Explorations into Starch Properties of Mirabilis spp. (Nyctaginaceae); DSC Results for Endangered Andean M. expansa, TEM of M. jalapa Seed

Abstract

Explorations into the starch properties of two species of Mirabilis (Nyctaginaceae) was the focus of preliminary research. Andean Mirabilis expansa (Ruiz and Pav.) Standl. includes the wild type, and an endangered, indigenous crop derived from it. No varieties of the crop are known to be patented or in commercial use. Mexican M. jalapa L. has been manipulated horticulturally since pre-Columbian times, is grown internationally for its flowers today, and is also known as a weed throughout the topics. Differential Scanning Calorimetry (DSC) was applied to starch derived from both lyophilized and air-dried material from two varieties of M. expansa, for this study. M. expansa starch samples from both varieties, submitted for DSC, were extracted from above and below ground rhizomes, roots and stems, that were enlarged with material stored by growing plants. Transmission Electron Microscopy (TEM) was used to examine seed starch from M. jalapa. Starch from both M. expansa varieties was shown to be competitive with cassava starch in the DSC study. Lyophilized material contained considerably more of the starch than air dried pieces of the same type. In addition, TEM of M. jalapa seed, revealed starch granules consistently 1-2 µm in diameter. The need to develop the crop, improve protection for ancient crop varieties and the wild type, breed new disease resistant varieties, and for research on the starch's food and commercial potential, is also considered. Included is our perspective on issues surrounding funding for further research on M. expansa, and for other indigenous crops with no previous history as modern crops.