Abscisic Acid Deficiency Causes Changes in Cuticle Permeability and Pectin Composition That Influence Tomato Resistance to Botrytis  cinerea        

Abstract

A mutant of tomato (Solanum lycopersicum) with reduced abscisic acid (ABA) production (sitiens) exhibits increased resistance to the necrotrophic fungus Botrytis cinerea. This resistance is correlated with a rapid and strong hydrogen peroxide-driven cell wall fortification response in epidermis cells that is absent in tomato with normal ABA production. Moreover, basal expression of defense genes is higher in the mutant compared with the wild-type tomato. Given the importance of this fast response in sitiens resistance, we investigated cell wall and cuticle properties of the mutant at the chemical, histological, and ultrastructural levels. We demonstrate that ABA deficiency in the mutant leads to increased cuticle permeability, which is positively correlated with disease resistance. Furthermore, perturbation of ABA levels affects pectin composition. sitiens plants have a relatively higher degree of pectin methylesterification and release different oligosaccharides upon inoculation with B. cinerea. These results show that endogenous plant ABA levels affect the composition of the tomato cuticle and cell wall and demonstrate the importance of cuticle and cell wall chemistry in shaping the outcome of this plant-fungus interaction.

A Hydraulic Model Is Compatible with Rapid Changes in Leaf Elongation under Fluctuating Evaporative Demand and Soil Water Status

“…The fact that lines displaying different ABA biosynthesis rates differed in time courses (i.e. shorter half-time for lines producing less ABA) is compatible with this view, even though ABA affects many processes, including hydraulic conductivity (Parent et al, 2009), and cell wall properties (Curvers et al, 2010).…”

Demethylesterification of Cell Wall Pectins in Arabidopsis Plays a Role in Seed Germination

“…While we did not address any role of endogenous ABA, this factor has been linked to cell wall composition changes. For example, leaves of the ABA-deficient sitiens mutant of tomato have lower levels of GalUA in their cell walls and are less susceptible to degradation by pectinases than those of the wild-type leaves (Curvers et al, 2010). The authors conclude that the GalUA residues within the cell walls of the sitiens leaf cells, while lower in amount, nonetheless have a higher degree of pectin methylesterification, which in turn renders them more resistant to pectinolysis.…”

Nitrate reductase in detached embryos may serve as a marker of the preharvest tolerance of wheat seeds

“…Table 5 -Effects of cross-combinations of fresh endosperm extracts of PHS-tolerant and sensitive on NR-induction in their detached embryos in after 12 h induction presence of 60 mM Combinations of endosperm extracts and detached embryos in KNO 3 NR activity in detached embryos…”

“…NR activity was determined in vitro according to Savidov et al [18] .The reaction medium contained 50 mM Na-phosphate buffer (pH = 7.7), 5 mM KNO 3 and 10 μM FAD. The reaction was started by the addition of the enzyme (i.e., seed part extract).…”

“…The transient rise in ABA content at approximately mid-development coincides with the establishment of dormancy. However, it also coincides with several other major events in seed development, such as dehydration, solidification of endosperm, testa formation and seed abscission [3,4]. A major step forward in seed dormancy research was https://doi.org/10.26577/2218-7979-2016-9-1-31-37 made with the introduction of ABA-deficient mutants of Arabidopsis, maize, pea and tomato.…”