Cai Xuan, Wei Hao, Liu Chen, Ren Xiuxia, Thi Luc The, Jeong Byoung Ryong
Institute of Agriculture and Life Science, Gyeongsang National University, Jinju 52828, Korea.
School of Nuclear Technology and Chemistry & Biology, Hubei University of Science and Technology, Xianning 437100, Hubei, China.
Plants (Basel). 2020 Mar 9;9(3):346. doi: 10.3390/plants9030346.
Browning is prevalent in tissue cultures of Pall. (herbaceous peony), and severely affects and restricts the growth and differentiation of the explants. In this study, dipping excised explants in a sodium chloride (NaCl) solution as a pretreatment, adding polyvinyl pyrrolidone (PVP) to the culture medium, storing planted explants at 4 °C for 24 h, and transferring planted explants to a new medium after 24 h were considered as browning-suppression methods in tissue cultures of herbaceous peony 'Festival Maxima'. The treated petal explants were cultured in a culture room with a 16-hour photoperiod, 25 °C temperature, and 80% relative humidity in darkness for 4 to 8 weeks. The results demonstrated that dipping excised explants in a 0.5 g·L NaCl solution, adding 0.5 g·L PVP to the medium, storing planted explants at 4 °C for 24 h, and transferring planted explants to the same fresh medium after 24 h could effectively inhibit browning. Adding PVP to the medium led to the greatest browning suppression percentage of 95%. Storing planted explants at 4 °C for 24 h reduced the effectiveness of other treatments in suppressing browning. After 8 weeks, dipping excised explants in a NaCl solution resulted in the highest callus induction percentage of 75%, while storing explants at 4 °C for 24 h suppressed callus formation. It was observed in all treatments that decreases in browning was accompanied with higher levels of phenols and lower activities of phenylalanine ammonia-lyase (PAL) and polyphenoloxidase (PPO). Overall, the results suggest that dipping in a NaCl solution was effective in alleviating the browning issues of herbaceous peony tissue cultures, and had positive synergistic effects with PVP on browning suppression and callus induction.
褐变在芍药属（草本牡丹）的组织培养中普遍存在，严重影响并限制外植体的生长和分化。在本研究中，将切下的外植体浸泡在氯化钠（NaCl）溶液中作为预处理，在培养基中添加聚乙烯吡咯烷酮（PVP），将种植的外植体在4℃下储存24小时，并在24小时后将种植的外植体转移到新的培养基中，被视为草本牡丹‘Festival Maxima’组织培养中的褐变抑制方法。将处理过的花瓣外植体在光照周期为16小时、温度为25℃、黑暗中相对湿度为80%的培养室中培养4至8周。结果表明，将切下的外植体浸泡在0.5 g·L的NaCl溶液中，向培养基中添加0.5 g·L的PVP，将种植的外植体在4℃下储存24小时，并在24小时后将种植的外植体转移到相同的新鲜培养基中，可以有效抑制褐变。向培养基中添加PVP导致最大褐变抑制率达到95%。将种植的外植体在4℃下储存24小时降低了其他处理抑制褐变的效果。8周后，将切下的外植体浸泡在NaCl溶液中导致最高的愈伤组织诱导率达到75%，而将外植体在4℃下储存24小时则抑制了愈伤组织的形成。在所有处理中都观察到，褐变的减少伴随着酚类物质含量的增加以及苯丙氨酸解氨酶（PAL）和多酚氧化酶（PPO）活性的降低。总体而言，结果表明浸泡在NaCl溶液中可有效缓解草本牡丹组织培养中的褐变问题，并且在抑制褐变和愈伤组织诱导方面与PVP具有积极的协同作用。
