Abstract text: The stem is an important organ that supports the above-ground parts of a plant and determines the arrangement of leaves and flowers. Recently, we found that stem cracking occurs in some of the Arabidopsis thaliana della mutants; however, the underlying mechanism remains unclear. To examine the potential influence of environmental factors on the frequency of stem cracking, we checked the growth of wild-type and della mutants under three types of white light sources with different spectral compositions, and observed both the external and internal morphology of their stems. As a result, both stem elongation and internal morphology differed depending on the light source, and the tendency for stem cracking in della mutants also varied with the light conditions. In addition, under certain light condition, we detected specific differences in secondary cell wall–related sugars in stem sugar profiles and in the expression of genes involved in gibberellin degradation.

Together, these results suggest that although the della mutation is a requirement for triggering stem cracking, the effect of the light source acts synergistically with it to influence crack formation.