Lateral roots, in addition to adventitious roots, form a barrier to radial oxygen loss in <i>Zea nicaraguensis</i> and a chromosome segment introgression line in maize
Ole Pedersen, Yohei Nakayama, Hiroki Yasue, Yusuke Kurokawa, Hirokazu Takahashi, Anja Heidi Floytrup, Fumie Omori, Yoshiro Mano, Timothy D. Colmer, Mikio Nakazono
Abstract
Summary Plants typically respond to waterlogging by producing new adventitious roots with aerenchyma and many wetland plants form a root barrier to radial O 2 loss (ROL), but it was not known if this was also the case for lateral roots. We tested the hypothesis that lateral roots arising from adventitious roots can form a ROL barrier, using root‐sleeving electrodes and O 2 microsensors to assess ROL of Zea nicaraguensis , the maize ( Zea mays ssp. mays ) introgression line with a locus for ROL barrier formation (introgression line (IL) #468) from Z. nicaraguensis and a maize inbred line (Mi29). Lateral roots of Z. nicaraguensis and IL #468 both formed a ROL barrier under stagnant, deoxygenated conditions, whereas Mi29 did not. Lateral roots of Z. nicaraguensis had higher tissue O 2 status than for IL #468 and Mi29. The ROL barrier was visible as suberin in the root hypodermis/exodermis. Modelling showed that laterals roots can grow to a maximum length of 74 mm with a ROL barrier, but only to 33 mm without a barrier. Presence of a ROL barrier in lateral roots requires reconsideration of the role of these roots as sites of O 2 loss, which for some species now appears to be less than hitherto thought.