A Maize Mutant with an Altered Vascular Pattern

A recessive maize mutant with disrupted seedling developmentwas isolated following transpositional mutagenesis with Mutator.This mutant, initially identified during germination on thebasis of abnormal growth of the scutellar node, was designatedlsn1 (l arge s cutellar n ode). The mutant seedling exhibitsan enlarged primary root with a longitudinal groove and multipleseparate root tips. The mutant root is shorter than normal,because of defective cell elongation, and lacks lateral roots.The mutant plant shows defective leaves and reduced internodeelongation. Histological analyses on primary root, shoot, scutellarnode and juvenile leaves revealed a series of defects, all relatedto an irregular differentiation of vascular elements. In addition,in situ hybridization of mutant leaves demonstrates an abnormalpattern of expression of Knotted-1, a marker of meristem function.The presence of multiple roots fused together can be interpretedas suppression of the negative control responsible for the differentiationof only one root primordium. Therefore, the data obtained onseedlings of lsn1 point to a relationship between meristem activity,vascular differentiation and auxin polar transport, and mayallow the identification of a gene which is active during embryogenesis.Copyright2000 Annals of Botany Company Auxin, defective seedling, maize, meristem activity, vascular differentiation, Zea mays.