Selection of cold tolerant cells of grapes in suspension culture

Abstract

Suspension cultures of three cultivars of grape hybrids ( Vitis spp.) were used to select cold tolerant cell lines. The cultured cells were cooled at 2°C/h to various temperatures below the average lethal temperature (LT 50) of the cell population. The cold tolerant lines were selected based on the distribution of lethal temperatures in the population. The small fractions of cells which were more cold tolerant than the LT 50 of the population were enriched by a two step selection process. After the first step, the cold tolerant lines of all three cultivars survived −7°C (LT 50), whereas the control population survived between −2.5 and −3.2°C. The cells selected −3 and −5°C were tolerant to temperatures as low as −6°C. During the second selection step, the selected lines (LT 50; −7 to −7.3°C) were used to isolate and enrich the cell population that survived between −9 and −9.6°C. The increased cold tolerance in selected lines was due to shifts in the frequency and distribution of lethal cell injury in the selected population as compared to the unselected control.