Leaf characteristics
Leaf traits vary along the leaf economic spectrum from costly leaves
with long lifespan and high leaf mass per area (LMA) to quick-return,
short-lived leaves with high photosynthetic rates and nitrogen content
(Wright et al. 2004).
Species that invest in quick-return leaves are relatively more
susceptible to pathogen attack
(Welsh et al. 2016).
However, quick-return leaves may also have faster leaf expansion rate
than well defended slow-return leaves, which has been associated with
lower pathogen damage, indicating a possible trade-off
(Marquis et al.2001). Plant species that minimize potential points of entry for
pathogens such as stomata number, invest in leaf defense traits that
protect against pathogens ( e.g., thickened cuticle and higher trichome
density) and hold water to a minimum (e.g., hydrophobic leaves with low
surface moisture) are less susceptible to pathogen attack
(Bradley et
al. 2003; Chattopadhyay et al. 2011; Serrano et al.2014). Data on leaf traits and pathogen susceptibility have focused
specifically on a few species and it is not clear to what extent they
are applicable to a wider variety of species, including natives versus
non-natives.
Fungal endophytes have also been shown to provide protection against
pathogens (Dini-Andreote
2020). For example, the mutualism between temperate grasses and fungal
endophytes such as Epichloƫ spp. can defend against pathogens, however
more research on host-endophyte-pathogens interaction is needed in the
context of invasions
(Clay & Schardl 2002;
Schardl et al. 2004). For example, we lack biogeographic home
and away comparisons between populations for the presence and functional
ecology of endophytes. We also lack an understanding of to what extent
endophytes of non-native species contribute to competition with native
plants through increased pathogen resistance and tolerance of their
hosts.