Multiple enzyme forms of tomato seeds and seedlings

Abstract

Proteins were extracted from dormant seeds, germinating seeds, and 12-day-old seedlings of Chico I11 and Homestead-24 tomato cultivars. Disc gel electrophoresis of the crude extracts showed that the number of enzyme forms differed with developmental stage of each cultivar. Generally the number of enzyme forms was greater in seedlings than in dormant seeds; exceptions were the numbers of enzyme forms of catalase and malic dehydrogenase, which decreased. In Homestead-24, the number of general protein forms was greater in seedlings than in dormant seeds. In Chico 111, the number of protein forms was the same in dormant seeds and seedlings. The number of protein forms was lowest a t the germinating seeds stage of both cultivars. Differences between the enzyme activities of the two cultivars were detected.Seeds contain two types of proteins: metabolic proteins, both enzymatic and structural, which are concerned with cellular activities, and a second type, the storage or reserve proteins. Many of the former exist in multiple molecular forms known as isoenzymes. The latter have no enzymatic activity (Varner, 1965; Atschul e t al., 1966). Both types of proteins function after promotion of seed germination. Reserve proteins are hydrolyzed by enzymatic proteins, and the degradation products are a source of nitrogen and carbon for the developing seedling (Oota e t al., 1953).Disc gel electrophoresis has been the most convenient method for the resolution of protein mixtures. Isoenzymes present in seed tissue (Cherry and Ory, 1973; Macko et al., 1967) and in other plant tissues (Kadam e t al., 1973; Hall e t al., 1969) have also been resolved into distinct patterns by this technique. Numerous studies of enzyme activities in tomato fruit have been reported (Lee and MacMillan, 1968; Nakagawa Food Crops Utilization Research Laboratory, Subtropical Texas Area, Southern Region, Agricultural Research Service, US. Department of Agriculture, Weslaco, Texas 78596. et al., 1970;Hobson, 1967Hobson, ,1974 and most concerned the enzymatic changes associated with ripening. Only few investigations have dealt with the identification of enzyme forms present in tomato seeds and seedlings and the changes those enzyme forms undergo during seed germination. A fundamental knowledge of the enzyme forms present in seeds and seedling would allow a better understanding of the biochemical steps that accompany the development of the plant. Any differences in enzyme distribution among varieties might enable the screening of plant crops for factors such as disease resistance and agronomic performance.We undertook to identify and compare the enzyme forms of dormant seeds, germinating seeds, and seedlings of a firm (Chico 111) and a soft (Homestead-24) variety of tomato, and to determine whether firmness of fruit could be related to the electrophoretic patterns of enzymes from plants a t an early stage of development. We investigated the enzyme forms of acid and alkaline phosphatase, esterase, catalase, peroxidase, and malic dehydrogenase (MDH). Of these,...

Electrophoretic analyses of selected enzymes from tomato cultivars with different fruit maturation

“…However, the presence of several enzyme systems in developing tomato fruit has been revealed by disc gel electrophoresis (Hobson, 1974). Several of these enzyme systems were reported to be present in dormant seeds and young tomato seedlings (Stein and Lime, 1978). Since many enzymes are in multiple molecular forms within a single cell, certain enzyme systems have been investigated in depth with respect to their physiological roles in fruit ripening (Hobson, 1974;Hulme, 1972).…”