Meccanismi fisiologico-molecolari di germinazione in specie spontanee

Seed dormancy provides a mechanism for plants to delay germination until conditions are optimal for survival of the next generation. Knowledge of dormancy release and dormancy induction requirements is important to increase our understanding about the entire process. Furthermore, to assess the association between gene expression patterns and physiological phase in dormancy is a major goal to allow a positive definition of this condition. In Chrysanthemum coronarium var. concolor and var. discolor, anatomical and germination analyses showed that non-deep physiological dormancy (PD) is the more plausible type of dormancy for both of them. The genetic composition of Chrysanthemum coronarium varieties was characterized using Inter Simple Sequence Repeat (ISSR) PCR together with a DNA-Barcoding approach. Seed priming treatments were used in a non-dormant species, Leucanthemum vulgare, to induct secondary dormancy at specific temperature range and a long-priming treatment was used for its release. Fluridone and giberellic acid were tested to investigate the metabolic pathway involved in the onset of secondary dormancy and in its maintenance. Five probable housekeeping genes, useful as reference genes for quantitative PCR (qPCR) analysis in seed tissue, were identified in Chrysanthemum coronarium and in Leucanthemum vulgare, isolated and confirmed with comparative analysis with homologous genes in model species. One radicle-protrusion associated gene, EXP (Expansin), was identified in the two species, isolated and confirmed. Three dormancy-associated genes, DOG1 (Delay Of Germination 1), FLC (Flowering Locus C), HUB2 (Histone Mono-Ubiquitination 2) were identified in Chrysanthemum coronarium and in Leucanthemum vulgare.