This work is based on the study of the above- and below-ground tissues collected throughout a year, of the autumn-flowering geophyte Cyclamen graecum Link (Primulaceae). The geophytes are life forms that include underground storage organ reserves that support the initiation of leaf growth and flowering [1, 2, 3]; their buds, resposible for their annual growth, remain protected below the soil surface on an underground perennial organ and their growing and flowering period alternates with a period of dormancy. The purpose of this study is to estimate the seasonal fluctuation of sugars, starch and proline that contribute to the adaptation of C. graecum to the Mediterranean ecosystem. Α considerable amount of substances are allocated to leaves via transfer from root resources, photosynthates and senescing inflorescences. The total sugar content was determined using a modified phenol-sulphuric acid method. Quantitative determination of starch content was accomplished in sugar-free aliquots of dried tissues, which were solubilized in perchloric acid and the starch content was estimated using a modified anthrone method. Proline content was determined with acid-ninhydrin method. The above ground tissues of C. graecum that are exposed to ambient environmental conditions may exhibit seasonal responses to abiotic stresses. Ιt seems likely that monthly fluctuations of proline accumulation, sugars and starch content obtained in the above- and below-ground tissues of C. graecum coincide with the distinct seasonality of the ecosystem. The highest sugar content, among the considered plant parts, was detected in the tubers, whereas the lowest in peduncles and petals in late autumn. Relatively elevated sugar content was detected in the leaves from December to April, probably associated with constraints of the vegetative growth of this species. Throughout the flowering period of C. graecum (September-December), similar trends of sugar content were detected between petals and peduncles. Starch is stored in tubers and leaves of C. graecum and the elevated values from March to April coincide with elevated photosynthetic rates. The accumulation of sugars and proline in petals from September to December may result to a reduction of their osmotic potential, which is expected to maintain their turgor and avoid the harmful effect of the cold period. Additionally, the pronounced proline accumulation in expanded leaves of C. graecum from November to April indicates the protective role of proline in tissues exposed to ambient environmental conditions

References

1. Dafni A., Cohen D., & Noy-Mier I. (1981). Life-cycle variation in geophytes. Annals of the Missouri Botanical Garden, 68(4), 652-660.
2. Negbi M. (1989). Theophrastus on geophytes. Botanical Journal of the Linnean Society 100(1), 15-43.
3. Akita Y., et al. (2010). Comparative analysis of floral pigmentation between wild-type and white-flowered varieties of Cyclamen graecum. The Journal of Horticultural Science and Biotechnology 85(5), 437-443.