Commercially available seeds of tomato (Solanum lycopersicum
L. cv Jiangshu 14) were surface-sterilized and rinsed extensively in
distilled water. After soaking overnight, seeds were germinated on
filter papers imbibed in distilled water at 25 1 C in the darkness.
2-d-old seedlings were then transferred to an illuminating incubator
and maintained at 25 1 C with a 14-h photoperiod at
200 mmol m2 s1 intensity.
After growing for another day, the selected identical seedlings
with radicals 2e3 mm were incubated with 4 ml of the various
solutions as indicated for the indicated time points. Afterward, the
photographs were taken. The number of lateral root (LR) and the
length of all LRs (>1 mm) per seedling, as well as LR density (the
number of LR per cm primary root; LRs$cm1) were quantified with
Image J software. LR primordia (LRP) per seedling were observed
after 1 d of treatments by root squash preparations and quantified
by a light microscope (model Stemi 2000-C; Carl Zeiss, Germany).
According to the previous method (Correa-Aragunde et al., 2006),
the root apical meristems of tomato seedlings at the indicated time
points were cut off and the shoots were removed by cutting below
the root-shoot junction in order to obtain samples of only lateral
root-inducible segments for the corresponding biochemical and
molecular determination.