Abstract Cichorium intybus is a biennial plant species forming a taproot and a leaf rosette during the first year and which requires low temperature during vernalization to flower during the second year of its cycle. Heat stress, however, is known to induce premature flowering during the first year. The present work aims to compare the effect of heat treatment (38 °C during 3 days) and vernalization (4 °C during 6 weeks) on the phytohormonal profile and the expression of two chicory genes (CiFL1 and CiFT) homologous to the Arabidopsis flowering genes FLOWERING LOCUS C (FLC) and FLOWERING LOCUS T (FT). In Arabidopsis, FLC and FT code, respectively, for a repressor and an activator of flowering. Although CiFL1 was inhibited by vernalization, its expression was increased by heat treatment in both vernalized and non-vernalized seedlings while high temperature unexpectedly inhibited FT expression in vernalized seedlings. Vernalization induced a modification in the hormonal profile of C. intybus (cv. Melci) in a sense of a decrease in ethylene production, abscisic acid and total jasmonates content, while the level of salicylic and benzoic acids as well as polyamine spermidine increased. A limited effect on the gibberellins’ profile was observed. The subsequent impact of heat stress on phytohormone content was different in non-vernalized and vernalized seedlings, with a higher abscisic acid and jasmonates and a lower 1-aminocyclopropane-1-carboxylic acid concentration in the former than in the latter. These data are discussed in relation to the putative involvement of phytohormones in stress-induced flowering. It appears that heat stress implies different pathways than vernalization to hasten flowering process.

中文翻译：

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高温下菊苣幼苗中植物激素谱和 CiFL1 表达与春化和去春化过程的关系

摘要 Cichorium intybus 是二年生植物，第一年形成主根和莲座丛，春化时需要低温，第二年开花。然而，已知热应激会导致第一年过早开花。目前的工作旨在比较热处理（38°C，3 天）和春化（4°C，6 周）对植物激素谱和与拟南芥开花同源的两种菊苣基因（CiFL1 和 CiFT）表达的影响。基因 FLOWERING LOCUS C (FLC) 和 FLOWERING LOCUS T (FT)。在拟南芥中，FLC 和 FT 分别编码为抑制因子和激活因子。尽管 CiFL1 被春化抑制，通过热处理在春化和非春化幼苗中其表达增加，而高温出乎意料地抑制了春化幼苗中的 FT 表达。在乙烯产量、脱落酸和茉莉酸总含量减少的意义上，春化诱导了 C. intybus (cv. Melci) 的激素谱发生改变，而水杨酸和苯甲酸以及多胺亚精胺的水平增加。观察到对赤霉素谱的有限影响。热应激对植物激素含量的后续影响在非春化和春化幼苗中有所不同，前者的脱落酸和茉莉酸含量较高，而 1-氨基环丙烷-1-羧酸的浓度低于后者。这些数据与植物激素在应激诱导的开花中的假定参与有关。似乎热应激意味着与春化不同的途径来加速开花过程。