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United States Department of Agriculture

Agricultural Research Service

Research Project: GENETIC MECHANISMS AND MOLECULAR GENETIC RESOURCES FOR MAIZE

Location: Plant Genetics Research

Title: The desert moss Pterygoneurum lamellatum (Pottiaceae) exhibits an inducible ecological strategy of desiccation tolerance: effects of rate of drying on shoot damage and regeneration

Authors
item Stark, Lloyd -
item Greenwood, Joshua -
item Brinda, John -
item OLIVER, MELVIN

Submitted to: American Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 8, 2013
Publication Date: August 1, 2013
Repository URL: http://handle.nal.usda.gov/10113/57469
Citation: Stark, L., Greenwood, J., Brinda, J., Oliver, M.J. 2013. The desert moss Pterygoneurum lamellatum (Pottiaceae) exhibits an inducible ecological strategy of desiccation tolerance: effects of rate of drying on shoot damage and regeneration. American Journal of Botany. 100(8):1522-1531.

Interpretive Summary: In understanding how plants tolerate dehydration of their vegetative cells, an important consideration in drought tolerance strategies, it is important to understand how the mechanisms of tolerance are controlled. Mosses are regarded as a group that incorporates a constitutive mechanism of desiccation tolerance, especially terrestrial species. Here we test the hypothesis that the opposing ecological strategy of desiccation tolerance, inducibility, is also present in a desert moss, and addressed by varying rates of drying in a laboratory study. Rate of drying significantly affected all recovery responses, with very rapid drying rates severely damaging the entire shoot except the shoot apex and resulting in slower growth rates, fewer regenerative shoots produced, and a compromised photosynthetic system as inferred from fluorescence parameters. The implications of this are that mosses also utilize an inducible tolerance program based upon the rate of prior drying, thus offering insights into the flexibility of the control of this important trait. In a practical sense this offers us the opportunity to fully delineate the genetic and environmental triggers that allow for the induction of a dehydration tolerance mechanism and by so doing, allow us to explore the possibility of enabling dehydration tolerance of important economic species, such as corn and soybean, which have the appropriate genes but they are dormant in vegetative tissues.

Technical Abstract: Premise of the study: Bryophytes are regarded as a clade incorporating constitutive desiccation tolerance, especially terrestrial species. Here we test the hypothesis that the opposing ecological strategy of desiccation tolerance, inducibility, is present in a desert moss, and addressed by varying rates of drying in a laboratory study. Methods plants were cloned, grown in continuous culture (dehardened) for several months, and subjected to rates of drying ranging from 30 min to 53 h, rehydrated and tested for recovery using chlorophyll fluorescence, leaf damage, and regeneration of protonema and shoots. Key results: Rate of drying significantly affected all recovery responses, with very rapid drying rates severely damaging the entire shoot except the shoot apex and resulting in slower growth rates, fewer regenerative shoots produced, and a compromised photosynthetic system as inferred from fluorescence parameters. Conclusions: For the first time, a desert moss is shown to exhibit an ecological strategy of desiccation tolerance that is inducible based upon the rate of prior drying, thus challenging the assumption that aridland bryophytes rely exclusively on constitutive protection from desiccation. A technique is presented that allows a separation of rate of drying from equilibrating relative humidity, and which removes site (field) effects and age heterogeneity from shoots. Results indicate that previous considerations defining a slow-dry event in bryophytes need reevaluation, and that the ecological strategy of inducible desiccation tolerance is probably more common than currently understood among terrestrial bryophytes.

Last Modified: 9/10/2014
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