High regrowth of potato crop wild relative genotypes after cryogenic storage.

Potatoes are consumed by millions of people and are the survival food in several countries. Cultivated varieties of potato (Solanum tubersosum L.) are results of selection and crossing of many wild species. Only 8-13% of wild potato species used for food are preserved by either in situ or ex situ methods. The U.S. National Potato Germplasm Collection maintains over 5900 accessions, of which 75% are crop wild relatives (CWR). The objective of the study was to investigate regrowth of cryogenically stored clonal propagules (shoot tips) of selected CWR accessions maintained in the collection. Sixty-nine accessions from 30 Solanum species and six accessions that are not yet assigned to a species were cryopreserved by a droplet vitrification method at the NLGRP. The post cryopreservation regrowth varied from 40 to 100% (average 68%) but was not significantly different between the tested accessions. Regrowth of six accessions tested after 10 years of cryogenic storage was between 35 and 90% (average 66%) and was significantly different from their initial regrowth (average 87%); the largest viability loss was in S. condolleanum; but for the other five accessions the regrowth was between 45 and 90% (average 72%) and suggested at least 10 years of successful storage in LN was possible. Twelve potato wild species cryopreserved in this study were reported in literature as important for developing cultivated varieties for changed weather conditions.

Antiproliferative activity and cytotoxicity of Solanum jamesii tuber extracts on human colon and prostate cancer cells in vitro.

Some tuber-bearing wild potato species are reportedly higher in potential health-promoting traits, such as antioxidant activity (AOA) and total phenolic content (TP), than commercial cultivars; therefore, they could be used as parental material in breeding for high AOA and TP. However, using wild species might result in progenies that are toxic for human consumption because of the presence of high total glycoalkaloids (TGAs) and other unknown compounds. Therefore, wild potato accessions should be screened for cytotoxicity before their introduction into breeding programs. The objective of this study was to investigate antiproliferative activity and cytotoxicity of tuber extracts from 15 Solanum jamesii accessions on human HT-29 colon and LNCaP prostate cancer cell lines in vitro. Also, correlations among AOA, TP, TGA, and antiproliferative activity were determined. The tuber extracts significantly inhibited proliferation of HT-29 and LNCaP cell lines and were not cytotoxic to the cells compared to the control (DMSO). The antiproliferative activity exhibited by tuber extracts was not due to necrosis, because the amount of lactate dehydrogenase (LDH) released from cells incubated with the extracts was not significantly different from that released from cells incubated without extracts (control). Colon cancer cells were more responsive to tuber extract treatment than prostate cancer cells. In both HT-29 and LNCaP cells, there were no observable significant correlations between antioxidant activity (DPPH and ABTS) and inhibition of cell proliferation or between TP and cell proliferation inhibition. Also, glycoalkaloids did not exhibit significant correlations with the inhibition of cancer cell proliferation. Findings of this study show that S. jamesii accessions probably pose no cytotoxic effects when used as parental material in improving the nutritional value of potato cultivars. Correlation results, along with cell proliferation data, suggest that not only the compounds measured in this study but also other bioactive compounds present in the matrix acting additively or synergistically may be more responsible for the antiproliferative effects of potato tuber extracts than higher concentrations of a single or group of compounds.