Salinity and proteolytic enzymes in germinating seeds of x Haynaldoticum sardoum (Poaceae)

The effect of salinity on germination, early seedling growth, and storage protein mobilization of x Haynaldoticum sardoum MELETTI & ONNIS seeds was investigated. Increased salinity affected more adversely the early germination of the Culmo Pieno than Culmo Vuoto line seeds - the higher the temperature the greater the effect. The reduction in coleoptile and root growth appeared to be more sensitive to increased salinity than germination; minor differences between Culmo Pieno and Culmo Vuoto seedlings were found. The activity of some proteolytic enzymes involved in the mobilization of the endospermatic storage proteins was estimated: high salinity generally reduced the proteolytic activity. The inhibition of cysteine proteinase (EC 3.4.22) activity was particularly interesting since this enzyme was involved in the initial and further degradation of gluten, and appeared to play a key role in that process. The consequence of this inhibition could lead to the impaired capacity of the seed to mobilize storage proteins, and hence deprive young seedlings of nutrients prior to the development of the autotrophic capacity.