Cyclin gene SlCycB1 alters plant architecture in association with histone H3.2 in tomato

Cell cycle regulation plays a critical role in plant growth and development. In this study, the role of a tomato cell cycle gene SlCycB1 has been characterized. Expression analysis revealed that SlCycB1 was mostly expressed in stem, root, and leaves, with relative lower expression in flower and fruit. Tomato plants overexpressing SlCycB1 exhibited a reduction in cell number and increased cell size leading to the growth retardation. Furthermore, yeast two-hybrid analysis and bimolecular fluorescence complementation revealed that SlCycB1 interacted with histone H3.2, an essential component of the nucleosome. Histone H3.2 was transcriptionally up-regulated in the SlCycB1 overexpressing tomato lines. Furthermore, the overexpression of histone H3.2 in transgenic plants showed similar phenotypes to SlCycB1 overexpressing lines. Based on these findings, we concluded that SlCycB1 overexpression altered tomato architecture in association with histone H3.2.