Physiological Response of Lavender (Lavandula sp. L.) to Phenylalanine and Crest for Medical Applications

The genus Lavandula is an important member of the family Lamiaceae, consisting of about 30 species and 100 varieties. Lavender is a perennial shrub and an evergreen bushy semi-shrub [1]. The area of origin for the Lavandula species is southern Europe, most specifically the western Mediterranean basin, extending from East to the Dalmatian Coast and Greece [2]. Lavender flowers are used as a medicine. Lavender is also used to treat some skin conditions, such as burns, wounds, minor scratches, and psoriasis. However, lavender essential oils are used to treat anxiety and insomnia [3]. Moreover, Lavandula contain essential oils and phenolic compounds known for their general antioxidant abilities. Scientists have investigated its chemical composition, biological activities, and potential therapeutic uses [4]. In several phytopharmaceuticals, lavender is utilized as a cholagogue, carminative, stomachic, diuretic, and spasmolytic. Essential oils, flavonoids, phenolic acids, anthocyanin, and numerous other valuable phenolic compounds are among the many natural antioxidants found in flowers, which are typically a major part of plants. Lavender's many physiologically active components, primarily essential oils and phenolic and aromatic compounds, are thought to have antioxidant, antifungal, and anti-carcinogenic properties [5,6]. There have been numerous animal and human studies evaluating the medicinal properties of lavender using modern scientific methods. These studies have demonstrated the potential for

reviving lavender's therapeutic efficacy in neurological disorders based on evidence-based medicine [1,7].

The different varieties of this plant range in height from 9 inches to 3 feet. Lavender is divided into four main categories: Among these categories under study is English lavender, known as Lavandula angustifolia, which is a frost-resistant species, characterised by its beautiful varieties and bright flower colors; and Lavandula intermedia, a hybrid between Lavandula latifolia and Lavandula angustifolia. The different types of lavender are similar in their ethnobotanical characteristics and main chemical components [5]. Plants also create a variety of amino acids and proteins that support their defensive systems. Primary and secondary metabolic pathways are the main uses for the amino acid phenylalanine (PA) [8,9]. Additionally, it acts as a precursor for numerous phenolic chemicals that are crucial for plant defence against unfavourable environmental circumstances, including flavonoids, lignin, condensed tannins, benzenoids, and volatile phenylpropanoids [10]. Some research on the growth of soybeans (Glycine max) has demonstrated the benefits of foliar phenylalanine spraying. [11], Salvia officinalis, or common sage [12]. One plant hormone that significantly speeds up plant growth and development is gibberellic acid (GA3). Because GA may regulate a range of growth and development phenomena in different crops, it is regarded as a plant growth regulator. GA3 enhances dry weight and yield [14], stimulates stem elongation, and encourages plant growth [15,16]. Lavender productivity can be greatly impacted by growing site, climate, propagation technique, and morphological traits. [17]. Additionally, the efficient production of lavender is facilitated by the use of environmentally friendly and adaptable growing techniques, such as plant growth regulators (PGRs), which enhance the genetic potential of plants. According to Wilkinson et al. [18] and Lymperopoulos et al. [9], the application of PGRs can boost yields and enhance the quality of farmed goods. Additionally, PGR treatment improves photosynthesis, respiration, and nutrition by boosting cell activity in the plant body through biochemical processes. [12]. Because of their therapeutic and medical use, medicinal plants have contributed to the global economic cycle and are now widely consumed, especially in wealthy nations [7]. Additionally, because they can adapt to soil and climate conditions, herbs are compatible with organic agricultural approaches [20]. Additionally, the variety of nutrients is crucial because it affects plant vegetative growth [21], which in turn affects crop quality and production as well as essential oil [22,23]. Organic and biological fertiliser applications include [24]. The equilibrium between water and nutrient uptake in the root zone, as well as the advantageous effects of these fertilizers on essential hormones and enzymes and their stimulating effects on plant growth, may be responsible for this increase. Some of these stimulants help plants respond to their surroundings, while others have an impact on both quantitative and qualitative plant performance [25]. Amino acids, like phenylalanine, are among these substances that either directly or indirectly affect physiological activities related to plant growth and development. One of the most significant amino acids, phenylalanine contributes to the synthesis of aromatic compounds and antioxidants [26]. Achieving the highest amount of biologically active chemicals and therapeutic in medicinal and aromatic plants requires careful consideration of the ideal fertilizer level based on environmental circumstances. The phytohormone controls almost every aspect of plant growth and development, including germination, cell division, stem and root growth, seed growth, and flowering time [27].

The present study was carried out to investigate the effect of different levels of Crest® PGR (Fine Americas, Walnut Grove, CA) and concentrations of phenylalanine acids on vegetative growth under greenhouse conditions of two species of lavender. (L. angustifulia, and L. intermedia).

Experimental Design and Treatments

Lavandula × intermedia ‘Provence’ and L. angustifolia ‘Hidcote’ were used in this study. Plants were grown in Mississippi State 106 University's Department of Plant and Soil Sciences greenhouses (latitude 27-33 ° N; longitude 88-47 ° W) (Figure 1) with the temperature set points at 24/20° C Day/Night.

Figure 1: Lavandula species which used of this study (L. angustifulia, and L. intermedia)

Treatment Details

Five replications of the experiment were conducted using a Randomised Complete Block Design (RCBD). For eight months (2021–2022), plants were cultivated. The plants and flowers were taken at the soil line when half of the plants were in flower. Crest® (kinetin 0.010%; Indole Butyric Acid 0.005%; Gibberellic Acid 0.005%; 0, 25, or 50 mg/L) and four fertiliser treatment levels (0, 50, 100, or 150 mg/L phenylalanine) were applied. Plant samples were rotated every day while the plants were air-dried at 20°C for a month.

Measurements

Growth metrics (plant height, number of branches, leaf area, number of flowers, fresh weight, and dried weight) were measured. The dry weight (Dw-g) of all plants (buds, flowers, leaves, and stems) was calculated by weighing dry samples, and at the conclusion of the growing season, vegetative growth was noted for every plant. The soil was also subjected to chemical and physical analyses (Table 1).

Table 1: Chemical and Physical properties of the potting soil of experimental/ Mississippi State University (Soil Testing Laboratory) (AL-Garallaa)

pH of soil is slightly acid. No lime recommended for this crop

Statistical Analysis

SAS (Version 9.4) was used to finish the experiment's data analysis. The means of the treatments was compared using the LSD test at a 5% probability level.

The experiment elements and their interaction significantly impact the plant height of the experiment, according to the results of the two-way analysis of variance in Table 2. Using (verities ×Crest 25), a notable improvement in intermediate growth was observed (plant height of 41.33 cm). The reason may be attributed to the increased plant height due to GA3 treatment as gibberellin has a role in cell division and increases cell absorption of water, which is reflected in the increase in their protoplasmic volume and the increase in the surface area of the plant, its tissues, and its size [27]. While application (verities× Crest 50) achieved (No, branches24.25, No. flowers 15.25, leaf area 17.08, fresh weight 20.87g), respectively, followed by the angustifolia (verities ×Crest 50) with heights of dry weight 9.26g (Table 2) compare to control treatment from spraying only distilled water. It was also found in Table 2 that spraying phenylalanine with a concentration of 50mg/L (verities× Ph 50mg/L) led to a significant increase in (No. branches 26.22, No. flower 12.89, leave area 18.53, fresh weight 27.11, dry weight 9.62) compared to Ph 100 g /L, while spraying phenylalanine with a concentration of 100mg/L led to a significant increase in plant height which reached 41.22 cm.

Table 2: The One-Way Effect and Two-Way Interactions for Varieties, Foliar Applications of Crest and Phenylalanine on Some Growth Parameters of Lavender, on Plant Height (Cm), No. Branches, Leaf Area, No. Flowers, Fresh Weight, and Dry Weight. Theirs Differences of Parameters at a Significance Level pf p ≤ 0.05

The three-way results showed (Table 3) that the interaction between Crest and phenylalanine resulted in more branches for the interaction between (Cr₂₅× ph₅₀) and angustifolia, where the branch number reached 23.33 and (Cr₅₀ × Ph₅₀) and angustifolia, where plant height reached 40.83 and fresh weight 19.51. The lowest mean dry weight was in the interaction of (Cr₂₅×Ph₁₀₀g / L and angustifolia, which gave 5.03g. The presence of a significant interaction of Crest50ml /L× Ph100× angustifolia, which reached 14.33 flowers/plant and 9.51 dry weight, respectively. [28] indicated that a significant increase in plant height by different levels of GA3 was observed in the number of flowers/plant. However, a significant interaction between 50ml/L Crest /L× Ph150× angustifolia produced the greatest leaf area, reaching 17.43 per plant. Moreover, the results of the three-way interaction show in Table 3 the presence of a significant interaction of Crest50ml /L× Ph50× intermedia, which reached 19.70 leave area /plant, 17.33 No. flowers, 29.15 fresh weight, and 11.12 dry weight, respectively. Well as the interaction between different concentrations of Crest25x Ph100 x intermedia had significantly statistically influenced the plant height. Plant height was the highest (51.33 cm). The application of different concentrations of Crest 0 × Ph50× intermedia had significantly influenced the number of branches /plant was found highest number of breaches/plant (31.00) compare with the control. Results showed that the interaction effects of bio-fertilizers. Phenylalanine increases plant nutrient uptake, which helps increase photosynthesis and morphological growth [28]. In terms of morphological and physiological measures, phenylalanine and Crest were significant across all treatments (Table 2, 3). In actuality, this can be the result of the many nutrients given to the plants, which enhance their growth. Applying biofertilizers may improve photosynthesis, which would boost plant development [21].

Shows that treatments have a substantial impact on plant height (cm), dry and fresh weight (g), and dry and fresh weight. Plant growth indices, such as plant height, number of branches, number of flowers, leaf area, and fresh and dry weight, exhibited the greatest increase when compared to control, phenylalanine treatments, and Crest, according to an analysis of plant growth features (Table 2, 3). Plant hormones and other growth factors are derived from amino acids. [29,30,31]. The role of amino acids in boosting photosynthesis and protein synthesis, boosting plant metabolic productivity, boosting plant tolerance to biostresses, and boosting quality characteristics can all be linked to increased plant growth [32]. When compared to the control, all foliar treatments significantly increased plant growth. When comparing the plant's appearance to its root uptake, the effects of foliar treatment are immediately ascertained [33]. However, compared to the control in thyme, Hakimi, [4] found that the amino acid treatment of phenylalanine and tryptophan at various concentrations significantly increased the plant height. (Thymus vulgaris L.). Furthermore, phenylalanine is essential for the synthesis of phenylpropanoid molecules. Increased leaf area, chlorophyll content, and photosynthetic rate result from phenylalanine's rapid elimination of plant shortages, which also has the potential to boost the product's amount and quality [34]. This was seen in daisy flowers (Bellis perennis L.) [35]. As foliar concentration rises, leaf uptake efficiency falls and may even negatively impact leaf metabolism and photosynthesis.

Table 3: Effects of Three-Way Interactions for Varieties, Foliar Applications of Crest and Phenylalanine on Some Growth Parameters of Lavender, on Plant Height (Cm), No. Branches, Leaf Area, No. Flowers, Fresh Weight, and Dry Weight. Theirs Differences of Parameters at a Significance Level of p ≤ 0.05

Lavandula dry weight was enhanced by organic treatments (Crest and Phenylalanine). Additionally, by aiding in the rooting process of plants, Crest and Phenylalanine have boosted the attraction of elements like nitrogen and phosphorus, which are important for the synthesis of chlorophyll. Improved nitrogen uptake by plants through the use of Crest and phenylalanine is another factor encouraging Lavandula growth. This has also resulted in higher cell division, increased water content of plant tissues, and increased weight gain of the shoots [36]. Plants need amino acids like phenylalanine to absorb more nutrients and minerals like phosphorus and nitrogen [37]. The enzyme phenylalanine ammonia lyase, which is essential to the metabolic signal transduction pathway, contains phenylalanine. When L-phenylalanine is applied to leaves, it can increase the uptake of nutrients like nitrogen and phosphorus, which will immediately and favourably impact plant growth [38,39]. Other researchers have also reported that phenylalanine application improves the productivity and secondary metabolites of mint (Mentha spp.) [23]. On the other hand, the interaction of biofertilizers between Crest and L-phenylalanine can help plants improve their growth and vegetative growth. Begum et al. [40] indicated that the moisture of vegetative bodies of medicinal plants should be equal to 80% to obtain dry weight of appropriate quantity and quality. There is a relationship between some factors such as light quality, seasonal and climatic variations, nutritional relationships, plant growth regulators, some abiotic stresses, and leaf length in plants [18]. Research also indicates that amino acids (phenylalanine) act as beneficial stimulants for plant growth, both quantitatively and qualitatively [41,42]. Amino acids play an important role in plant metabolism and hormonal processes [ 41,37]. As a result, their application may play a significant role in raising the yield of medicinal plants both quantitatively and qualitatively. According to Miller (1961) [43], it is clear from the initial biological effect found that kinetin should not be viewed as merely another auxin. Both kinetin and indoleacetic acid were necessary for cell division in tobacco callus tissue, and the cells continued to divide and expand in the absence of the other. The functions of kinetin may interfere with those of other plant hormones, and may be the result of their interaction [44]. In our study, Crest and phenylalanine stimulated the concentration, uptake, and accumulation of nutrients, leading to increased plant growth of two species of Lavandula [45].

Plant height, number of branches, leaf area, number of flowers, fresh weight, and dry weight were all raised by 50 mg/l of phenylalanine and 50 mg/l of Crest®.The majority of growth features were positively impacted by phenylalanine levels. The results showed that applying Crest® and phenylalanine exogenously to lavender plants significantly boosted both species' growth. For improving lavender vegetative growth in greenhouse agriculture systems, 50 mg/l Crest® was the ideal concentration. One of the biggest difficulties for the coming decades may be the development of medicinal plants in an environmentally sound and sustainable manner. Our findings show that Crest and L-phenylalanine foliar spray. have positive impacts on growth metrics, stimulation, and the synthesis of therapeutic essential oils like lavender. The most significant component of lavender's phytochemicals is its essential oil. It is a volatile combination primarily made up of sesquiterpene and monoterpene components. In general, we discovered that the possible application of L-phenylalanine and Crest of the lavender seedlings to enhance the quality of Lavandula essential oil satisfies ISO 3515 (2002) in accordance with International Slandered Lavender Oil for Pharmaceutical Purposes.

1. Gorji A. “Pharmacological treatment of headache using traditional Persian medicine.” Trends in Pharmacological Sciences, vol. 24, no. 7, 2003, pp. 331–334.
2. Bisset N.G. and Wichtl M. Herbal Drugs and Phytopharmaceuticals: A Handbook for Practice on a Scientific Basis. 1994.
3. Najafi Z. et al. “Effect of aromatherapy with lavender on sleep quality among patients undergoing hemodialysis.” Feyz Medical Sciences Journal, vol. 18, no. 2, 2014, pp. 145–150.
4. Hakimi Y. et al. “Investigation of germination characteristics of four medicinal plant seeds (lavender, hyssop, black cumin and Scrophularia) under interaction between salinity stress and temperature levels.” Journal of Genetic Resources, vol. 8, no. 1, 2022, pp. 35–45.
5. Cavanagh H.M.A. and Wilkinson J.M. “Biological activities of lavender essential oil.” Phytotherapy Research, vol. 16, no. 4, 2002, pp. 301–308.
6. Werker E. et al. “Glandular hairs and essential oil in developing leaves of Ocimum basilicum L. (Lamiaceae).” Annals of Botany, vol. 71, no. 1, 1993, pp. 43–50.
7. Denner S.S. “Lavandula angustifolia Miller: English lavender.” Holistic Nursing Practice, vol. 23, no. 1, 2009, pp. 57–64.
8. Bakhoum G.S. et al. “Improving growth, some biochemical aspects and yield of three cultivars of soybean plant by methionine treatment under sandy soil condition.” International Journal of Environmental Research, vol. 13, no. 1, 2019, pp. 35–43.
9. Almas H.I. et al. “Exogenous application of methionine and phenylalanine confers salinity tolerance in tomato by concerted regulation of metabolites and antioxidants.” Journal of Soil Science and Plant Nutrition, vol. 21, no. 4, 2021, pp. 3051–3064.
10. Adams Z.P. et al. “The regulatory role of shikimate in plant phenylalanine metabolism.” Journal of Theoretical Biology, vol. 462, 2019, pp. 158–170.
11. Teixeira W.F. et al. “Dry mass increment, foliar nutrients and soybean yield as affected by amino acid application.” Journal of Agricultural Science, vol. 11, no. 18, 2019, pp. 230–242.
12. Samani M.R. et al. “L-Phenylalanine and bio-fertilizers interaction effects on growth, yield and chemical compositions and content of essential oil from the sage (Salvia officinalis L.) leaves.” Industrial Crops and Products, vol. 137, 2019, pp. 1–8.
13. Deotale R.D. et al. “Effect of GA3 and NAA on morpho-physiological parameters of soybean.” 1998.
14. Lee H.S. “Effects of pre-sowing seed treatments with GA3 and IAA on flowering and yield components in groundnuts.” 1990.
15. Maske V.G. et al. “Influence of GA3 and NAA on growth and yield-contributing parameters of soybean.” 1998.
16. Lawrence B. “Progress in essential oils, lavender oils.” Perfumer & Flavorist, vol. 18, no. 1, 1993, pp. 58–61.
17. Wilkinson S. et al. “Plant hormone interactions: Innovative targets for crop breeding and management.” Journal of Experimental Botany, vol. 63, no. 9, 2012, pp. 3499–3509.
18. Lymperopoulos P. et al. “Phytochrome and phytohormones: Working in tandem for plant growth and development.” Frontiers in Plant Science, vol. 9, 2018, article 1037.
19. Egamberdieva D. et al. “Phytohormones and beneficial microbes: Essential components for plants to balance stress and fitness.” Frontiers in Microbiology, vol. 8, 2017, article 2104.
20. Bistgani Z.E. et al. “Application of combined fertilizers improves biomass, essential oil yield, aroma profile, and antioxidant properties of Thymus daenensis Celak.” Industrial Crops and Products, vol. 121, 2018, pp. 434–440.
21. Bajalan I. et al. “Quali-quantitative variation of essential oil from Iranian rosemary (Rosmarinus officinalis L.) accessions according to environmental factors.” Journal of Essential Oil Research, vol. 30, no. 1, 2018, pp. 16–24.
22. Narimani R. et al. “Essential oil composition of seven populations belonging to two Nepeta species from Northwestern Iran.” International Journal of Food Properties, vol. 20, Supplement 2, 2017, pp. 2272–2279.
23. Wu G. “Amino acids: Metabolism, functions, and nutrition.” Amino Acids, vol. 37, no. 1, 2009, pp. 1–17.
24. Woronuk G. et al. “Biosynthesis and therapeutic properties of Lavandula essential oil constituents.” Planta Medica, vol. 77, no. 1, 2011, pp. 7–15.
25. Thomas J. et al. “Role of biologically active amino acid formulations on quality and crop productivity of tea (Camellia sp.).” International Journal of Agricultural Research, vol. 4, no. 7, 2009, pp. 228–236.
26. Buchanan B.B. et al. “Photosynthesis.” In: Biochemistry & Molecular Biology of Plants. American Society of Plant Physiologists, Rockville, 2000, pp. 568–629.
27. Al-Garallaa K. “Phytochemical and biological strategies to improve essential oils content in lavender.” 2021.
28. Al-Mohammad M.H. et al. “Effect of phenylalanine, jasmonic acid and biofertilizer on growth, yield and anthocyanin pigments of roselle calyces.” IOP Conference Series: Earth and Environmental Science, vol. 910, no. 1, 2021, article 012077.
29. Radkowski A. and Radkowska I. “Influence of foliar fertilization with amino acid preparations on morphological traits and seed yield of timothy.” Plant, Soil and Environment, vol. 64, no. 5, 2018.
30. Zanganeh R. et al. “Role of salicylic acid and hydrogen sulfide in promoting lead stress tolerance and regulating free amino acid composition in Zea mays L.” Acta Physiologiae Plantarum, vol. 41, no. 6, 2019, article 94.
31. Hu Y. et al. “Growth performance and nitrogen allocation within leaves of two poplar clones after exponential and conventional nitrogen applications.” Plant Physiology and Biochemistry, vol. 154, 2020, pp. 530–537.
32. Calvo P. et al. “Agricultural uses of plant biostimulants.” Plant and Soil, vol. 383, no. 1, 2014, pp. 3–41.
33. Belal B.E.A. et al. “Foliar application of some amino acids and vitamins to improve growth, physical and chemical properties of flame seedless grapevines.” Egyptian Journal of Horticulture, vol. 43, no. 1, 2016, pp. 123–136.
34. Ramezanzadeh F. et al. “The effect of organic media and fertilization method on the yield and nutrients uptake of Bellis perennis L.” Journal of Ornamental and Horticultural Plants, vol. 4, no. 3, 2014.
35. Gurmanpreet K. et al. “Effect of integrated nutrient management on growth and yield of Japanese mint (Mentha arvensis L.).” Progressive Research Journal, vol. 10, no. 1, 2019, pp. 136–148.
36. Rezakhani A. and Haj Seyed Hadi M.R. “Effect of manure and foliar application of amino acids on growth characteristics, seed yield and essential oil of coriander (Coriandrum sativum L.).” Iranian Journal of Field Crop Science, vol. 48, no. 3, 2017, pp. 777–786.
37. Govindaraju S. and Arulselvi P.I. “Effect of cytokinin combined elicitors (L-phenylalanine, salicylic acid and chitosan) on in vitro propagation, secondary metabolites and molecular characterisation of medicinal herb–Coleus aromaticus Benth (L).” Journal of the Saudi Society of Agricultural Sciences, vol. 17, no. 4, 2018, pp. 435–444.
38. Li Y. et al. “The effect of developmental and environmental factors on secondary metabolites in medicinal plants.” Plant Physiology and Biochemistry, vol. 148, 2020, pp. 80–89.
39. Velička A. et al. “Impact of foliar application of amino acids on essential oil content, odor profile, and flavonoid content of different mint varieties in field conditions.” Plants, vol. 11, no. 21, 2022, article 2938.
40. Begum N. et al. “Arbuscular mycorrhizal fungi improve growth, essential oil, secondary metabolism, and yield of tobacco (Nicotiana tabacum L.) under drought stress conditions.” Environmental Science and Pollution Research, vol. 28, no. 33, 2021, pp. 45276–45295.
41. Hildebrandt T.M. et al. “Amino acid catabolism in plants.” Molecular Plant, vol. 8, no. 11, 2015, pp. 1563–1579.
42. Yu Z. and Yang Z. “Understanding different regulatory mechanisms of proteinaceous and non-proteinaceous amino acid formation in tea (Camellia sinensis) provides new insights into the safe and effective alteration of tea flavour and function.” Critical Reviews in Food Science and Nutrition, vol. 60, no. 5, 2020, pp. 844–858.
43. Rodriguez A. et al. “Establishment of a yeast platform strain for production of p-coumaric acid through metabolic engineering of aromatic amino acid biosynthesis.” Metabolic Engineering, vol. 31, 2015, pp. 181–188.
44. Miller C.O. “Kinetin and related compounds in plant growth.” Annual Review of Plant Physiology, vol. 12, no. 1, 1961, pp. 395–408.
45. Frankenberger W.T. and Arshad M. Phytohormones in Soils: Microbial Production and Function. 1996.
46. Khan N.A. et al. “Effect of gibberellic acid spray during ontogeny of mustard on growth, nutrient uptake and yield characteristics.” Journal of Agronomy and Crop Science, vol. 181, no. 1, 1998, pp. 61–63.
47. Castro P.R.C. et al. “Action of growth regulators on rape (Brassica napus L.).” 1989.