Genotypic variability in tomato for total carotenoids and lycopene content during summer and response to post harvest temperature K.S. Shivashankara, K.C. Pavithra, R.H. Laxman, A.T. Sadashiva1 and M. George Christopher1 Division of Plant Physiology and Biochemistry ICAR - Indian Institute of Horticultural Research Bengaluru – 560 089, India E-mail: shiva@iihr.ernet.in ABSTRACT Lycopene is the major carotenoid responsible for fruit colour in tomato (Lycopersicon esculentum Mill.). However, colour of the fruit is greatly affected by high temperature prevailing during fruit growth in the summer crop. To select a genotype suitable for summer conditions that can maintain colour better, a set of 52 tomato genotypes were evaluated for lycopene, total carotenoids and for TSS during summer in Bengaluru. Among the genotypes screened, IIHR 2892 recorded very high lycopene content (328.4mg/100g dry weight) and IIHR 2866 recorded very low lycopene content (25.2mg/100g dry weight). TSS values ranged from 2.6oBrix in cv. Vybhav to 7.0o Brix in IIHR 2866. In addition, study was carried out to determine the effect of postharvest temperature on biosynthesis of lycopene in five selected tomato cultivars (Arka Rakshak, Arka Samrat, Arka Ananya, Lakshmi and Abhinava). Tomatoes harvested at breaker stage were stored at 27o C, 35o C and 40o C for ripening. High temperature reduced lycopene content in tomato fruits. Lycopene synthesis in fruits was completely inhibited above 35oC. In this study, mean lycopene content in tomatoes stored at 27o C was 3-4 times higher than that in tomatoes stored at 40o C. This indicates that in tomatoes, temperature at which the fruits are stored after harvest, is a more important factor for colour development. Key words: Tomato, temperature, total carotenoids, lycopene, total soluble solids (TSS) 1Division of Vegetable Crops, Indian Institute of Horticultural Research, Bengaluru-560 089, Karnataka, India Tomato is one of the widely consumed vegetables in the world. It is rich in compounds beneficial to health, like vitamins, carotenoids, lycopene and phenolic compounds (Palop et al, 2010; Kaur et al, 2013). Lycopene is a potent antioxidant and is thought to be responsible protect cells against oxidative damage, thereby lowering the risk of chronic diseases (Rao and Agarwal, 1999). In addition to its antioxidant properties, lycopene has also been shown to induce cell to cell communication and to modulate hormone/ immune systems and other metabolic pathways, which may also confer beneficial effects (Rao et al, 1998). Lycopene, a fat soluble carotenoid, is a precursor of β-carotene and has at least twice as much antioxidant capacity as β-carotene (Davis et al, 2003). Tomato and its products are a major source of lycopene, and contribute significantly to carotenoid intake in humans. However, processing and storage conditions of tomato may cause lycopene degradation (Nguyen and Schwartz, 1999). Isomerization and oxidation are important reactions causing lycopene degradation. The first stage of degradation is a reversible isomerization of all trans-lycopene to the less colored, more oxidizable cis isomer. Environmental factors such as oxygen, light and temperature may be very important in isomerization and autoxidation of lycopene in tomato products. Tomatoes are dried mostly at high temperatures in the presence of oxygen; dried tomato products (e.g., tomato halves, slices, quarters and powders) show highest sensitivity to oxidation (Demiray et al, 2013). Apart from processing and storage conditions, growth environment also influences development of lycopene in tomatoes. High-altitude cultivars had higher lycopene content than cultivars of the plains (Chandra et al, 2012), mainly due to the low growth temperature in the high altitude regions. Lycopene content is also affected by solar radiation and high temperature in the plains sometimes results in yellow colour of the fruit rather than red (Chandra et al, 2012). Short communication J. Hortl. Sci. Vol. 9(1):98-102, 2014 99 Genotypic variability in tomato for total carotenoids and lycopene Temperature has a significant influence on growth and development of tomato fruits (Ploeg and Heuvelink, 2005). Temperatures below 12o C and above 32o C strongly inhibit lycopene biosynthesis (Collins et al, 2006; Javanmardi and Kubota, 2006; Raffo et al, 2006; Helyes et al, 2007). High temperatures (35o C) specifically inhibit accumulation of lycopene due to stimulation of conversion of lycopene into β-carotene (Krumbein et al, 2006). Growth season and location are highly significant factors affecting lycopene concentration in tomatoes. Temperatures greater than 30o C lead to inhibition of lycopene synthesis in normal, red cultivars of tomato; when the temperature is lower than 30o C, lycopene synthesis is restored. Such effects of temperature are dependent on cultivar (Garcia and Barrett, 2006). Shi and Maguer (2000) reported that relatively high temperatures (38o C) inhibited lycopene production, while, low temperatures inhibited both fruit ripening and lycopene production. In this study, variation in lycopene content in 52 genotypes and the effect of postharvest temperature on lycopene biosynthesis in five cultivars was studied. Genotypes showing diversity in fruit colour were selected for assessing the variability during summer cultivation. Commercial cultivars with red coloured fruits were selected for postharvest temperature experiments, since, these are harvested at the breaker stage, and, full colour-development occurs only after harvest. The experiment was carried out at Indian Institute of Horticultural Research, Bengaluru, during summer of 2012. Bengaluru is located at 13o58’ N latitude, 78o E longitude and 890m above mean sea level. Uniformly ripe healthy fruits, at the red ripe stage were harvested and used in the analysis. Fruits were homogenized in a blender. Total carotenoids and lycopene content was estimated by spectrophotometric method (Lichtenthaler, 1987). Total carotenoids and lycopene were estimated by extracting five grams of the homogenized tomato sample with acetone and calcium carbonate. Extraction was repeated till the residue turned white. All the extractions were carried out under low-light conditions. Carotenoids were partitioned to hexane, dried with sodium sulphate and absorbance was read at 470nm and 503nm using a spectrophotometer (T80+ UV/ VIS Spectrophotometer, PG Instruments Ltd.). Results were expressed as mg per 100g dry weight, using Standards. Total soluble solids were measured using a digital refractometer (ARKO India Ltd., Model DG-NXT) and expressed as oBrix. Data were subjected to analysis of variance using ANOVA, and means were compared, with critical difference at P≤0.05. Significant differences were observed for lycopene and total carotenoid content among the genotypes used (Table 2). Lycopene content ranged from 25.2mg/100g dry weight in IIHR 2866, to 328.4mg/100g dry weight in IIHR 2892. Total carotenoid content also exhibited a similar trend. The range of lycopene content in the genotypes was found to be significantly higher than the range reported earlier by several workers for tomato cultivars (Kerkhofs et al, 2005; Toor and Savage, 2005; Adalid et al, 2010; Kotikova et al, 2011). Significant differences in TSS were observed among genotypes. TSS ranged from 2.6o Brix in cv. Vybhav, to 7.0o Brix in IIHR 2866. TSS is a key determinant of quality in the crop, whether for use as fresh produce or for processing. Further, TSS also contributes strongly to tomato flavor and consistency (Kaur et al, 2013). TSS range observed in the genotypes was found to be significantly higher than the range reported by workers earlier for tomato cultivars (George et al, 2004; Javanmardi and Kubota, 2006; Rai et al, 2012). Based on lycopene content, the tomato Table 1. Tomato genotypes used in the study with date of harvest and mean maximum and minimum temperatures during fruit growth period Tomato genotypes Date of Temperature during harvest fruit growth period Avg. Max. Avg. Min. IIHR 2195, IIHR 2197, IIHR 2199, IIHR 2200, IIHR 2201, IIHR 2202, IIHR 2852 27/06/2012 31.9oC 16.4oC IIHR 2853, IIHR 2854, IIHR 2855, IIHR 2856 28/06/2012 31.9oC 16.5oC IIHR 2858, IIHR 2859, IIHR 2860, IIHR 2861, IIHR 2862 29/06/2012 31.9oC 16.5oC Vybhav, Nandi, Arka Rakshak, Arka Samrat, Arka Ananya, Lakshmi, US 3140, 06/07/2012 31.3oC 17.6oC US 3380, Abhinava, IIHR 2891, IIHR 2890, IIHR 2889 IIHR 2886, IIHR 2887, IIHR 2884, IIHR 2835, IIHR 2834, IIHR 2888, IIHR 2857, 07/07/2012 31.3oC 17.6oC IIHR 2863, IIHR 2864, IIHR 2865, IIHR 2866, IIHR 2406, IIHR 2408, IIHR 2412, IIHR 2413, IIHR 2417, IIHR 2321, IIHR 2876, IIHR 2827, IIHR 2622, IIHR 2828, IIHR 2657, IIHR 2885, IIHR 2892 J. Hortl. Sci. Vol. 9(1):98-102, 2014 100 Table 2. Variation in total carotenoids, lycopene content and TSS of 52 tomato genotypes cultivated during summer of 2012 Tomato Total Lycopene TSS genotype carotenoids (mg/100g dry (o Brix) (mg/100g dry weight) weight) IIHR 2892 529.2 328.4 4.4 IIHR 2876 505.5 319.1 4.3 IIHR 2890 482.8 302.4 3.3 Abhinava 466.3 286.5 3.8 IIHR 2889 454.9 284.3 3.5 Vybhav 454.4 283.8 2.6 IIHR 2828 424.6 264.7 4.1 IIHR 2861 418.2 263.0 4.3 IIHR 2417 392.2 249.6 5.2 IIHR 2321 389.9 235.3 4.7 IIHR 2827 363.7 230.7 3.3 IIHR 2860 367.8 223.7 5.7 IIHR 2657 358.1 222.5 5.1 US 3380 355.9 218.0 3.2 Lakshmi 346.5 211.0 3.6 IIHR 2858 346.4 204.7 5.3 IIHR 2891 329.3 203.9 4.3 Nandi 335.6 199.4 3.2 IIHR 2412 316.9 193.5 4.1 IIHR 2888 308.7 189.1 4.3 IIHR 2408 304.2 187.7 3.1 US 3140 315.4 186.7 2.9 IIHR 2622 298.3 178.8 4.6 IIHR 2884 287.5 178.4 4.6 IIHR 2413 281.1 178.0 6.0 IIHR 2835 284.5 171.3 5.3 IIHR 2886 276.9 168.8 4.2 IIHR 2887 260.3 165.9 4.5 Arka Samrat 258.0 158.1 4.2 IIHR 2854 259.5 155.5 4.7 Arka Rakshak 252.5 151.6 3.2 IIHR 2857 265.3 151.5 5.5 IIHR 2853 246.4 149.9 4.8 IIHR 2885 244.2 148.2 4.1 Arka Ananya 243.9 145.5 4.1 IIHR 2834 225.0 133.3 3.9 IIHR 2862 225.0 131.9 5.6 IIHR 2195 229.4 130.5 4.5 IIHR 2863 199.2 118.7 5.8 IIHR 2855 201.8 114.9 3.9 IIHR 2197 198.2 111.5 4.9 IIHR 2859 173.2 100.7 5.1 IIHR 2856 160.3 96.3 4.5 IIHR 2201 156.7 85.7 4.9 IIHR 2202 148.7 81.8 5.1 IIHR 2199 137.7 78.1 5.4 IIHR 2200 128.6 71.4 5.5 IIHR 2852 126.3 69.3 5.1 IIHR 2406 146.4 52.1 4.9 IIHR 2865 140.2 45.3 3.5 IIHR 2864 141.4 44.7 4.5 IIHR 2866 98.2 25.2 7.0 Mean 285.8 170.8 4.5 CD (P=0.05) 25.2 17.1 0.2 genotypes were divided into six groups (Table 3). In the highest (>300mg/100g dw) and lowest (<50mg/100g dw) lycopene content groups, only three genotypes each were present. A majority of the genotypes fell in the group 100-200mg/100g dw lycopene content. Results on the effect of postharvest temperature on lycopene biosynthesis in five tomato cultivars, viz., Arka Rakshak, Arka Samrat, Arka Ananya, Lakshmi and Abhinava, indicated significant difference for total carotenoids and lycopene content (Table 4). At 27oC, all genotypes recorded highest total carotenoids and lycopene. With increase in temperature, total carotenoids and lycopene content decreased in all the genotypes. Arka Rakshak showed highest reduction in total carotenoids and lycopene content. Arka Ananya, followed by Arka Samrat, recorded lower reduction in total carotenoids and lycopene content. ‘Lakshmi’ and ‘Abhinava’ exhibited higher total carotenoids and lycopene at all the temperatures, compared to the other genotypes. Mean lycopene content of tomatoes stored at 27oC was 3-4 times higher than that at 40oC. Better lycopene content was recorded in cv. Abhinava at 35oC, and in cv. Lakshmi at 40oC. Toor and Savage (2006) reported that storage at lower temperatures (7oC) inhibited accumulation of lycopene in tomatoes, whereas, lycopene level in light-red tomatoes increased upto 3-fold at a storage temperature of 15-25oC. Farneti et al (2012) concluded that storage of tomatoes at temperatures below 12oC induced lycopene degradation. Effect of high temperature (above 30oC) on lycopene content was reported to be cultivar-specific (Garcia and Barrett, 2006). Shi and Maguer (2000) reported that relatively high temperatures (38oC) inhibited lycopene production. Similar inhibition was also observed in this study at 40oC. Further, results indicated that irrespective of the field temperature experienced, colour development in tomato was largely controlled by storage temperature in fruits harvested at the breaker stage. Total carotenoids (r = -0.9106) and lycopene (r = -0.9143) were seen to be strongly and negatively correlated with temperature in this experiment. Such strong relationship at the post-harvest stage indicates the importance of ripening temperature for colour development in tomato. A wide variation exists for lycopene content among tomato genotypes. IIHR 2892 was found to be superior in terms of lycopene content compared to other genotypes. Results show that post-harvest environmental conditions showed be considered carefully for development of good colour in tomato fruit. Variation in lycopene content in tomato is controlled by both genetic and environmental conditions (like temperature and light). 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Grouping of genotypes based on lycopene content Group Genotypes I (> 300mg/100g dw) IIHR 2892, 2890, 2876 II (250-300mg/100g dw) Abhinava, IIHR 2889, Vybhav, IIHR 2828, IIHR 2861 III (200-250mg/100g dw) IIHR 2417, IIHR 2321, IIHR 2827, IIHR 2860, IIHR 2657, US 3380, Lakshmi, IIHR 2858, IIHR 2891 IV (150-200mg/100g dw) Nandi, IIHR 2412, IIHR 2888, IIHR 2408, US 3140, IIHR 2622, IIHR 2884, IIHR 2413, IIHR 2835, IIHR 2886, IIHR 2887, Arka Samrat, IIHR 2854, Arka Rakshak, IIHR 2857 VI (100-150mg/100g dw) IIHR 2853, IIHR 2885, Arka Ananya, IIHR 2834, IIHR 2862, IIHR 2195, IIHR 2863, IIHR 2855, IIHR 2197, IIHR 2859 VII (50-100mg/100g dw) IIHR 2856, IIHR 2201, IIHR 2202, IIHR 2199, IIHR 2200, IIHR 2852, IIHR 2406 VIII (< 50mg/100g dw) IIHR 2865, IIHR 2864, IIHR 2866 J. Hortl. Sci. 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