ISHS Acta Horticulturae 789: XV Meeting of the EUCARPIA Tomato Working Group
PLEIOTROPIC EFFECT IN THREE ANTHOCYANINLESS TOMATO MUTANTS |
| Authors: | E. Balacheva, L. Shtereva, B. Atanassova, E. Mollе |
| Keywords: | seed germination, optimal and stress conditions, Lycopersicon esculentum |
| Abstract:
Anthocyanin pigmentation in tomato is best visualized in hypocotyls, and a number of mutations that alter the intensity or distribution of anthocyanin pigmentation has been identified. Three of these mutations – anthocyaninless of Hoffmann (ah), anthocyanin without (aw) and baby lea syndrome (bls) – were found not only to completely inhibit anthocyanin biosynthesis, but also to be associated with alterations in seed morphology and testa histochemistry. This pleiotropic effect and especially the absence of condensed tannins in the seed coat were found to lead to a number of secondary effects concerning important seed characteristics. A strong correlation between germination responses, kinetics of water uptake and testa composition of the genotypes studied was detected. Seeds of ah-, aw- and bls-genotypes, that were characterized by absence of tannins in their seed coats, took up increased amounts of water and germinated more rapidly under optimal and stress condition in comparison with the wild type genotypes that were characterized by presence of tannins in their testa. On the other hand, it was found that after four and more years of storage the viability (expressed as time to 50% germination and final percentage of germination) of the ah, aw and bls mutant seeds decreased more rapidly than that of the wild type. It is known that condensed tannins contribute to the rigidification of cell structure; therefore, their absence in the seed coat could contribute to its increased permeability that subsequently could lead to the more rapid water uptake and enhanced germination observed in the mutant seeds. This finding gives reasons to assume that the phenomenon might serve as a new tool for breeding tomato genotypes tolerant to stress at germination based on morphological markers that would significantly facilitate the breeding process. At the same time breeders should take into consideration that the lack of condensed tannins in the mutant testa not only contributes to enhanced germination but also leads to a more rapid reduction of vigor and viability of aged mutant seeds in comparison with those of the wild type. | |
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