Cryptic CAM photosynthesis in Joshua tree (Yucca brevifolia, Y. jaegeriana)

August 18, 2025

Joshua trees are long-lived perennial monocots native to the Mojave Desert in North America. Composed of two species, Yucca brevifolia and Y. jaegeriana (Asparagaceae), Joshua trees are imperiled by climate change, with decreases in suitable habitat predicted under future climate change scenarios. Relatively little is understood about the ecophysiology of Joshua trees across their range, including the extent to which populations are locally adapted or phenotypically plastic to environmental stress.
Plants in our common gardens showed evidence of Crassulacean acid metabolism photosynthesis (CAM) in a pilot experiment, despite no prior report of this photosynthetic pathway in these species. We further studied the variation and strength of CAM within a single common garden, measuring seedlings representing populations across the range of the two species.
A combination of physiology and transcriptomic data showed low levels of CAM that varied across populations but were unrelated to home environmental conditions. Gene expression confirmed CAM activity and further suggested differences in carbon and nitrogen metabolism between Y. brevifolia and Y. jaegeriana.
Together the results suggest greater physiological diversity between these species than initially expected, particularly at the seedling stage, with implications for future survival of Joshua trees under a warming climate.

Publication Year	2025
Title	Cryptic CAM photosynthesis in Joshua tree (Yucca brevifolia, Y. jaegeriana)
DOI	10.1111/nph.70437
Authors	Karolina Heyduk, Sara J. Scoles-Sciulla, Bridget Hennessy, Madeline Czymmek, Edward V. McAssey, Chase Kane, G. Young Kim, Ifeoluwa Sogunle, Lulu Heublein, Dhriti Sriram, Bryan MacNeill, Michael T. Hren, Todd C. Esque, Jeremy B. Yoder, Michael R. McKain, Christopher Irwin Smith, Lesley A. DeFalco
Publication Type	Article
Publication Subtype	Journal Article
Series Title	New Phytologist
Index ID	70271913
Record Source	USGS Publications Warehouse
USGS Organization	Western Ecological Research Center

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