The mechanism of newly differentiated leaves of kale turning white in late autumn

ABSTRACT Newly differentiated leaves of albino ornamental kale turn white as exposed to low temperatures, producing a distinctive and commercially desirable unique color pattern. Here, we show that this low‐temperature‐induced albinism is caused by a mutation in the kale F‐box gene BoWl . Using yeast two‐hybrid, pull‐down, co‐immunoprecipitation, and luciferase complementation assays, we demonstrate that BoWl interacts with the transcription factor BoARF1 to form a functional complex. Complementary yeast one‐hybrid, electrophoretic mobility shift, chromatin immunoprecipitation, and luciferase assays reveal that this complex activates BoGLK1 , a regulator of chloroplast development and chlorophyll synthesis. In the albino line, a mutation in BoWl results in abnormal chloroplast structure and disrupts chlorophyll synthesis. We further identify BoCBF1/BoPHL2 as a low‐temperature responsive regulatory module that transcriptionally activates BoWl expression. Together, these findings define a molecular pathway linking cold perception to transcriptional regulation associated with leaf whitening in ornamental kale, providing new insight into how low temperature influences genetically controlled leaf color variation.