Abstract Detail

Physiology

Fiallo, Samantha [1], Holmlund, Helen [2], Davis, Stephen [3].

Comparative Gas Exchange Activity in the Resurrection Fern, Pentagramma triangularis, During Seasonal Desiccation and Recovery.

Many species of ferns in the Santa Monica Mountains of southern California possess physiological mechanisms that allow them to withstand protracted summer drought. A common species, Pentagramma triangularis (gold back fern), utilizes desiccation tolerance as a drought survival mechanism. We understand few details of this survival mechanism. We chose to examine maximum gas exchange throughout the desiccation process of Pentagramma triangularis, growing in its natural setting, in Newton Canyon of the Santa Monica Mountains, and during the resurrection process in Piuma Canyon following the rains of 2018. We used a field portable gas-exchange system (Li-Cor 6800) to measure maximum photosynthesis under saturating light (Amax), stomatal conductance to water vapor diffusion (g_s), as well as chlorophyll fluorescence parameters in the dark (Fv/Fm) and saturated light (Fv’/Fm’). Before desiccation in Newton Canyon, the average photosynthetic value of the plants was 7 ± 1 μmol m²s^-1 and the average dark-adapted fluorescence value of the plants was 0.80 ± 0.04. The average number of days required for the ferns to fully desiccate was 40 days. After resurrecting, the ferns in Piuma Canyon achieved an average post-recovery photosynthetic rate of 7 ± 2 μmol m²s^-1 and an average post-recovery dark-adapted fluorescence value of 0.82 ± 0.007, matching pre-desiccation values. The average number of days it took for the ferns to fully resurrect after the rains was 20 days. The desiccation process was much slower, because of the gradual drying of bulk soil during dehydration, and less variable than the recovery process. The increase in variability during rehydration can be attributed to differential stipe length that presumably influences the distribution of positive root pressure for embolism reversal. During the resurrection process, these two values increased rapidly during the first few days of rainfall and then remained at a constant value. This rapid recovery is a successful strategy for recovery after prolonged summer drought. Other than levels of photoprotection, recovery of Pentagramma triangularis successfully reached pre-desiccation values. These data suggest the advantage that desiccation tolerant plants have over other drought deciduous ferns that must slowly construct a new frond after seasonal dry events. The resurrection strategy may be increasingly selected for as climate change causes more droughts and sporadic rain events.

1 - Pepperdine University, Natural Science Division, 24255 Pacific Coast Hwy, Malibu, CA, 90263, United States
2 - University of CA, Santa Cruz, Ecology and Evolutionary Biology, 130 McAllister Way, Santa Cruz, CA, 95060, USA
3 - Pepperdine University, NATURAL SCIENCE DIV, 24255 Pacific Coast Highway, Malibu, CA, 90263, United States

Keywords:
Resurrection
Desiccation
fern
drought.

Presentation Type: Poster
Session: P, Physiology Posters
Location: Arizona Ballroom/Starr Pass
Date: Monday, July 29th, 2019
Time: 5:30 PM This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PPS003
Abstract ID:819
Candidate for Awards:Physiological Section Best poster presentation,Physiological Section Physiological Section Li-COR Prize