Pak choi is a low-temperature vernalized plant that readily undergoes premature bolting during spring, but little is known about the governing molecular regulation of vernalization. In order to enhance our understanding of mechanism about premature bolting, we discussed the relationship between auxin (indole-3-acetic acid, IAA) and flowering of pak choi. During vernalization, hormone metabolism is an important regulatory pathway, and IAA plays a specific role. IAA metabolism has been studied in Arabidopsis thaliana and other plants, but not in pak choi. In this paper, the IAA content in pak choi shoot apices during vernalization and different growth stages was compared. The IAA content decreased significantly after low-temperature treatment (4 °C) and then increased rapidly during vegetative growth. During floral bud initiation, the IAA content decreased rapidly and was the lowest. Expressions of genes encoding key IAA metabolic enzymes were analyzed, and a major synthetase-encoding gene was downregulated, while a key degrading enzyme-encoding gene was upregulated during each comparison period, resulting in decreased IAA content. Expressions of four genes (Bra034975, Bra030246, Bra012239 and Bra040296) were consistent with changes in the IAA content. The functions of differentially expressed genes (DEGs) were analyzed, and 15 DEGs were found to be related to IAA metabolism. The findings illuminated the molecular mechanism regulating IAA content during vernalization in pak choi.

小白菜是一种低温春化植物，在春季很容易发生早,，但对春化的分子调控却知之甚少。为了加深我们对过早锚定机理的理解，我们讨论了生长素（吲哚-3-乙酸，IAA）与小白菜开花之间的关系。在春化期间，激素代谢是重要的调节途径，而IAA发挥特定作用。在拟南芥中研究了IAA代谢和其他植物，但不在白菜中。在本文中，比较了春化和不同生长期的小白菜尖中IAA含量。低温处理（4°C）后，IAA含量显着下降，然后在营养生长过程中迅速上升。在花芽萌芽过程中，IAA含量迅速下降并且是最低的。在每个比较期间，分析了编码关键IAA代谢酶的基因的表达，下调了主要的合成酶编码基因，而上调了关键的降解酶编码基因，导致IAA含量降低。四个基因（Bra034975，Bra030246，Bra012239和Bra040296）的表达）与IAA内容的更改保持一致。分析了差异表达基因（DEG）的功能，发现有15个DEG与IAA代谢有关。这些发现阐明了白菜春化过程中调节IAA含量的分子机制。