- Crown gall infected and healthy Kalanchoe pinnata (Lam.)
Persoon plants were analyzed for soluble amino acids. Specifically
the amino acids in young leaf, mature leaf, stem, root, and gall
tissues were quantitatively measured. The plants were inoculated
with the bacterium, Agrobacterium tumefaciens (Smith and Townsend)
Conn., on one side of the stem to initiate unilaterial galls (UG) and
on opposite sides of the stem to produce opposite galls (OG). Plants
with opposite galls and unilateral galls were supplied with either low
or high nitrogen levels in the root medium.
Diseased plants supplied with low nitrogen had larger amino
acid totals in diseased young leaf and stem tissue, and a lower total
in old leaf tissue than controls. There were no qualitative amino
acid patterns common among the different tissues of diseased plants
characteristic for the crown gall disease. When OG and UG plants were compared, the OG plants had more alanine in young leaves,
stems, and roots, but less alanine in old leaves. The major factor
influencing the amino acid pools in the plant tissues appeared to be
the low nitrogen level rather than the presence or position of the
galls on the stem.
The high nitrogen OG plants had about half the amino acid
total found in controls or UG plants. They had lower totals in young
leaves, old leaves, and stems than control tissues; and lower totals
in young leaves, old leaves, and galls than UG plants. The UG
plants had lower totals in young leaves, stems and roots, but a
higher total in old leaves than control tissues.
The OG plants had less aspartic acid, glutamic acid, glutamine,
and arginine in young leaves, old leaves, and galls than UG
plants. Stem tissue from OG plants had less aspartic acid and
glutamic acid. Galls from OG plants had less aspartic acid, glutamic
acid, alanine, glutamine, arginine, serine, and leucines than
galls from UG plants.
No notable amino acid trends were common among tissues of
diseased plants (OG and UG) supplied with high nitrogen. The amino
acid pool levels in the different tissues of OG and UG plants appeared
to be influenced as much by gall positions as by the physiological
presence of the gall.
Since the gall positions on high nitrogen plants had such an effect on amino acid levels in plant tissues, workers who study
crown gall diseased plants in the future should be cognizant of this
fact when inoculating plants. Biochemical and physiological differences
which may be attributed to differences between diseased and
healthy plants could be due to gall positions on the plant.