Proteomic profiling and redox status alteration of recalcitrant tea (Camellia sinensis) seed in response to desiccation

Abstract

Tea seed is believed to be recalcitrant based on its sensitivity to chilling or drying stress. Reactive oxygen species (ROS) and alterations in cytosolic redox status have been implicated in intolerance to desiccation by recalcitrant seed, but there is little information available regarding how ROS are regulated in seeds susceptible to drying stress. We investigated changes in protein expression and activity in tea embryo in response to desiccation using physiological and proteomic methods. Results showed that desiccation treatment dramatically induced the accumulation of H(2)O(2) in tea embryos, accompanied by increased activities of antioxidant enzymes like ascorbate peroxidase (APX) and superoxide dismutase (SOD). Proteomic analyses also demonstrated that 23 proteins associated with defense response, metabolism and redox status were up-regulated following desiccation. Increase in antioxidants, ascorbic acid (AsA) and catalase (CAT) (H(2)O(2) scavengers) partially assuaged desiccation damage to tea seed, resulting in improved germination rates. Higher accumulation of H(2)O(2) aggravated desiccation damage to seeds leading to lower germination activity. We propose that desiccation causes an over-accumulation of ROS that are not efficiently scavenged by increased levels of antioxidant enzymes. High levels of ROS alter the redox status and are detrimental to seed viability. Reducing ROS to appropriate concentrations is an efficient way to reduce desiccation damage and improve germination rates of recalcitrant seeds.

Quantitative proteomics analysis reveals that S-nitrosoglutathione reductase (GSNOR) and nitric oxide signaling enhance poplar defense against chilling stress

“…The homogenates were centrifuged at 12,000g for 15 min at 4°C, and the total soluble protein concentration of supernatants was determined by the Bradford method (Bradford 1976). The activities of MDHAR, DHAR, APX, and GR were determined as described (Chen et al 2011).…”

Changes in Seed Germination Ability, Lipid Peroxidation and Antioxidant Enzyme Activities of Ginkgo biloba Seed during Desiccation

“…This may have been due to loss of the selective permeability of cellular membranes, suggesting that membrane integrity is vital, since any desiccation damage may have immediate consequences for the seeds' germinability. Recent studies have confirmed that decreased viability of recalcitrant seeds was closely related to the accumulation of membrane lipid peroxides, such as in Camellia sinensis [47]; Quercus robur [48]; Trichilia connaroides [49]; and other recalcitrant seeds. Thus, the desiccation of G. biloba seeds accompanied by a deepening degree of membrane lipid oxidation led to the severe damage of the membrane system, causing a large accumulation of MDA.…”

ASCORBATE PEROXIDASE6 Protects Arabidopsis Desiccating and Germinating Seeds from Stress and Mediates Cross Talk between Reactive Oxygen Species, Abscisic Acid, and Auxin

“…Dehydration and rehydration during seed development or during germination are associated with high levels of oxidative stress (Dandoy et al, 1987;Rajjou et al, 2012). Overaccumulation of reactive oxygen species (ROS) can cause oxidative damage to a wide range of cellular components and cause DNA damage, reducing the seed's ability to germinate (Bailly et al, 2008;Chen et al, 2011;Parkhey et al, 2012). An optimal range of ROS levels is required for successful germination (Bailly et al, 2008).…”