Control of browning in plant tissue culture: A review

Abstract

Browning is one of the severe problems in plant tissue culture that hampers successful in vitro propagation of plants especially woody and perennial plants. In order to control the browning problem, different efforts has been made in vitro such as presoaking of explants in antioxidant solution, incorporation of antioxidants into medium, culturing in the dark period and frequent subculturing of explants. Presoaking of explants in antioxidant solutions like polyvinylpyrolidone (PvP) and ascorbic acid (AC) is one of the most frequently used. Incorporation of antioxidants such as 0.2-0.5g/l PvP and 15-250mg/l ascorbic acid into MS medium is commonly used to control browning in different plants and explants followed by activated charcoal, citric acid, MES and AIP. Moreover, frequent sub culturing and incubation of explants in the dark period is the other alternative. This review article includes the study of previous and current research achievements in a comprehensive way on the different methods to control browning problem in plant tissue culture and suggests further optimization for successful control of browning when using the same or different crops as well explants.

Seasonal variation in contamination and browning of Acacia nilotica nodal explants in vitro

“…After surface sterilization, they were washed with distilled water containing 50 mg/l each of citric and ascorbic acids plus 500 mg/l PVP. Soaking explants in antioxidant solution prior to sterilization or treating the explants with antioxidant solution has been reported to be helpful in reducing their browning (Chai et al, 2018;Irshad et al, 2018;Amente and Chimdessa, 2021). This explant collection and sterilization method checked the browning to some extent (Babaei et al, 2013).…”

Managing Lethal Browning and Microbial Contamination in Musa spp. Tissue Culture: Synthesis and Perspectives

“…Ascorbic acid contains ascorbate, which inhibits PPO directly [72]. Furthermore, AA transforms colorless o-quinones produced by PPO action back to diphenols, preventing browning [73]. According to Titvo et al [70], AA scavenges oxygen radicals to prevent phenolic component oxidation in injured tissues, minimizing tissue browning.…”

“…The addition of 15 mL/mL ascorbic acid to the Murashige and Skoog (MS) culture medium effectively prevented oxidation in Musa spp. banana tree explants [73]. Moreover, Nathan et al [74] added cysteine to the growth medium, which significantly reduced the explant browning in banana tissue culture.…”

“…Tissues produced in the dark, for example, frequently exhibit lower levels of browning than those grown in the light [87,88]. The most acceptable medium for shoot regeneration was MS media supplemented with 1.6 mg/L IAA and 4.0 mg/L BAP without ascorbic acid and activated charcoal under darkness for 4 weeks [73,89]. Keeping the cultures completely in the dark for a week can also help reduce browning by blocking or lowering the activity of enzymes involved in both phenol production and oxidation [74,86].…”

“…Increasing the sub-culture frequency has the potential to cause contamination by rhizosphere microbes, making it less effective. Likewise, storing explants in the dark period can only be performed at shoot initiation [73], while for other phases of micropropagation, this is not possible. The combination of using anti-browning compounds in prepared explants with the addition of these compounds to the media may inhibit browning in explants much more effectively in each culture phase by adding to the treatment of storing explants in the dark period during the shoot initiation stage [21,84].…”