Root chicory (Cichorium intybus var. sativum) is a biennial plant that requires vernalization for flowering initiation. However, we previously showed that heat can induce root chicory flowering independently of vernalization. To deepen our understanding of the temperature control of flowering in this species, we investigated the impact of heat, vernalization and their interaction on flowering induction and reproductive development. Heat increased the flowering percentage of non-vernalized plants by 25% but decreased that of vernalized plants by 65%. After bolting, heat negatively affected inflorescence development, decreasing the proportion of sessile capitula on the floral stem by 40% and the floral stem dry weight by 42% compared to control conditions, although it did not affect the number of flowers per capitulum. Heat also decreased flower fertility: pollen production, pollen viability and stigma receptivity were respectively 25%, 3% and 82% lower in heat-treated plants than in untreated control plants. To investigate the genetic control of flowering by temperature in root chicory, we studied the expression of the FLC-LIKE1 (CiFL1) gene in response to heat; CiFL1 was previously shown to be repressed by vernalization in chicory and to repress flowering when over-expressed in Arabidopsis. Heat treatment increased CiFL1 expression, as well as the percentage of bolting and flowering shoot apices. Heat thus has a dual impact on flowering initiation in root chicory since it appears to both induce flowering and counteract vernalization. However, after floral transition, heat has a primarily negative impact on root chicory reproduction.

中文翻译：

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春化和热量对根菊苣 (Cichorium intybus L. var. sativum) 开花诱导、发育和育性的影响


根菊苣（Cichorium intybus var. sativum）是一种二年生植物，需要春化才能开花。然而，我们之前表明，热量可以独立于春化作用诱导根菊苣开花。为了加深我们对该物种开花温度控制的理解，我们研究了热量、春化及其相互作用对开花诱导和生殖发育的影响。热量使未春化植物的开花率提高了 25%，但使春化植物的开花率降低了 65%。抽苔后，热量对花序发育产生负面影响，与对照条件相比，花茎上无梗头状花序的比例减少了 40%，花茎干重减少了 42%，尽管它并不影响每个头状花序的花朵数量。热量还降低了花朵的育性：与未处理的对照植物相比，经过热处理的植物的花粉产量、花粉活力和柱头可受性分别降低了 25%、3% 和 82%。为了研究菊苣根部温度对开花的遗传控制，我们研究了 FLC-LIKE1 (CiFL1) 基因对热响应的表达。此前研究表明，CiFL1 在菊苣中受到春化作用的抑制，在拟南芥中过度表达时会抑制开花。热处理增加了 CiFL1 表达，以及抽苔和开花芽尖的百分比。因此，热量对根菊苣的开花起始具有双重影响，因为它似乎既诱导开花又抵消春化作用。然而，在花期转变后，热量主要对菊苣根的繁殖产生负面影响。