Responses of tropical legumes from the Brazilian Atlantic Rainforest to simulated acid rain

Abstract

We investigated the morphological and anatomical effects of simulated acid rain on leaves of two species native to the Brazilian Atlantic Rainforest: Paubrasilia echinata and Libidibia ferrea var. leiostachya. Saplings were subjected to acid rain in a simulation chamber during 10 days for 15 min daily, using HSO solution pH 3.0 and, in the control, deionized water. At the end of the experiment, fragments from young and expanding leaves were anatomically analyzed. Although L. ferrea var. leiostachya leaves are more hydrophobic, rain droplets remained in contact with them for a longer time, as in the hydrophilic P. echinata leaves, droplets coalesce and rapidly run off. Visual symptomatology consisted in interveinal and marginal necrotic dots. Microscopic damage found included epicuticular wax flaking, turgor loss and epidermal cell shape alteration, hypertrophy of parenchymatous cells, and epidermal and mesophyll cell collapse. Formation of a wound tissue was observed in P. echinata, and it isolated the necrosis to the adaxial leaf surface. Acid rain increased thickness of all leaf tissues except spongy parenchyma in young leaves of L. ferrea var. leiostachya, and such thickness was maintained throughout leaf expansion. To our knowledge, this is the first report of acidity causing increase in leaf tissue thickness. This could represent the beginning of cell hypertrophy, which was seen in visually affected leaf regions. Paubrasilia echinata was more sensitive, showing earlier symptoms, but the anatomical damage in L. ferrea var. leiostachya was more severe, probably due to the higher time of contact with acid solution in this species.

Responses of photosynthesis and antioxidants to simulated acid rain in mulberry seedlings

“…While AR at an optimal pH range could promote seed germination and increase shoot biomass (Hu et al, 2019), the plants turn yellow (Andrade & Silva, 2017), necrosis occurs (Lee & Weber, 1979), and leaves drop off (Polishchuk et al, 2016) when the AR acidity level exceeds the tolerance of plants. Moreover, AR reduces the photosynthetic rate and cell membrane permeability (Polishchuk et al, 2016), destroys chloroplast integrity (Andrade & Silva, 2017), and decreases the chlorophyll content of the plants (Wyrwicka & Skodowska, 2006), further inhibiting plant growth and development (Debnath et al, 2018). The chemical composition and acidity levels of AR vary in different regions of the world.…”

Acid Rain Increases Impact of Rice Blast on Crop Health via Inhibition of Resistance Enzymes

“…Additive, antagonistic or synergistic interactions between acid rain pollution and pathogens on plants have been reported [ 12 ]. Many studies have focused on either the effects of acid rain or P. oryzae on plants [ 13 , 14 , 15 ], but the interactive effects of acid rain and P. oryzae on rice are still not clear [ 16 ]. Acid rain pollution could have effects on plant diseases by altering physiological metabolism and/or disease resistance systems of the host [ 17 , 18 ].…”

Does Acid Rain Alter the Leaf Anatomy and Photosynthetic Pigments in Urban Trees?

“…Similar anatomical damage from simulated acid rain has been reported in G. americana [31], G. integrifolia, M. artemisiana and S. dulcis [38], Eugenia uniflora (Myrtaceae), and Clusia hilariana (Clusiaceae) [41] Paubrasilia echinata (Fabaceae) and Libidibia ferrea var. Leiostachya (Fabaceae) [42], subjected to pH 3 simulated acid rain treatments.…”

“…These alterations have also been found in G. americana [ 31 ], G. integrifolia , M. artemisiana and S. dulcis [ 38 ], E. uniflora and C. hilariana [ 41 ], P. echinata and L. ferrea var. Leiostachya [ 42 ] and Joannesia princeps (Euphorbiaceae) [ 52 ].…”