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Fig. 5. Simultaneous loss of both KANADI and YABBY functions. (A) In contrast to
the clear asymmetric development of kan1 kan2 leaves, kan1 kan2
fil yab3 quadruple mutants initiate nearly radial first leaves. The two
genotypes, kan1-2 kan2-1 fil-5 yab3-1 and kan1-2 kan2-1 fil-8
yab3-2, are indistinguishable in morphology. (B) The leaves have
trichomes on all sides, an adaxial characteristic of the first leaves, and
expand laterally only at their distal end. Later-formed leaves are short,
thick and lack organized plane of expansion. (C-E) The epidermal surfaces of
these leaves (E) appear similar on both sides, and resemble those of adaxial
leaf surfaces (C), rather than the abaxial leaf surfaces (D) of wild-type
leaves. (F,K) Flower organs of the quadruple mutants are completely radialized
(F), lack epidermal characteristics of wild-type floral organs, and resemble
the flowers of adaxialized homozygous phb-1d mutants (K). (G)
Longitudinal section through a developing third leaf of a kan1-2 kan2-1
fil-5 yab3-1 quadruple mutant reveals anatomical symmetry. (H,I) This
symmetry is also apparent in by transverse sections of either young leaf
primordia (H) or a differentiating leaf (I). (J) In a similar fashion to its
expression in wild-type leaves, FIL mRNA is detected in the margins
of the quadruple mutant leaf where prolonged cell divisions occurs, yet this
expression is no longer abaxial as seen in this transverse section through two
leaves above the level of the meristem. (L) Leaves of fil-5 yab3-1
show dramatic loss in their polarity as expressed by trichome distribution on
both sides of the first two leaves, when the activity of the KANADI proteins
is partially compromised. This phenotype, is in sharp contrast to the normal
distribution of trichomes in fil-5 yab3-1 alone (inset; first three
leaves removed). (M) Besides the distribution of cell types along the ab/ad
leaf axes, all the described mutations have a strong effect on growth along
the proximal/distal axis. In general, increasing losses of asymmetric
development are accompanied by reduced leaf elongation. All leaves shown,
except for no. 5 are fully expanded 4th or 5th leaves of the respective
genotypes. (1, wild type; 2, kan1 kan2 adaxial surface; 3, kan1
kan2 abaxial surface; 4, fil5 yab3-1; 5, kan1-2 kan2-1 fil-5
yab3-1 first leaf; 6, kan1-2 kan2-1 fil-5 yab3-1 5th leaf; 7,
phb-1d. (Bars to the left of each leaf: 5 mm.) ab, abaxial; ad,
adaxial; lp, leaf primordium; m, meristem; wt, wild type. Scale bars: 100
µm (C-E and G-I).
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