Does an antagonistic relationship between ABA and ethylene mediate shoot growth when tomato (Lycopersicon esculentum Mill.) plants encounter compacted soil?

Abstract

Figure 2. Time courses of (a) stomatal conductance and (b) leaf water potential for three genotypes of tomato, Ailsa Craig, ACO1 AS and notabilis. Plants were grown in a split-pot system in which both compartments contained either uncompacted (1·1 g cm -3 ) or compacted soil (1·5 g cm -3 ). A 1·1/1·5 g cm -3 split-pot treatment was also used. Both compartments of the 1·1/1·5 g cm -3 split-pot treatment were either supplied with water (Split-pot); alternatively, a solution containing 100 nm ABA was applied to the 1·5 g cm -3 compartment and water to the 1·1 g cm -3 compartment (Split + ABA). Double standard errors of the mean are shown.

Genetic Dissection of Hormonal Responses in the Roots of Arabidopsis Grown under Continuous Mechanical Impedance

“…It is generally assumed that increased ethylene evolution in mechanically impeded roots is the primary factor in regulating root morphology and development (Goeschl et al, 1966;Kays et al, 1974;Sarquis et al, 1991Sarquis et al, , 1992He et al, 1996). However, a controversy exists on this issue because several studies failed to detect any change in ethylene evolution or 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase activities during root mechanical impedance (Lachno et al, 1982;Moss et al, 1988;Hussain et al, 1999Hussain et al, , 2000. These results raise a debate as to whether ethylene synthesis or ethylene response is the major factor in regulating the growth and morphology during mechanical impedance.…”

Interaction with ethylene: changing views on the role of abscisic acid in root and shoot growth responses to water stress

“…Leaf growth of plants growing in compacted soil was more inhibited in Az34 than in the wild type, and the evidence suggested that changes in leaf water relations were not the cause. Recent studies from the same group demonstrated that ethylene was a major cause of the inhibition of shoot growth in tomato plants grown with their root system divided between pots of uncompacted and compacted soil (Hussain et al 1999(Hussain et al , 2000. As shown in Fig.…”

“…In addition, Hussain et al (2000) attempted to use the ABA-deficient not mutant to demonstrate that the increase in endogenous ABA in the wild type helped to maintain leaf growth during compaction by limiting the production of ethylene. However, ethylene production was similar and inhibition of shoot growth was actually less in the mutant than in the wild type in compacted relative to noncompacted plants.…”

ABA, ethylene and the control of shoot and root growth under water stress

“…Also, by using ethylenedeficient transgenic plants, it was demonstrated that excess ethylene production was a major cause of shoot growth inhibition in wild-type tomato plants (Hussain et al, 1999). Further, treatment with supplemental ABA (applied to the soil) partly reduced shoot ethylene production and partly restored shoot growth in the wildtype plants (Hussain et al, 2000). Thus, as in the waterstressed maize seedlings described above, the normal levels of ABA in the plants subjected to soil compaction appeared to be insufficient to prevent excess ethylene production in the shoot.…”