Tg. Lamb et al., MOVEMENT OF PSEUDOMONAS-AUREOFACIENS FROM THE RHIZOSPHERE TO AERIAL PLANT-TISSUE, Canadian journal of microbiology, 42(11), 1996, pp. 1112-1120
Following inoculation onto seeds, the rhizobacterium Pseudomonas aureo
faciens Ps3732RNL11 (L11), which contains the constitutively expressed
lacZ and lacY genes from Escherichia coli, was recovered from the int
erior of aerial tissues of all 16 monocot and dicot plants tested, and
the exterior of aerial surfaces of 15. In more detailed studies with
corn, wheat, and broccoli, both Ps3732RNL11 and its nonengineered pare
nt strain PS3732RN (RN) rapidly established large populations on all r
oot systems and smaller densities within the aerial tissues, all of wh
ich persisted at stable levels throughout 12- to 23-day test periods.
There were no differences in the behavior of L11 and RN on any of the
three plant species. L11 invaded the aeriel tissues of corn in at leas
t two distinct ways. First, it moved into the interior of leaves follo
wing inoculation of guttation drops, suggesting that the bacteria may
contaminate the developing shoot prior to its emergence from the soil
and then invade through natural openings. However, when this route was
blocked by inoculating the roots after shoot emergence in either soil
or hydroponic systems, the bacteria still invaded the aerial tissues
within 24 h, suggesting direct vascular transport from the roots. Such
bacterial movement is an important consideration in future field rele
ases of both native and genetically modified rhizobacteria.