The apoplastic oxidative burst as a key factor of hyperhydricity in garlic plantlet in vitro
The phenomenon of hyperhydricity, a physiological disorder occurring frequently in tissue culture, causes ultrastructural modification and metabolic alteration of shoots. Reactive oxygen species (ROS) accumulation and oxidative stress induction are common features during the development of hyperhydricity, but the relationship between organelle redox homeostasis and hyperhydricity with ultrastructural abnormalities is unclear. To investigate the origin of oxidative stress-induced hyperhydricity, changes in oxygen metabolism in different subcellular compartments of garlic plantlets in vitro were studied. Under exogenous hydrogen peroxide (H2O2) stress, the chloroplastic and mitochondrial ultrastructure was disrupted, which was concomitant with aggravated frequency and severity of hyperhydricity. The addition of H2O2 to the growth medium enhanced superoxide anion generation and H2O2 content in the subcellular compartments. Accumulation of ROS was the highest in apoplasts. Compared with control shoots, in apoplasts exogenous H2O2 stimulated a sharp increase in superoxide dismutase activity within 4 days and a sharp increase in ascorbate peroxidase and glutathione reductase activities and in ascorbic acid and glutathione contents after 8 days of H2O2 treatment. In the other subcellular compartments, dramatic improvement of the antioxidant system occurred after 12 days. Thus, the apoplast was the most sensitive compartment among those investigated. Apoplastic ROS might play a signaling role to participate in the coordination of stress adaptation. The apoplastic oxidative burst in garlic plantlets in vitro is an early response to the development of hyperhydricity.
KeywordsGarlic Plantlet in vitro Reactive oxygen species Subcellular compartments Hyperhydricity
Bovine serum albumin
Ethylene diamine tetraacetic acid
Ethylene glycol tetraacetic acid
Infiltrated washing fluid
β-Nicotinamide adenine dinucleotide 2′-phosphate reduced tetrasodium salt
Nitro blue tetrazolium
Potential of hydrogen
Reactive oxygen species
This work was supported by National Natural Science Foundation of China (31372056) and Doctoral Fund of Ministry of Education of China (200803071012).
- Bhattacharjee S (2005) Reactive oxygen species and oxidative burst: roles in stress, senescence and signal transduction in plants. Curr Sci India 89:1113–1121Google Scholar
- Kangasjärvi S, Kangasjärvi J (2014) Towards understanding extracellular ROS sensory and signaling systems in plants. Adv Bot 2014Google Scholar
- Rojas-Martinez L, Visser RG, de Klerk GJ (2010) The hyperhydricity syndrome: waterlogging of plant tissues as a major cause. Propag Ornam Plants 10:169–175Google Scholar
- Wrzaczek M, Brosché M, Salojärvi J, Kangasjärvi S, Idänheimo N, Mersmann S, Robatzek S, Karpiński S, Karpińska B, Kangasjärvi J (2010) Transcriptional regulation of the CRK/DUF26 group of receptor-like protein kinases by ozone and plant hormones in Arabidopsis. BMC Plant Biol 10:95PubMedCentralPubMedCrossRefGoogle Scholar