Dynamics of biochemical and hormonal reserves degradation in immature seeds of Euterpe edulis Martius (Arecaceae) during in vitro germination

Euterpe edulis Martius, popularly known as juçara, is a palm tree native to the Atlantic Forest. The fruits are rich in reserve compounds. This feature makes juçara seeds useful for assessing the mobilization and degradation of reserves, as well as the physiological, biochemical, and hormonal fluctuations that occur during germination and seedling development. The objective of this study was to characterize the degradation of reserves following in vitro germination, and to associate this degradation with the physiological quality of E. edulis seeds and seedling formation. Samples were germinated for 0, 10, 20, 30, 40, 60, 120, and 180 days. All morphological variables except seed dry mass increased during this period. Proteins were the first reserve compounds to be metabolized and were closely linked to germination. The hormones zeatin, indole-3-acetic acid, and abscisic acid were associated with the onset of germination. The ethylene precursor 1-aminocyclopropane-1-carboxylic acid, the polyamines spermine, spermidine, and putrescine, and the amino acid proline were required for germination and seedling formation. In summary, the metabolites resulting from the degradation of E. edulis seed reserves are destined for germination and seedling growth until senescence of the haustorium signals the end of this period. Key message Primary and secondary compounds related to germination and seedling formation in juçara seeds were quantified for the first time and demonstrated high conversion of reserves into seedling tissues.