These authors reported that the shoot meristem has been surrounded by leaf primordium
and the serial sections confirmed the unipolar nature of the structures and their connections with the callus tissues indicating that the shoots regeneration occurred through the indirect organogenesis.
Models for the development of leaf polarity support the idea of the homogenous expression of many of these factors in the unpolarized Plastochrone 0 (P0) leaf primordium
, followed by the unequal distribution of abaxial vs.
The venation patterns of higher dicots form in 3-5 different stages during leaf growth and morphogenesis: 1) The bundle of preexisting midvein vasculature grows from the lower stem towards leaf primordium
in an acropetal fashion (from lower to higher regions of the stem); 2) The bundle of pre-existing secondary vasculature continues to the edge during leaf blade formation; 3) Networks of quaternary and higher order veins, including veins at the free ends, form during leaf growth.
Gradual Shifts in Sites of Free Auxin Production during Leaf Primordium
Development and their Role in Vascular Differentiation and Leaf Morphogenesis in Arabidopsis.
Each pair of stipules protects a leaf primordium
, and an innermost pair of stipules, which in turn protects a second leaf primordium
and another pair of stipules; this is successively repeated (Fig.
The small-celled transition zone above the leaf primordium
produces the leaf gap (Fig.
A zonal pattern characteristic of mature vegetative shoot apices becomes evident in the axillary bud during the initiation of the first leaf primordium
During initiation of the vegetative primordia, apex length was measured as the distance from the base of the last initiated leaf primordium
to the tip of the apex dome.
Indeed, Sims and Pearcy (1991) found that Alocasia macrorrhiza grown in the shade did not completely acclimate to increased irradiance until the second leaf primordium
PIN1 localization at the SAM periphery allows auxin to accumulate and to promote leaf primordium
Panicle initiation is largely a process of differentiation, while leaf-tip appearance is largely a process of expansion, and studies with millet and sorghum have shown that PI (and leaf primordium
initiation) is not as sensitive to high temperature episodes and vapor pressure deficit as leaf expansion (Ong, 1983; Hamdi et al.
Development of these varieties differs in size and shape of leaf primordium
at initiation, in the timing of leaf incision, and in growth rate.