Thermotolerance in seeds of a new oilseed crop Physaria fendleri (A. Gray) O’Kane & Al-Shehbaz and related species

Abstract

Tolerance to high temperature is a valuable trait in plants along with resilience to other abiotic stresses. We conducted 2 experiments to test the effect of varying high temperature treatments on the seed germination of Physaria fendleri (A. Gray) O'Kane & Al-Shehbaz (syn. Lesquerella fendleri [Brassicaceae]) and its relatives, P. argyraea (A. Gray) O'Kane & Al-Shehbaz, P. gordonii (A. Gray) O'Kane & Al-Shehbaz, and Paysonia grandiflora (Hook.) O'Kane & Al-Shehbaz (Brassicaceae). In one experiment, we examined the germination response of these species at 60 °C (140 °F), 80 °C (176 °F), and 103 °C (217 °F) for various lengths of time (0.5, 1,4, 12, 24, and 72 h), and in another experiment we focused on lower temperatures and smaller time increments at 85 °C (185 °F), 90 °C (194 °F), and 95 °C (203 °F) for 10, 20, 40, and 60 min. Results indicated significant differences in the germination percentages among species and temperature regimens. Seeds of P. grandiflora retained viability (3%) after 4 h at 103 °C (217 °F). Seeds of the other species retained high viabilities (67-89%) after exposure to 60 °C (140 °F) and 80 °C (176 °F) up to 72 h. These results demonstrate that these taxa have seeds that exhibit tolerance to extreme temperatures. The information may be useful for understanding the resilience of Paysonia and Physaria in wild habitats. Further investigation on this seed thermotolerance trait may have an impact on future crop improvement and germplasm conservation activities in Lesquerella and related Brassica species.