Tissue Culture of Haworthia Turgida

Table of Contents

HAWORTHIA: INTRODUCTION

Haworthia turgida, also known by its common name, windowpane plant, belongs to the group of plants known as succulents. It is native to the Western Cape province of South Africa. The common name of the plant comes from its translucent pane of leaves. Haworthia turgida prefers a habitat of rocky limestone or slate cliffs where it can be protected from strong sunlight in the shade of thorn bushes. Other varieties of the plant include Haworthia turgida var. longibracteata and Haworthia turgida var. suberecta.

The plants have grassy green leaves with crystalline textures. These are broad, thick, ovate-lanceolate to long-triangular, and fleshy in appearance. They are generally yellowish-green or green in color. However, in strong light, the leaves turn yellow. They form compact rosettes, 5-10 cm in diameter with 20-40 tightly packed leaves. In the spring season, the rosettes produce single, upright, and wiry stems carrying tiny, tubular, and white flowers.

Haworthia turgida grows in winters and is dormant in the summer or hotter months of the year. They require porous soil with excellent drainage for their growth and watering is only required when soil is dry in touch. However, it's important to never let the plant sit in too much water.

The distinctive feature of the plant and its leaves has created a sparkling interest in the plant from botanists and succulent plant collectors. The plants can be propagated by vegetative means through leaf cuttings, however, this process is slow and a low number of offshoots are produced from each plant. For this reason, micropropagation is considered as an effective alternative technique for the mass multiplication of the plants.

The procedure of culturing Haworthia turgida by tissue culture method is explained below.

Classification

Clade: Angiosperms

Class: Monocots

Order: Asparagales

Family: Asphodelaceae

Sub-family: Asphodeloideae

Genus: Haworthia

Species: H. turgida

Propagation of Haworthia Using Tissue Culture Techniques

Materials Required

Fresh leaves of Haworthia turgida explants, liquid detergent, 70% ethanol, double distilled water, 0.1% HgCl2, 0.05% Tween-20, disinfected filter paper, and sterilized blade.

Preparation of the culture medium:

• Murashige-Skoog basal salts and vitamins as base medium mixed with 3 % (w/v) sucrose and 0.7% (w/v) agar.
• Adjust the pH of the medium to 5.8.
• Autoclave the medium at 121 ℃ for 20 minutes.
• Add plant growth regulators before adjusting the pH of the medium and sterilizing it.

Procedure

Sterilizing the leaf explants:

1. Wash the fresh leaves of Haworthia turgida in tap water mixed with a few drops of liquid detergent for 30 minutes.
2. Decontaminate the leaves with 70% ethanol for 30 seconds.
3. Wash the leaves with two to three changes of sterile water.
4. Sterilize the leaf explants with 0.1% HgCl2 mixed with 0.05% Tween-20 for 5-minutes.
5. Then, wash the explants 3-4 times with sterilized water and dry them using disinfectant filter papers.
6. Remove the injured tissues from the sterilized leaves and cut them into 0.5-1.0 cm pieces.

Callus induction and propagation:

1. Inoculate the leaf explants on the prepared basal MS culture medium with 0.1 mg/L NAA (1-naphthaleneacetic acid) and 1.0 mg/L BA (6-benzyladenine).
2. Place the cultures at 23-25 ℃ under a 14 hour photoperiod in cool-white fluorescent lamps.
3. The callus will develop in a few weeks. Keep observing your cultures.
4. When the callus is generated, cut them into 1-2 cm2 pieces.
5. Transfer the pieces of callus to a fresh medium supplemented with 2.5 mg/L TDZ (thidiazuron), 0.mg/L NAA, and 1.0mg/L BA for callus proliferation.
6. After 30 days, you can observe a full-grown healthy callus.

Adventitious shoot differentiation:

1. Cut the healthy callus into small pieces of 2 cm2.
2. Transfer the callus to the MS medium containing 1.0 mg/L BA and 0.2 mg/L 2,4-D for adventitious shoot induction.

Induction of root formation:

1. When the shoots are grown 2-3 cm, transfer them to the MS medium with 0.05 mg/L NAA.
2. After 30 days, you can observe the root formation.
3. Take out the rooted plants from the culture vessel and wash them in running water to remove the attached agar.
4. Then, transfer the plants to acclimatization boxes (7 x 7 cm) with a mixture of vermiculite and flower nutrient soil. Then, place the plants in the greenhouse under a natural photoperiod condition at 23-27 ℃ and 70% relative humidity.

References

1. Liu, B., Fang, H., Meng, C., Chen, M., Chai, Q., Zhang, K., & Liu, S. (2017). Establishment of a Rapid and Efficient Micropropagation System for Succulent Plant Haworthia turgida Haw. . HortScience, 52(9), 1278–1282. DOI:10.21273/hortsci12056-17
2. Mycock, D. J., Watt, M. P., Hannweg, K. F., Naicker, K., Makwarela, M., & Berjak, P. (1997). Somatic embryogenesis of two indigenous South African Haworthia spp. (H. limifolia and H. koelmaniorum). South African Journal of Botany, 63(6), 345–350. DOI:10.1016/s0254-6299(15)30784-5
3. http://www.llifle.com/Encyclopedia/SUCCULENTS/Family/Aloaceae/16777/Haworthia_turgida
4. http://www.gardenanswers.com/succulents/haworthia-...
5. https://en.wikipedia.org/wiki/Haworthia_turgida