Changes in carbohydrate composition in seeds of three tropical tree species submitted to drying and storage at freezing temperature

Desiccation tolerance is a limitation to seed storage and conservation of plants. Reserve compounds of seeds have an important role in cellular protection against drying and freezing and in seed longevity. There are species differences in both tolerance to water loss and longevity, therefore we have compared the content and composition of non-structural carbohydrates among seeds of three tropical tree legumes: the desiccation sensitive Inga vera and the desiccation tolerant Caesalpinia echinata and Erythrina speciosa, with increasing degrees of longevity, respectively. After drying to different levels, the seeds were stored at -18 degrees C for 30 days before analysis. Higher cyclitol levels were found in C. echinata seeds, in contrast to I. vera. Additionally, higher amounts of sucrose, raffinose and stachyose were present in seeds of C. echinata, with markedly higher levels of raffinose and stachyose in E. speciosa. An increase in these sugars after drying and storage at -18 degrees C was associated with the increasing tolerance of C. echinata and E. speciosa seeds to drying and freezing, suggesting that sugar metabolism is crucial for the storage behaviour of those seeds.