Abstract
Earlier studies have shown that Stanleya pinnata benefits from selenium hyperaccumulation through ecological benefits and enhanced growth. However, no investigation has assayed the effects of Se hyperaccumulation on plant fitness in the field. This research aimed to analyze how variation in Se accumulation affects S. pinnata fitness, judged from physiological and biochemical performance parameters and herbivory while growing naturally on two seleniferous sites. Natural variation in Se concentration in vegetative and reproductive tissues was determined, and correlations were explored between Se levels with fitness parameters, herbivory damage, and plant defense compounds. Leaf Se concentration varied between 13- and 55-fold in the two populations, averaging 868 and 2482 mg kg−1 dry weight (DW). Furthermore, 83% and 31% of plants from the two populations showed Se hyperaccumulator levels in leaves (>1000 mg kg−1 DW). In seeds, the Se levels varied 3–4-fold and averaged 3372 and 2267 mg kg−1 DW, well above the hyperaccumulator threshold. Plant size and reproductive parameters were not correlated with Se concentration. There was significant herbivory pressure even on the highest-Se plants, likely from Se-resistant herbivores. We conclude that the variation in Se hyperaccumulation did not appear to enhance or compromise S. pinnata fitness in seleniferous habitats within the observed Se range.
Highlights
Selenium (Se) is recognized as an indispensable nutrient for many animals, prokaryotes, and microalgae [1], functioning as a structural component of selenoproteins
Plant size and reproductive parameters were not correlated with Se concentration
The leaf Se concentration was higher in the Pine Ridge plants, which showed an average leaf Se concentration of 2482 mg kg−1 dry weight (DW), while the Coyote Ridge plants showed an average of 868 mg kg−1 DW
Summary
Selenium (Se) is recognized as an indispensable nutrient for many animals, prokaryotes, and microalgae [1], functioning as a structural component of selenoproteins. Selenium can induce the cellular antioxidant system at low levels [3], with a variety of advantageous responses, such as enhanced growth, more efficient photosynthesis, higher accumulation of starch and sugars, delayed senescence, and protection against oxidative stress [3–5]. For instance, experience toxicity above 100 μg g−1 DW (dry weight) and are defined as Se-non accumulators. Plants likely lost their Se-specific metabolism during evolution, since no molecular mechanisms have been discovered that insert seleno-amino acids into proteins [6,7]. Inorganic Se can cause oxidative stress at higher tissue concentrations in most species [10]
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