In most plant species, initiation of lateral roots occurs above the elongation zone. However, in Cucurbitaceae it takes place in the parental root meristem. Ilina et al. investigate the first cellular events leading to lateral root initiation in Cucurbita pepo roots and the participation of auxin in this process.
Fluorescent reporters under control of the DR5 promoter are used for the visualization of cellular auxin response maxima in transgenic squash roots. The results show that the formation of a local auxin response maximum before the first anticlinal formative divisions is the common mechanism of lateral root initiation in flowering plants.
Ilina, E. L., Kiryushkin, A. S., Semenova, V. A., Demchenko, N. P., Pawlowski, K., & Demchenko, K. N. (2018). Lateral root initiation and formation within the parental root meristem of Cucurbita pepo: is auxin a key player? Annals of Botany. https://doi.org/10.1093/aob/mcy052