The effect of genetic variation and nitrogen fertilization on productive characters of Greek oregano

ABSTRACT

This study aims to investigate the response of 10 Greek Oregano (Origanum vulgare subsp. hirtum) populations, collected across Greece, under 3 levels of N-fertilization during 2012 and 2013. The populations were differentiated for dry matter (from 32.7 to 63.3 g·pot⁻¹), for essential oil content (from 2.31 to 5.86 ml·100⁻¹ g dry weight) and for amount of essential oil (from 1.37 to 2.46 ml·pot⁻¹), for both years. Those with the highest dry matter (1-“Palaiochori” and 5-“Gliki”) and the highest essential oil content (10-“Gytheio” and 9-“Achladocastro”) were superior by 30%, as compared to the general mean of the experiment. The populations 3-“Litochoro” and 5-“Gliki” had an increased amount of essential oil (24%) as compared to the general mean of the experiment. An additional nitrogen supply (N₀ to N₁ level) increased dry matter production and amount of essential oil per pot, while decreased essential oil content for all populations. Further increase of nitrogen supply, favored six populations for dry matter production and two populations for amount of essential oil per pot while had almost no effect on five populations for essential oil content. The superior populations could be used in a breeding program as starting material for the development of new cultivars.

KEYWORDS:

• Origanum vulgare ssp. hirtum
• nitrogen
• plant breeding
• essential oil
• genotypes

Introduction

Origanum vulgare ssp. hirtum is geographically distributed in Mediterranean-type ecosystems and mountain woodlands. It is the commonest O. vulgare subspecies in Greece (Vokou et al. 1993) that is widely used as a spice under the name ‘Greek oregano’ (Kokkini & Vokou 1989). ‘Greek oregano’, has the best quality of all similar spices and, therefore, many studies were focused on its geographical distribution and chemical features of their essential oils as collected from natural habitats (Kokkini 1997; Skoula & Harborne 2002). It is reported that the essential oil content of O. vulgare ssp. hirtum can reach up to 8%, with high percentage of carvacrol that can reach up to 95% and/or thymol (Kokkini & Vokou 1989; Kokkini et al. 1994; Johnson et al. 2004). The essential oil content and their constituents have a great variation within other Origanum species. It is reported that the essential oil content of Origanum onites is ranging from 1.8% to 4.5%, including a carvacrol content ranging from 51.0% to 84.5%; regarding the O. vulgare spp. viridulum the recorded essential oil was ranged from 0.3% to 0.8% having a carvacrol content in a range from 40.0% to 45.1%, while the essential oil of O. vulgare spp. vulgare is ranging from 0.1% to 0.3% including only traces of carvacrol (Kokkini & Vokou 1989).

However, the collection of wild aromatic and medicinal species from natural habitats for wide use, before seed set, results in low regeneration and gradual population decline (Abbad et al. 2011). Therefore, the cultivation of native species could ensure their conservation and protection in the natural habitats while allowing their sustainable utilization. For this situation, an extensive study of the necessary inputs that can affect the growth and development of medicinal and aromatic plants under cultivation is required (Jamali et al. 2014).

In the case of Greek oregano, another important motive for the optimal exploitation of its genetic variability found in Greece is the high commercial value and potential profit derived from its cultivation which can reach up to 2500 euros per hectare (Kintzios 2002). Additionally, oregano consumption has increased, not only for its use as a spice, but also because of its therapeutic benefits on human health due to antioxidative, antimicrobial and antifungal properties (Baratta et al. 1998; Rhayour et al. 2003; Gavaric et al. 2015; Adame-Gallegos et al. 2016).

Recently, several researchers investigated the factors that might affect the production and quality of oil yield of oregano species under cultivation conditions (Chatzopoulou et al. 2004; Kizil et al. 2009) or the vegetative propagation methods (Bilalis et al. 2012). The optimal combination for nitrogen supply and water availability was studied further for their influence to the production of optimum herbage and essential oil content in an O. vulgare genotype (Said-Al Ahl et al. 2009). Initially, the performance of selected populations from different subspecies of O. vulgare was investigated under different nitrogen fertilization levels and soil moisture regimes (Azizi et al. 2009). Also, selected populations of the O. vulgare ssp. viridulum were evaluated under cropping conditions, in Southern Italy (De Falco et al. 2014). Other field studies were conducted to evaluate the impact of nitrogen availability on oregano plant growth and characteristics (Sotiropoulou & Karamanos 2010; Karamanos & Sotiropoulou 2013; Dordas 2016) or the effect of calcium and magnesium foliar application to the dry matter production and oil yield (Dordas 2009). Nitrogen application affected positively the amount of essential oil production per hectare due to the increased vegetative growth, while there was no effect on oil concentration (Sotiropoulou & Karamanos 2010). In a recent study, it was found that the use of different organic fertilizers in peppermint affected the amount of essential oil, while having minor effects on the essential oil composition (Costa et al. 2013). Apart from cultivation and environmental conditions, oregano essential oil content and composition were significantly affected by genotype which has a major contribution to the observed variability of the above characteristics (Novak et al. 2003). More specifically, important variability was observed in the yield and quality of O. vulgare ssp. hirtum, among wild populations widespread in most parts of Greece (Kokkini & Vokou 1989; Vokou et al. 1993; Kokkini 1997; Gavalas et al. 2011). Despite the above, there is little available information on the impact of genotype on yield and quality and their interaction with nutrient supplies, since other researchers use only few genotypes (Azizi et al. 2009; Dordas 2009, 2016; Karamanos & Sotiropoulou 2013).

The aim of the current study was: (i) to assess the variation of yield and oil content among 10 Greek oregano (O. vulgare ssp. hirtum) populations originated from diverse geographical areas across Greece and (ii) to evaluate the response of these populations to nitrogen fertilization.

Materials and methods

Experimental set-up

The experiment was conducted in a greenhouse located at Omolio, Larissa (39°53'N, 22°38'E) during the years 2012 and 2013. Seeds of oregano (O. vulgare ssp. hirtum) were collected from 10 regions of Greece with diverse agro-climatic conditions (Figure 1 and Table 1). The collected seeds were sown in a nursery and the most vigorous uniform plants were transplanted in 7.5 l plastic pots (No. 200–23.5 × 22 cm) (five plants per pot). The soil used as substrate, was collected from a field in Omolio at a depth of 0–20 cm and had the following characteristics: loam (55% sand, 14% silt and 31% clay), pH 7.8 (1:1 H₂O), Ν 10.5 (μg·g⁻¹), P 15.7 (Olsen μg·g⁻¹), K⁺ 150 (exchangeable μg·g⁻¹), Ca⁺² 740 (exchangeable g·Kg⁻¹), Mg⁺² 105 (exchangeable μg·g⁻¹) and 1.9% organic matter. Irrigation corresponded to 80% of the water holding capacity of the pots and was maintained stable during plant growth.

Figure 1. Collection sites of Greek oregano plants in relation to the distinct floristic regions of Greece, as they are designated in Flora Hellenica (adapted from Strid & Tan 2002).

Table 1. The geographic location and the climatic characteristics (temperature and precipitation) of the collection sites of Greek oregano populations for the annual and the cultivation period (March–July) (average of the period 2010–2015).

			Temperature		Precipitation
Site	Geographic location	Altitude	Mean Annual (°C)	Mean March–July (°C)	Annual (mm)	March–July (mm)
Palaiochori-Chalkidikis	40°27'N 23°38'E	490	14.7	17.0	670.3	228.1
Nea Roda-Chalkidikis	40^o22'N 23^o58'E	90	16.7	19.2	856.1	220.6
Litochoro-Olympus	40°5'N 22°29'E	462	16.1	19.1	622.7	186.9
Omolio-Larisas	33^o53'N 22^o38'E	147	15.7	18.3	540.5	183.1
Gliki-Thesprotias	39^o19'N 20^o36'E	184	17.9	19.6	1036.0	238.0
Anilio-Pelion	39°25'N 23°08'E	245	14.8	17.4	1507.4	477.3
Monastery of Evagelismou-Skiathos	39°11'N 23°28'E	188	18.0	19.4	846.6	240.7
Metohi-Evoia	38°37'Ν 23°57'Ε	309	15.2	18.6	1527.4	392.7
Achladokastro-Etoloakarnanias	38°34'Ν 21°44'Ε	548	17.2	19.2	1173.86	277.92
Gytheio	36°45'Ν 22°33'Ε	77	18.9	19.8	618.8	145.2

Three nitrogen nutrition levels were applied: N₀ (control, without fertilization), N₁ (0.6 N g·pot⁻¹) and N₂ (1.2 N g·pot⁻¹). Ammonium nitrate (NH₄NO₃) was dissolved in water and applied to each pot in the middle of April. A dish was placed under each pot to prevent nutrient leaching, and the collected leachate in the dish was applied back to each pot before watering. Two harvests were carried out at the end of each growing cycle in 2012 and 2013. To determine dry matter production, plants were cut at 5 cm above soil level and dried in an air-circulating oven at 40°C for 4 days. Essential oils were isolated by hydro-distillation for 3 h using a Clevenger apparatus according to Europaean Pharmacopeia (EDQM 2005) and the essential oil content was expressed in ml 100⁻¹g dry weight (DW).

Statistics

Homogeneity of variances was checked for all measurements and derived data, before the analysis of variance (ANOVA). A completely randomized experimental design was conducted as a two factorial pot experiment with three replications. The 1rst factor was the nitrogen supply level with three treatments [N₀ (control, without fertilization), N₁ (0.6 N g·pot⁻¹) and N₂ (1.2 N g·pot⁻¹)] and the 2nd factor was the genotype expressed thought the 10 populations of O. vulgare ssp. hirtum, as described above. The experiment included 90 pots in total (3 nitrogen levels × 10 populations × 3 replications), while each pot contained 5 plants. Tukey’s test (P = .05) was used to find significant differences among the means. All statistical analyses were performed using the SPSS software package (ver. 18, SPSS Inc., Chicago, USA).

Results

Effects of nitrogen supply on dry matter production, and essential oil content and yield

The studied parameters were differentiated under the different nitrogen fertilization levels (Table 2). Increased nitrogen availability during plant growth has resulted in higher dry matter accumulation, up to level N₁ for both years of the experimentation, by an average of 24.0% as compared to the N₀ (Table 3). Also, it was found that N₁ level was sufficient for the achievement of the highest dry matter production for both years, since there was no significant differences with the level N₂ (Table 3).

Table 2. Over year ANOVA of Greek oregano populations and nitrogen supply levels for dry matter (g·pot⁻¹), essential oil content (ml·100⁻¹g DW) and amount of essential oil per pot (ml·pot⁻¹) and their interactions.

Mean squares	Year (Y)	Nitrogen (N)	Populations (P)	Y × N	Y × P	N × P	Y × N × P
Dry matter production	NS	***	***	NS	***	***	NS
Essential oil content	*	**	***	NS	***	**	NS
Amount of essential oil	NS	**	***	NS	***	**	NS

Notes: NS, nonsignificant.

*Significant at the .05 level of probability.

**Significant at the .01 level of probability.

***Significant at the .001 level of probability.

Table 3. Dry matter (g·pot⁻¹), essential oil content (ml 100⁻¹ g DW) and amount of essential oil per pot (ml·pot⁻¹) of the three nitrogen levels (N₀, N₁ and N₂), in 2012, in 2013 and in over year analysis of Greek oregano populations.

Treatments	Dry matter (g·pot^−1)	Essential oil content (ml·100^−1g DW)	Amount of Essential oil (ml·pot^−1)
2012
N0	39.67b^†	4.61a	1.79b
N1	49.15a	4.24b	2.02a
N2	51.40a	4.06c	2.00a
2013
N0	40.3b	4.81a	1.88c
N1	50.0a	4.40b	2.11a
N2	52.4a	4.25c	2.07b
Over year analysis
N0	39.97b	4.71a	1.84b
N1	49.58a	4.32b	2.06a
N2	51.89a	4.15c	2.04a

Note: ^†Means followed by the same letter in a column are not significantly different (Tuckey’s test, P<.05).

On the contrary, it was observed that increased nitrogen availability resulted in reduced essential oil content, with the lowest value found at the N₂ level, lower on average by 11.8% compared to N₀ (4.15 vs. 4.71 ml 100⁻¹g DW, respectively) (Table 3).

Finally, the total amount of essential oil per pot, which was estimated by multiplying the dry matter and essential oil content, was affected positively by nitrogen supply; the highest value was recorded at level N₁, which was increased by 12.4% compared to level N₀, producing 2.06 ml·pot⁻¹. The additional nitrogen supply at the N₂ level did not contribute to a further production of essential oil since no significant difference was detected (Table 2). The impact of nitrogen fertilization was similar for both years for all recorded variables, since no Y × N interactions were found (Table 2).

Differences in dry matter production, and essential oil content and yield among oregano populations

The 10 oregano populations (O. vulgare ssp. hirtum), differentiated in their dry matter production, essential oil content and amount of essential oil per pot, in both years of experimentation (Tables 2 and 4). Populations originated from areas 5 and 1 (North-East and South-Pindos floristic areas of Greece, Figure 1) produced the highest dry matter in both years of experimentation (63.3 and 60.2 g·pot⁻¹, respectively), showing a superiority of ∼30% compared to the general average of the experiment; while populations 9 and 10 accumulated the lowest dry matter, producing 34.2 and 32.7 g·pot⁻¹, respectively, which was inferior by ∼30% as compared to the general average of the experiment. However, in terms of essential oil content, the highest values were recorded in populations 10 and 9 that originated from the geographical areas Pe and StE, respectively (Figure 1). The recorded values were ∼2.5-fold higher, compared to the essential oil content of population 1, (namely 5.86, 5.51 and 2.31 ml·100⁻¹g DW, respectively) for both years. Finally, the total amount of essential oil per pot ranged from 1.37 to 2.46 ml·pot⁻¹, with the highest values recorded in populations 3 and 5, which produced 2.46 and 2.44 ml·pot⁻¹, respectively. On the contrary, the lowest production of essential oil was observed in population 1, which produced only 1.37 ml·pot⁻¹ (Tables 2 and 3).

Table 4. Dry matter (g·pot⁻¹), essential oil content (ml·100⁻¹g DW) and amount of essential oil per pot (ml·pot⁻¹) of Greek oregano populations in 2012, in 2013 and in over year analysis.

	Dry matter (g·pot^−1)			Essential oil content (ml·100^−1g DW)			Amount of Essential Oil (ml·pot^−1)
Populations	2012	2013	Over year	2012	2013	Over year	2012	2013	Over year
1 ‘Palaiochori’	57.2ab^†	63.20ab	60.2ab	2.32g	2.29e	2.31g	1.31bc	1.43c	1.37d
2 ‘Nea Roda’	40.4def	39.52de	40.0e	4.88c	5.02b	4.95c	1.96ab	1.98b	1.97bc
3 ‘Litochoro’	53.0abc	54.22bc	53.6bc	4.44d	4.81bc	4.63d	2.33a	2.59a	2.46a
4 ‘Omolio’	44.0cdef	45.39cd	44.7de	4.98bc	5.01b	5.00c	2.18a	2.27ab	2.23ab
5 ‘Gliki’	60.5a	66.10a	63.3a	3.89e	3.94d	3.92e	2.32a	2.56a	2.44a
6 ‘Anilio’	49.9abcd	50.03cd	50.0cd	3.37f	3.66d	3.51f	1.67bc	1.82bc	1.74c
7 ‘Skiathos’	47.6bcde	51.14c	49.4cd	3.59f	3.72d	3.66f	1.69bc	1.88bc	1.79c
8 ‘Metochi’	43.4cdef	43.51cd	43.5de	4.56d	4.63c	4.60d	1.98ab	2.01b	1.99bc
9 ‘Achladokastro’	37.1ef	31.22e	34.2f	5.22b	5.80a	5.51b	1.93ab	1.81bc	1.87c
10 ‘Gytheio’	34.2f	31.22e	32.7f	5.76a	5.97a	5.86a	1.97ab	1.86bc	1.92bc

Note: ^†Means followed by the same letter in a column are not significantly different (Tuckey’s test, P<.05).

Dry matter production was found to be inversely related to essential oil content. Conclusively populations 5 and 1, belonging to the SPi and NE areas, with the highest dry matter production during plant growth in both years of experimentation (Table 4) had limited essential oil content, while populations 9 and 10 with the lowest dry matter production had the highest essential oil content. Finally, it was observed that the higher amount of essential oil per pot was produced by populations 3 and 5, which were originated from the NC and SPi areas, respectively (Figure 1).

Interaction of oregano populations and nitrogen supply levels

Dry matter accumulation and amount of essential oil per pot is of great commercial value and thus, the study of the parameters affecting their production is crucial. Additional nitrogen fertilization of oregano plants up to a certain level was shown to increase their productivity. However, the significant interaction between populations and nitrogen supply levels revealed the different impact of nitrogen to the examined populations. More specifically, regarding the produced dry matter, it was observed that the increased nitrogen supply (level N₂) affected positively the accumulated biomass of populations 5, 1, 3, 7, 4 and 6, while an inferior performance was recorded for populations 10, 2, 8 and 9, as compared to the N₁ level (Figure 2(a)).

Figure 2. Interaction of nitrogen supply levels and the Greek oregano populations for (a) dry matter production (g·pot⁻¹), (b) essential oil content (ml·100⁻¹g DW) and (c) amount of essential oil per pot (ml·pot⁻¹), in 2012 and 2013.

Regarding the essential oil content, it was found that the increased nitrogen supply at N₂ level had almost no effect on populations 9, 2, 10, 8 and 1 while a clear decline was found for all the other populations by a percentage ranging from 3.4% to 10.7% (Figure 2(b)).

Finally, the detected interaction concerning the amount of essential oil per pot showed that the further increase of nitrogen supply, from N₁ to N₂ levels favored populations 1 and 3, which had increased oil yield by 6.8% and 2.4%, respectively. On the contrary, all other populations were not affected positively by the additional nitrogen supply (Figure 2(c)).

Discussion

It is generally accepted that O. vulgare ssp. hirtum (Greek oregano) has the best quality of the oregano species and important genetic variability for yield and quality was detected in Greece (Lawrence 1984; Kokkini and Vokou 1989; Vokou et al. 1993; Kokkini 1997). The essential oil content of O. vulgare ssp. hirtum can reach up to 8%, showing a range from 1.8% to 8.2% (Kokkini & Vokou 1989) revealing important genetic potential. In the current work, important variation was identified among the 10 tested populations for dry matter, essential oil content and amount of essential oil per pot in both years of the experimentation, which could be exploited for the development of an oregano breeding program aiming to the production of new cultivars. The populations with the highest dry matter production (1-‘Palaiochori’ and 5-‘Gliki’) and with the highest essential oil content (10-‘Gytheio’ and 9-‘Achladocastro’) were superior by 30%, as compared to the general mean of the experiment, while the populations 3-‘Litochoro’ and 5-‘Gliki’ had the highest amount of essential oil per pot production, increased by 24%, as compared to the general mean of the experiment (Table 4). These superior populations could be used in a network of crosses to give desirable progenies, useful as a starting material in a plant breeding program or could be introduced in the cultivation.

Also, it is reported that the climatic characteristics of the environment of origin such as temperature and dryness affects the essential oil content (Vokou et al.1993; Gavalas et al. 2011). In our study, the population with the highest essential oil content (10-‘Gytheio’) originated from southern areas (Pe) that are characterized by water scarcity and the highest average annual temperature in combination with the lower precipitation during the cultivation/growing period (March–July), as compared to the other collection sites (Table 1 and Figure 1). Moreover, the population with the highest dry matter and amount of essential oil per pot (5-‘Gliki’) was originated from an area characterized by high temperature during the cultivation/growing period (March–July), sufficient annual precipitation and limited precipitation during the cultivation/growing period (Table 1 and Figure 1).

In oregano species, Novak et al. (2003) reported that the genotype is one of the most important factors affecting quality and productivity. These wild oregano genotypes constitute the primary gene pool that could be used at the first stages of a breeding program, since, according to Fehr (1987) this is one of the most important sources of genetic variation.

Our findings showed that, a proposed cross that could give desirable progenies, could take place among populations with high dry matter (5-‘Gliki’) and high essential oil content (10-‘Githeion’ or 9-‘Achladocastro’), as they may combine both desirable productive characters. Moreover, the population 3-‘Litochoro’ is combining high dry matter production and good essential oil content (%), which means that it could be a hopeful starting material to begin within population selection.

Apart the genotypes, other parameters that affect the performance of the cultivated species are the environment and the genotype × environment (G × E) interaction. According to Simmonds (1981), it is estimated that the contribution of the genotype to the yield increase of important economic crops is about 30–60%, of the environment 10–30% and of the interaction G × E 25–45%. So, another target of our experiment was to evaluate the response of the 10 examined populations, under different nitrogen supply levels. Although the impact of nitrogen has been exhaustively investigated in traditional cultivated species, only a few references are reported in the literature regarding oregano (Azizi et al. 2009; Sotiropoulou & Karamanos 2010). Our findings support that, although oregano is adapted to natural habitats with low nutrient availability, in case of commercial agriculture, where the produced quantity is connected with economic input, a minimum nitrogen supply (N₁ level) could be beneficial for the increased dry matter production (Table 3). Previous studies have reported similar effects of nitrogen on yield of other Origanum taxa such as Origanum syriacum and Origanum × applii (Omer 1999; Barreyro et al. 2005; Ozgüven et al. 2006) of O. vulgare L. (Azizi et al. 2009) and of O. vulgare ssp. hirtum (Link) Ietswaart (Sotiropoulou & Karamanos 2010).

Our results showed that although nitrogen supply has positive effect on dry matter production, the opposite impact was found on essential oil content for both years of experimentation (Table 3), which could be explained by a higher increase of dry matter production in relation to the corresponding produced amount of oil, as reported by Azizi et al. (2009). Also, the environmental conditions affect essential oil content, as it is recorded from the collection of oregano from natural habitats with different conditions (Kokkini 1994; Gavalas et al. 2011). Other studies reported a reduction of essential oil content after nitrogen supply in O. vulgare (Azizi et al. 2009), in O. syriacum (Omer 1999) and in other species of the Lamiaceae family, such as Thymus (Baranauskiene et al. 2003) and Rosmarinus (Boyle et al. 1991). However, Sotiropoulou and Karamanos (2010) reported no nitrogen effect on oil content in O. vulgare ssp. hirtum (Link) Ietswaart, while positive nitrogen effect on this parameter was reported in Egyptian oregano (O. syriacum) by Ozgüven et al. (2006). Finally, in this work, the total amount of essential oil per pot that is important for commercial production was positively affected by nitrogen supply (Tables 2 and 3). Similar positive effect was reported on the amount of essential oil in many oregano species (Omer 1999; Barreyro et al. 2005; Ozgüven et al. 2006; Azizi et al. 2009; Sotiropoulou & Karamanos 2010).

The study of the G × E interaction has an important role in the evaluation of the genotypes and has contributed to the development of high-yielding cultivars (Kang 2002). However, the interaction of oregano populations and nitrogen supply has not been investigated in depth, since, there are studies that either evaluate only one genotype/population (Omer 1999; Barreyro et al. 2005; Ozgüven et al. 2006; Sotiropoulou & Karamanos 2010; Dordas 2016) or the G × E interaction was not estimated at all (Azizi et al. 2009). So, it should be underlined that in the current work significant interaction between populations and nitrogen supply levels for both years of experimentation was detected, which means that the examined populations responded differently to nitrogen supply (Table 2 and Figure 2). In addition, when the G × E interaction is repeatable in time as found in our study, it could be exploited in an oregano breeding program (Annicchiarico 2009). The results showed that oregano plants required an optimum level of nitrogen supply to maximize the economic results, but this level is differentiated for the populations used in this study. This evidence should be taken into account for further studies to ensure the optimum evaluation of the populations.

Conclusively, the identified variation in Greek oregano genetic resources could be exploited for the development of an oregano breeding program aiming for the production of new cultivars. The proper selection of improved oregano genotypes in combination with optimum level of nitrogen supply might maximize the agricultural potential of sustainable farming systems.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Elissavet G. Ninou is a postdoc researcher focusing on the evaluation and use of populations for sustainable growth. She has participated in many EU projects and has published research articles on plant breeding and variety water-use efficiency.

Konstantinos A. Paschalidis is a professor of Applications at Technological Educational Institute of Crete, Heraklion, Greece. He has published numerous research articles on arable and horticultural crops, focusing mainly on stress mechanisms and polyamines.

Ioannis G. Mylonas is an expert on plant breeding and biotic and abiotic stress resistance. He has published many works on plant breeding and is currently working on lifelong learning projects of American Farm School. He has participated in many EU projects related to plant breeding and has numerous published research articles.

Christos Vasilikiotis is an assistant professor at the Agro-Environmental Systems Management Department of Perrotis College in Thessaloniki, Greece. He has published articles on molecular biology and photosynthesis research.

Athanasios G. Mavromatis is an assistant professor at the Department of Agricultural Science in Aristotle University of Thessaloniki. Also, he is an invited professor in the MSc Postgraduate program of the Medicine School in the University of Thessaly. He is a specialist in Genetics and Plant Breeding and published in the last 15 years a significant number (>30) of publications on the subjects of plant science, food science and agriculture, organic breeding and exploitation of plant genetic resources.