Anthracnose in açaí palm leaves reduces leaf gas exchange and chlorophyll a fluorescence

Abstract

Leaf spots caused by Colletotrichum sp. decrease photosynthesis rate and hamper the growth of açaí seedlings in nurseries. The objective of the study was to quantify the changes in the photosynthetic performance of açaí leaves inoculated with Colletotrichum sp. through measurements of gas exchange, chlorophyll a fluorescence, and photosynthetic pigments. The rate of net CO 2 assimilation, stomatal conductance, transpiration rate, chlorophyll a and b, ratio of chlorophyll a/b and total chlorophyll decreased, but the intercellular CO 2 concentration increased in inoculated plants compared with non-inoculated plants. Changes in chlorophyll a fluorescence began at 3 days after inoculation (dai) and increased with the number of injuries. The maximum photochemical efficiency ratio (F v /F m) declined sharply as well as other characteristics of chlorophyll a fluorescence, such as the photochemical quenching coefficient, effective quantum yield of PSII, quantum yield of non-regulated energy dissipation, and electron transfer rate. Infection by Colletotrichum sp. reduces the photosynthetic performance due to reduced light capture and assimilation of CO 2 in the mesophyll. Gas exchange and chlorophyll a fluorescence can describe reductions in photosynthetic capacity caused by anthracnose in leaves.

Coffee genotypes morphophysiological adaptation under coffee leaf rust biotic stress

“…(2019) affirms that the dynamic control of stomatal opening is one of the characteristics that provide greater resilience to plants subjected to variable environments. In addition, the stomatal profile depends on genetic and environmental factors (Galon et al, 2013), which may influence the entry and maintenance of pathogens after penetration (Castro et al, 2017;Jiang et al, 2016). Thus, the diameter of xylem vessels and stomatal conductance may be important characteristics in genetic divergence in order to select rust resistant genotypes that have the capacity to reestablish after the stress caused by the Hemileia vastatrix.…”

“…Density and stomatal length are related to the development and sporulation of mildew (Peronospora belbahrii) in Ocimum spp (Homa et al, 2016). The net photosynthetic rate, leaf transpiration and stomatal conductance were negatively correlated with the number of anthracnose lesions in açaí plants (Castro et al, 2017). The study of preformed anatomical structures, as well as the physiological characteristics, is important for a better understanding of the mechanisms involved in resistance to pathogens (Mahajan;Dhillon;Brardwaj, 2017).…”

Modification of anthracnose severity in açaí seedlings by the endophytic fungus Hypoxylon anthochroum strain 2.4996

“…açaí seeds with sodium hypochlorite solution (Castro et al, 2017), they were sown in 250 mL plastic cups with expanded vermiculite (Refratil). After 100 days, the seedlings were transplanted to 2 L plastic bags containing a sterile substrate composed of 50% soil (argisol), 25% cow manure and 25% sawdust.…”

Potential of fungicides, botanicals and biocontrol agents to induce physio-biochemical tolerance on Curcuma longa impaired by Colletotrichum gloeosporioides

“…Improved physio-biochemical functioning of plants is proportionally related to treatments. A major threat of physio-biochemical process is C. gloeosporioides that reduces the tolerance level in plants (Castro et al 2016). The localized infection in plant tissue upregulates defense genes to PR-proteins (salicyclic acid), enzymes (Chitinases and β1,3-glucannases) and transcription factors (expression of genes by interacting with cis-elements present in the promoter region), which are known to activate physio-biochemical tolerance in plants against pathogen (Koch et al 2016; Israel Pagan and Fernando 2018; Ethan et al 2018).…”