Trigonelline inheritance in the interspecific cross between Coffea pseudozanguebariae x Coffea liberica var. Dewevrei
Coffee trees are characterised by the presence of the trigonelline alkaloid in their beans. During roasting, trigonelline leads to major coffee aroma compounds (several alkyl-pyridines and pyrroles). In the present study, the genetic inheritance of trigonelline accumulation, in green beans, was investigated in an interspecific cross between a wild East African species C. pseudozanguebariae (PSE) and the formerly cultivated West African species C. liberica dewevrei (DEW) (the two species are allogamous). Trigonelline content was measured by HPLC in both parental species, F1 and reciprocal backcross hybrids (BCDEW and BCPSE). Objectives were i) to evaluate trigonelline content in green beans of parental species and hybrids, ii) to estimate between year variation, iii) to analyse the genetic inheritance of its content and iv) to map QTL(s) for trigonelline. Main results concerning genetic inheritance: 1. Trigonelline was 0.57% in DEW and 1.02% in PSE and within-species range did not overlap. Between-tree variation existed also within species. 2. There was neither between-year variation nor interaction "between-year x tree". 3. Trigonelline contents were similar in PSE, F1, BCDEW and BCPSE, i.e. in groups with PSE cytoplasm. 4. Between-tree variation was emphasised in F1 showing also the presence of nuclear genes. Main results concerning trigonelline QTL analysis: 1. A QTL was located on the G genetic linkage group of the map developed in Ky et al. (2000), near the ACTCAT5 AFLP locus (LOD score=3.56) (Figure 1). 2. In BCDEW hybrids, there were two genotypes at the locus ACTCAT5: [tt] as for DEW and [Tt] as for F1 in a 1: 1 ratio (54% vs 46%). These two genotypes differed by their trigonelline average contents: 0.86% and 1.11%, respectively. 3. Distribution study within [tt] and [Tt] classes showed recombination events between the ACTCAT5 locus and the QTL. Two alleles of the QTL were defined: T for PSE and t for DEW. 4. Average contents differed between [tt] and [T1] classes: 0.83% and 1.20%, respectively. 5. The [tt] class average content was equal to (DEW + PSE)/2 showing additivity between nuclear and cytoplasmic effects. Conclusions: The importance of these results with respect to breeding is tbree-fold; i) trigonelline content can be increased in cultivated coffee using PSE as female parent and its cytoplasm in the next generations; ii) marker-assisted selection could be used in further backcross generations. MAS, at the plantlet stage, will avoid having to install large progeny populations in the field; iii) the existence of a small environmental effect and between-tree variations within [tt] and [Tt] groups, similar to the within-species variation, should facilitate clonal selection between hybrids.
| Main Authors: | , , , , |
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| Format: | conference_item biblioteca |
| Language: | eng |
| Published: |
ASIC
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| Subjects: | F30 - Génétique et amélioration des plantes, Q04 - Composition des produits alimentaires, |
| Online Access: | http://agritrop.cirad.fr/485921/ |
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