Print PageDrought impacts upon ecosystem and crop productivity and with climate change drought is predicted to increase in many parts of the world. One way that plants respond to drought is by changing their liquid and gas phase conductance to water and CO2 through alternation in the function of aquaporins. Though aquaporin physiology is becoming increasingly well understood, few studies have looked at their impact on growth and performance in plants grown in the field under conditions of drought.
Circadian rhythm is known to affect liquid and gas phase conductance in plants. Two parents of Brassica rapa with different circadian periods were crossed, resulting in range of recombinant inbred lines, ten of which were selected for this study. B. rapa is an important crop species, 12 different crop genotypes were also included to incorporate the wide range of ‘natural’ genetic variability in this species. Plants were grown in a field setting and subjected to drought. The relative contribution of aquaporins to flow was assessed using an inhibitor. Whole plant conductance, leaf gas exchange, growth, seed production and mesophyll conductance to CO2 were measured.
Results/Conclusions
There were genotypic differences in the contribution of aquaporins to flow as well as in all of the other traits. Under well-watered conditions genotypes that had a greater contribution of aquaporins to flow had a higher mesophyll conductance, a 100% increase in stomatal conductance and a 50% increase in the maximum rate of photosynthesis. Differences were less pronounced under conditions of drought. Particularly important from a fitness perspective, is that these genotypes also produced almost double the mass of seed. This evidence suggests that aquaporins are an important trait affecting plant performance in a field setting and suggest that predictions of future responses to drought should incorporate potential aquaporin controls on the loss of water and the uptake of carbon.
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