Bergenia crassifolia (L.) Fritsch, a species in the Bergenia genus belongs to the family Saxifragaceae, the order Rosales. For more than 100 years the plant has been known in Asia as a valuable raw material, a source of tannins and pigments. Apart from that, Bergenia crassifolia has been used as a medicinal and ornamental plant. Due to its rich and varied chemical composition (arbutin, tannins, bergenin) the species continues to be the object of pharmaceutical and pharmacological studies.
In the light of research confirming the usefulness of this plant as a source of chemical compounds, it has become increasingly obvious that plant tissue culture should be employed to provide ‘a method of rapid multiplication of Bergenia crassifolia as an alternative to propagation from seeds. The second part of this chapter deals with arbutin determination in regenerated plants. The observations are based on the results of the experiments carried out by the authors.
Systematics and Distribution of Bergenia Plants
The genus Bergenia Moench (Meth. pi. 1794) which is also known in the literature under the synonymous Geryonia Schrank, Megarea Haw., Eropheron Tausch., Piarophylla Raf. and Saxifraga L. is said to consist of 11 species although the Index Kewensis (1895-1974) lists 19 species and Engler 8 species. According to Yeo the genus Bergenia was named in memory of Carl August von Bergen, author of Flora Francofurtana.
Bergenia crassifolia (L.) Fritsch is also known by the following names:
– Bergenia bifolia Moench.,
– Bergenia cordifolia (Haw.) A.Br.,
– Bergenia media (Haw.) Engl.,
– Bergenia orbicularis Stein,
– Bergenia sibirica Hort.,
– Bergenia aemula Tausch.,
– Saxifraga crassifolia L.,
– Saxifraga aemula Tausch.,
– Saxifraga cordifolia Haw.,
– Saxifraga cuneifolia Hort., non L.,
– Saxifraga orbicularis Stein,
– Saxifraga sibirica Hort., non L.,
– Saxifraga macrophylla Clement. Marot,
– Megasea crassifolia Haw.,
– Megasea cordifolia Haw.,
– Megasea media Haw.,
– Megasea orbicularis Hort.,
– Geryonia crassifolia Schrank,
– Geryonia cordifolia Schrank,
– Piarophylla cordifolia Rafin.,
– Piarophylla elliptica Rafin.
The detailed systematics of the genus Bergenia was compiled by Borissowa. She described 11 species, their various names, morphology, distribution, and economic uses. Yeo offered a revision of the genus Bergenia and gave the key to the determination of only six Bergenia species and eight hybrids. The systematic of the Bergenia species is outlined in Table “Classification of Bergenia species”. Apart from the three series presented in Table 1, there are many hybrids cultivated in botanic gardens. A mixed series of hybrids, obtained from crossing many species, was introduced in 1895 under the name Bergenia hybrida by Georg Arends of Wuppertal-Ronsdorf, Germany.
Bergenia is a typical East-Asian genus distributed in two regions, one to the north of and one to the south of the Central Asian Plateau. The series Crassifoliae, to which Bergenia crassifolia belongs, is confined to the northern region of the Central Asian Plateau, which is divided into three separate parts; the area extending from the Tomsk region to Transbaikal; the mountains of the Maritime Territory; and the mountains of North Korea. The plant is widely distributed throughout the USSR and has many garden forms. In its natural condition it grows even at an altitude of 2500 m. In many European countries it is cultivated as an ornamental plant, especially in rock gardens. Bergenia is a perennial herb; the leaves of most species last two seasons. The leaves aciliate petiolar sheath does not form a ligule and is 15-30 cm thick, with shining, broadly elliptic-obovate, petiole sheathing at the base. The flowering stems are up to 30 cm long, and are leafless, with numerous hanging flowers in a rather dense panicle. The flowers in each inflorescence are opened over a long period; a few usually appear before the elongation of the scape. Seeds take about 2 months from the time of pollination to ripen. The creeping rhizomes are ca. 2 cm in diameter. Webb mentions only one species, Bergenia crassifolia, stressing the fact that Bergenia is like Saxifraga in floral structure, but of different habit. In the USSR, the common name of Bergenia is badan ().
Conventional Propagation and Importance
Bergenia plants are propagated by seeds or by rhizome cuttings. Propagations by seeds is time- and labor-consuming, as this species has a slow rate of natural propagation. The plants developed from seeds can be transferred from the pot to the field in the second year after sowing. The leaves can be gathered starting from the second or third year of plant cultivation in the field. The leaves are gathered in autumn, when the arbutin content is at its highest, and should be dried indoors. Raw material dried in the open air has a lower arbutin content and turns brown. The yield of dried leaves from a several years plantation in the USSR is 3-4 t/ha.
In folk medicine, the Bergenia plants have been used to prepare bacteriostatic and anti-inflammatory drugs. Traditional Chinese medicine claims to effectively treat coughs and other respiratory disorders with B. sibirica (= B. crassifolia). The major antitussive constituent is bergenin. In some parts of the USSR the dry leaves of the second year are used for making a beverage, named “Siberian tea“. The rhizomes of B. crassifolia and B. pacifica have been used for years in Siberian tanneries. Some fractions of tannins are used for dying cotton and woolen fabrics green and black. Borissowa in her review of industrial uses of Bergenia plants concentrated on the importance of these plants as a source of tannins and arbutin.
Bergenia crassifolia: Conclusions and Prospectives
The application of in vitro culture for the propagation of Bergenia crassifolia is useful and promising. This method can help to solve two problems, as it permits (1) a high propagation rate of plants, ca. 5000 plantlets from one seedling via callus, in the period of 6 months; and (2) a shorter period necessary for plant development. Plant regeneration from the callus and directly within rhizome cuttings is faster than the development of the plants from seeds. These conclusions were based on the following results:
1. Bergenia crassifolia can be propagated in vitro through adventitious shoots from the intermediate callus or directly via rhizome cuttings.
2. Hypocotyl is the best source of callus.
3. Murashige and Skoog medium supplemented with 1 mg/1 BAP, 0.3 mg/1 NAA and 80 mg/1 AS is suitable for callus induction.
4. Murashige Lily Multiplication Medium (Gibco Bio-Culture) supplemented with 3 mg/1 BAP, 0.1 mg/1 NAA (also containing 80 mg/1 AS) is the best for adventitious shoot development.
5. Nitsch and Nitsch medium (1969) supplemented with 0.5 mg/1 IB A, 0.1 mg/1 kinetin, 10 mg/1 adenine sulphate (AS) and 40 g/1 sucrose is suitable for rooting of the shoots.
Studies on the micropropagation of B. crassifolia plants seem to confirm, that the arbutin content in plants propagated in vitro is within the same range as in plants propagated by conventional methods.
The research done so far has demonstrated the presence of bergenin in B. crassifolia. If future toxicological tests confirm its application in medicine, Bergenia will become an important raw material. In the near future, Bergenia leaves could possibly replace other raw material containing arbutin and tannin, which are scarce and therefore in great demand.
Selections from the book: “Medicinal and Aromatic Plants IV”, 1993.