Collaborative expression of FLOWERING LOCUS C in heat-tolerant cauliflower

Abstract

Introduction – Cauliflower (Brassica oleracea var. botrytis) is suitable for growing in a temperate climate and could be grown in tropical or sub-tropical regions in the cool season. Due to the impact of global warming, cauliflower cultivation has become a challenge. At temperatures over 30 °C, the curds show physiological disorders resulting in low quality and economic loss. The study aimed to determine the curd development and FLOWERING LOCUS C (FLC) gene expressions in heat-tolerant and non-heat-tolerant cauliflower, which could provide helpful information for cauliflower selection in the future. Materials and methods – Cauliflower seedlings were treated at 26 °C in growth chambers for two weeks. After the stem apices reached curd initiation, plants were exposed to continuous temperatures of 26, 30, and 34 °C for 5 weeks. BoFLC gene detections were in the 2nd and 4th weeks after temperature treatments. In the 3rd and 5th weeks, apex investigations were conducted by tissue dissection with microscope observation. Results – Cauliflower ‘Winner’ showed heat tolerance at 26 °C and 30 °C, and curd development was induced. BoFLC1, BoFLC2, and BoFLC5 transcript levels decreased after curd initiation. ‘Early 45’ also formed visible curd at 26 °C with decreasing BoFLC1 and BoFLC2 transcript levels and the lowest level of BoFLC5. The high BoFLC1 and BoFLC5 in ‘PI 244664’ acted as a potent inhibitor at the curd development stage at 26–34 °C. Conclusion – BoFLC in heat-tolerant lines might go through a collaborative expression via the non-vernalization pathway and establish an adaptive mechanism at relatively high temperatures (26–30 °C).