Ectopic expression of BnCLE19 in Arabidopsis led to a consumption of root meristems.

(A) Two-week old progeny seedlings from a hemizygous p35S::BnCLE19 parental plant were growing on a vertically culture plate, showing segregation for transgenic seedlings with a dominant short root phenotype and three seedlings being wildtype. Note that root geotropism was not affected in these short root seedlings.

(B) A close-up observation of a p35S::BnCLE19 root with the short root phenotype, showing the formation of root hairs to the root tip.

(C) A whole-mount, 7-day old wildtype root of Arabidopsis observed under Nomarski optics. Note the gradual cell size changes from the root meristem to the elongation zone. No obvious pattern change occurred in the following week in the wildtype.

(D) A primary root from a 7-day old p35S::BnCLE19 Arabidopsis line showing the reduced length of the root meristem. Note the evident cell size increase above the short meristem.

(E) A primary root from a 10-day old p35S::BnCLE19 Arabidopsis line. Note the greatly reduced root meristem and the highly vacuolated cells above the meristem and the xylem elements (indicated by an arrowhead). The QC was still recognisable at this stage.

(F) A primary root from a 2-week old p35S::BnCLE19 seedling showing that the root eristem has disappeared completely. Note that the xylem elements (indicated by an arrowhead) reached the central cell zone. No QC can be found at this stage.

(G) Longitudinal section of a root from a 10-day old p35S::BnCLE19 seedling, showing the enlarged and differentiated cells in the root meristem.