A Review: The Effect of Plant Growth Regulators on Micropropagation of Aglaonema sp

Meutia Zahara*1,2, Cho Cho Win3 1 Postgraduate Program of Public Health, Universitas Muhammadiyah Aceh Jl. Muhammadiyah No 91, Batoh, 23245, Banda Aceh, Indonesia 2 Department of Biology, Islamic Faculty, Universitas Muhammadiyah Aceh Jl. Muhammadiyah No 91, Batoh, 23245, Banda Aceh, Indonesia 3 National Project Coordinator, Farming System Sustainability Project Myanmar Nay Pyi Taw, 15011, Myanmar *Corresponding author: teeya_razali@yahoo.co.id; meutia.zahara@unmuha.ac.id


INTRODUCTION
Some ornamental plants in the world have accompanied the historical value, used to use as an expression symbol of wellbeing and the beauty of landscape. As in Asia, Africa and Latin America using ornamental plants for the tradition of brighten ceremonies and national day celebrations, this condition increases the ornamental plants popularity. Currently, the most rapid expanding ornamental plants are foliage plants for indoor use, bedding and garden plants (Mariani et al., 2011). Aglaonema consists of many important and demanding cultivar of foliage plants due to their beautiful shape, colorful, drought tolerance and low relative humidity .
Nowadays, Aglaonema sp. becomes very famous in Indonesia, especially during the pandemic covid-19. Many people tend to stay home to stop the spreading of the virus, one of the activities can be done during stay home is growing the plants as well as ornamental plants. Aglaonema sp. is one of important dan well known foliage ornamental plants in Indonesia, commonly called as "Sri Rezeki" and comprised more than 21 species (Dikayani et al., 2013). This genus also known as Chinese Evergreen, a monocot which is belongs to Araceae family and spreads around southeastern Asia, northeastern India, southern China, Indonesia, Malaysia, and New Guinea (Chen et al., 2003). This foliage ornamental plant has been produced due to its attractive foliage shape, easy to cultivated, low light tolerance and low relative humidity (Henny, 2000;Chen et al., 2002). New cultivars have been released continuously to maintain the popularity of the plants (Chen et al., 2002).
Due to the non-simultaneous flowering and short life cycle of the pollen make the sexual reproduction difficult, so most of Aglaonema sp. have been propagated by cutting the rooting part from nodes or shoot basal division as the basic method (Barakat and Gaber, 2018). Another condition is the problem with endogenous pathogen that may stay in the vascular bundle tissue and may spread through the cutting method (Chase, 1997). Micropropagation is an advanced propagation method through vegetative way to produce large amount of seedling in a short time and pathogen-free transplants. This method starting with growing plantlets on a medium contains water and nutrition under aseptic condition (Chen, 2007;Chen et al., 2013;Chen 2015).

GENERAL INFPORMATION
Aglaonema is a genus from monocots that belongs to Araceae family consists of 21 species that accepted and published (Table 1). These perennial herbs have an erect and decumbent stem which can grow along the ground and may rooting around the nodes. Containing the most beautiful shape and colors of the leaves, it shows very good colors combination, such as green and orange, green and red, green and yellow, green and white, green and pink, etc (Mariani et al., 2011). Most of Aglaonema's species have white roots, 1-5 cm thick stem, can reach until 50 cm in height, the inflorescence type called a spadix (Mariani et al., 2011), the color of the flower mostly white and normally bloom during March-July. Aglaonema also contains come toxic agent named calcium oxalate crystal to protect themselves from the enemy, this agent will cause some irritation on the skin.

MICROPROPAGATION OF Aglaonema sp.
Micropropagation is the tissue culture technique application to propagate plants under aseptic condition. This technique could be done to produce large amount of pathogen-free and uniform transplants in a short time and in a small place (Chen et al., 2013;Chen 2015). Some protocols have been conducted for the micropropagation of Aglaonema sp., but still not meet the purposes with Aglaonema, mainly due to the difficulty to maintain the aseptic culture condition , low rate of shoot multiplication reported by Chen and Yeh (2007) as well as in the research conducted by Zhang et al. (2004), and lack of technical information on micropropagation procedure of Aglaonema (Mariani et al., 2011).
In vitro technique could be done for physiologically uniform of plant production and rapid multiplication. In many micropropagation's research conducted with high number of treatments, using the plant growth regulators (PGRs) and some dosages were tested to obtain a good propagation protocol. Endogenous microbial contamination is the most serious problem in micropropagation of ornamental aroids, including Aglaonema .
The use of PGR combination on the medium for Aglaonema sp. micropropagation was conducted by many researchers for some purposes. Fang et al. (2013) conducted a research with Aglaonema 'Lady valentine' as the popular red cultivar that were cultured on the Murashige and Skoog (MS) medium supplemented with PGRs to develop an efficient micropropagation procedure through adventitious shoot induction and proliferation. The single nodal stem with an axillary bud were cultured on 10 ml MS medium supplemented with 32 mg. l -1 gentamicin, 8 mg. l -1 tetracycline and 4 mg. l -1 chloramphenicol. The best growth of axillary obtained when 10 mg. l -1 of 6-benzyladenine (BA) supplemented to the medium. Afterwards, the single nodal stem produced were cultured on MS medium supplemented with PGR combination; naphthalene acetic acid (NAA) and thidiazuron (TDZ) ( Table 2). The results showed that the average of 10.9 adventitious shoots per stem obtained from the combination of 0.5 mg. l -1 NAA and 2 mg. l -1 TDZ. Later on, small shoots formation was culture on the medium supplemented with BA and GA3. The concentration of 0.5-5 mg. l -1 of BA showed more effective for shoot proliferation and elongation compared to 0.5 mg. l -1 GA3 treatments (Fang et al., 2013). After three months of culture, the longest shoot (2.69 cm) were obtained from 5 mg. l -1 BA. The research conducted with Aglaonema 'White Tip' cultivar showed that each nodal formed six shoots after cultured on MS medium supplemented with 6.8 mg. l -1 BA after 60 days of culture . Direct shoot formation induced on Aglaonema 'White Tip' after the explants cultured on the medium supplemented with 1.1-2.2 mg. l -1 dicamba (3,6-dichloro-2-methoxybenzoic acid) and 2.2 mg. l -1 TDZ . While in Aglaonema commutatum, an average of 4.1 shoots formed every month from the stem which were cultured on the medium supplemented with 2.5 mg. l -1 BA and 0.05-0.1 mg. l -1 NAA (Zhang et al., 2004). Aglaonema var. Lipstick research showed that after 16 weeks of culture formed callus formation by combination treatment of 5 mg. l -1 IAA and 5 mg. l -1 BAP as well as in the combination of 8 mg. l -1 IAA and 5 mg. l -1 BAP, the color of the callus are clear, globular shape and friable textures (Dewi et al., 2012).
Aglaonema widuri or Aglaonema red peacock were micropropagated on MS medium supplemented with three cytokinin (BA, TDZ and 2-ip) with one auxin (NAA) aimed to develop a protocol for high frequency multiplication (Fig.1). The highest shoot proliferation rate obtained in the combination of 3 mg. l -1 BA and 0.2 mg. l -1 NAA (6.00 number of shoots and 7.75 cm in length/explant), the maximum nodes formed by the combination of 4.00 mg. l -1 BA + 0.10 mg. l -1 NAA 0.50 mg. l -1 TDZ (13.25/explant), The largest leaf number formed in the combination of 3.50 mg. l -1 BA and 0.20 mg. l -1 NAA, while the maximum root development obtained from the combination of 3.00 mg. l -1 and 0.20 mg. l -1 NAA. The most suitable plant growth regulators for Aglaonema widuri tissue culture was the combination of 3.50 mg. l -1 BA and 0.20 mg. l -1 NAA (Kaviani et al., 2018).

CONCLUSION
Aglaonema is monocots that's belonging to the Araceae family and consist of around 21 species. The popularity of this genus is attributed by their beautiful shape and color of the leave, easy to grow, low light tolerance and low humidity. The rooting of cutting of basal shoots are the main method of cultivating the Aglaonema sp., this method is high risk of pathogen transfer since the endogenous pathogen as the main problem from this genus. Some micropropagation techniques were conducted to cultivated the Aglaonema sp. in a short time, with a large number of seedlings in a small place and to produce plant-free pathogen, the use of the PGRs combination is one of the methods in micropropagation. Further research needed to complete the protocols of the Aglaonema sp. micropropagation.