensive data set comprising several years of harvest and clearly shows the importance of repeated cultivation and analysis for introgression analyses.
View larger version (27K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Distribution of QTL mode of inheritance for metabolite accumulation. Bars represent the number of QTL for a specific amino acid, colored according to mode-of-inheritance categories: R, recessive; A, additive; D, dominant; and ODO, overdominant. Bars extending to the right or left of the 0 line represent increasing and decreasing QTL, respectively, in the introgressed line relative to the reference line of cultivated S. lycopersicum. QTL for other metabolites, including organic acids, sugar alcohols, sugars, and phosphates, followed a similar pattern (Schauer et al., 2008).
|
|
Footnotes
www.plantcell.org/cgi/doi/10.1105/tpc.108.200313
REFERENCES
Fernie, A.R., Tadmor, Y., and Zamir, D. (2006). Natural genetic variation for improving crop quality. Curr. Opin. Plant Biol. 9: 196–202.[CrossRef][ISI][Medline] Schauer, N., Semel, Y., Balbo, I., Steinfath, M., Repsilber, D., Selbig, J., Pleban, T., Zamir, D., and Fernie, A.R. (2008). Mode of inheritance of primary metabolic traits in tomato. Plant Cell 20: 509–523.[Abstract/Free Full Text] Schauer, N., et al. (2006). Comprehensive metabolic profiling and phenotyping of interspecific introgression lines for tomato improvement. Nat. Biotechnol. 24: 447–454.[CrossRef][ISI][Medline]
Related articles in Plant Cell:
- Mode of Inheritance of Primary Metabolic Traits in Tomato
- Nicolas Schauer, Yaniv Semel, Ilse Balbo, Matthias Steinfath, Dirk Repsilber, Joachim Selbig, Tzili Pleban, Dani Zamir, and Alisdair R. Fernie
Plant Cell 2008 20: 509-523.
[Abstract]
[Full Text]
|
|
