Tuber Storage Proteins

Abstract

A wide range of plants are grown for their edible tubers, but five species together account for almost 90 % of the total world production. These are potato (Solanum tuberosum), cassava (Manihot esculenta), sweet potato (Ipomoea batatus), yams (Dioscorea spp.) and taro (Colocasia, Cyrtosperma and Xanthosoma spp.). All of these, except cassava, contain groups of storage proteins, but these differ in the biological properties and evolutionary relationships. Thus, patatin from potato exhibits activity as an acylhydrolase and esterase, sporamin from sweet potato is an inhibitor of trypsin, and dioscorin from yam is a carbonic anhydrase. Both sporamin and dioscorin also exhibit antioxidant and radical scavenging activity. Taro differs from the other three crops in that it contains two major types of storage protein: a trypsin inhibitor related to sporamin and a mannose-binding lectin. These characteristics indicate that tuber storage proteins have evolved independently in different species, which contrasts with the highly conserved families of storage proteins present in seeds. Furthermore, all exhibit biological activities which could contribute to resistance to pests, pathogens or abiotic stresses, indicating that they may have dual roles in the tubers.

Isolation and in vitro identification of proteinase inhibitors from soybean seeds inhibiting helicoverpa gut proteases

“…PIs may also function as storage proteins (Mosolov et al 2001;Birk 2003;Shewry 2003). This assures the enough production ability of PI.…”

The impact of heat-moisture treatment on the molecular structure and physicochemical properties of normal and waxy potato starches

“…The amylose-lipid inclusion complex has been shown to influence the gelatinization temperature, granular swelling and solubility, amylose leaching, paste viscosity, retrogradation, and enzymatic hydrolysis (Debet and Gidley, 2006;Guraya e/ 01., 1997;Holm e/ 01.,1983;Hoover, 2010Hoover, ,1998Tester and Morrison 1990;Vasanthan and Hoover, 1992 (HooverandHadziyev, 1981), improving structural integrity in cereal kernels (parboiled rice) during cooking (Biliaderis eta!., 1993), increasing the free-thaw stability and an anti-staling effect in bread and biscuits (Riisom et ai., 1984), and improving the texture in products containing extruded starch (Mercier etai., 1980 Generally, a starch granule comprises a number of nitrogen fractions such asprotein,peptides, free amino acids, amides, enzymes and nucleic acids (Eppendorfer, 1979;Lineback and Rasper, 1988;Swinkels, 1985). Among these nitrogen fractions, pure protein represents on average about 50% of the nitrogen of potato tubers, and may range from 34% to 70% (Shewry, 2003).…”

Proteomic analysis of the potato tuber life cycle

“…On the other hand, individual members of the patatin gene family exhibit differential expression pat-terns depending on the tuber development stage [24]. Even though patatins are considered as storage proteins, lipase and b-1,3-glucanase activities have been described for them, indicating that patatins may play a role in defense reactions [25]. Proteins involved in protein synthesis and turnover, such as several chaperone proteins, were also prominent during the life cycle.…”