## 1 Introduction  
The pre-sowing laser irradiation of seeds has been shown to improve seed germination, seedling and plant growth and development, as well as the quality and quantity of crop yields [1, 2]. Mechanisms such as the activation of phytochrome, phytohormones, and fermentative systems have been proposed to be involved in the laser-induced enhancement effects [3]. A red laser with a wavelength of 632.8 nm, which is produced by the helium-neon (He-Ne) gas laser, has been commonly used for seed irradiation. Factors such as plant species, method of irradiation, dose of irradiation, and the thermal moisture conditions under which the plants were cultivated were reported to affect the impact of the laser stimulation effects, as proposed by [PERSON]'s [3] review and individual reports on various plant species such as pea [4], scorzonera [5, 6], white lupine, and faba bean [7]. _Silybum marianum_ is a medicinal plant that produces silymarin, a compound mixture of flavoolisms and flavonoids predominantly found in the fruits of the plant [8]. Sillymarin has demonstrated hepato-, renal-, and cardio-protective effects, as well as antiviral, neurodegenerative, and cancer preventive effects in in vitro and/or in vivo systems [9], Sillybin A and B are the major components that represent about 50 to 70% of the silymarin composition and have been implicated in the bioactivities of silymarin [10]. Due to the medicinal importance of silymarin, strategies to enhance its production have been actively pursued by various research groups. These include the use of gamma irradiation [11, 12], sodium chloride [11], or biotic elicitors such as methyl jasmonate [13, 14] or fungal extract [11]. [PERSON] and [PERSON] [15] attempted the use of He-Ne lasers in promoting _S. marianum_ seed germination and seedling growth; however, the corresponding study did not proceed further to analyze the effect of lasers on the subsequent plant growth and yield, as well as the silybin A and B production. Chalcone synthase (EC 2.3.1.74) is a group of enzymes that catalyzes the biosynthesis of taxifolin, the flavonoid precursor that forms the flavonoligrans mixture of silymarin. [PERSON] and coworkers [16] identified and partially cloned three _S. marianum_ chalcone synthase genes (_CHS1_, _CHS2_, and _CHS3_) and found that they were differentially expressed in various organs of the plants during the early and late flowering stages. [PERSON] et al. [12] reported that these _CHS_ genes were differentially activated by salinity and gamma radiation, and a strong association was observed between the genes' activation profiles and the silymarin contents in the fruit samples. _CHS1_ and _CHS3_ had the highest transcript levels in petals during the early and mid-flowering stages of _S. marianum_; therefore, they are likely to be involved in anthocyanin and silymarin biosynthesis [16; 17]. _Dictyostelium discoideum_ is a slime mold that shares similar cell structure, behavior, and intracellular signaling with mammalian cells. Therefore, it is one of the eight non-mammalian cell models recognized by the National Institute of Health (NIH), USA, to be widely used in various biomedical studies involving human cells-related diseases and processes, including cancer, wound healing, development, and immune cell response [18]. The _D. discoideum_ cell model offers a great advantage by being an indicator of the potential therapeutic functions of various natural components, including flavonoid compounds such as naringenin and epigallocatechin gallate [19]. Due to the promising biostimulation effects of the He-Ne laser (wavelength 632.8 nm) on various seeds, including that of _S. marianum_, it was thus applied in the present study to further explore its potential in increasing _S. marianum_ plant growth and yield, as well as silybin A and B production. The expressions of genes involved in the biosynthesis of silybin A + B were measured to elucidate the underlying mechanism that contributed to the change in silybin (A + B) contents.