K. S. Shivashankara

Genotypic variability for antioxidant and quality parameters among tomato cultivars, hybrids, cherry tomatoes and wild species.

BACKGROUND Wide germplasm diversity and transferability of antioxidant parameters is the primary requirement for the development of high-antioxidant tomato cultivars. The present study was conducted to screen tomato genotypes including hybrids, varieties, cherry tomatoes, wild species, elite germplasm lines, interspecific hybrids and backcross populations for antioxidant activity and other quality parameters to select high-antioxidant lines with good total soluble solids (TSS) for further usage in crop improvement programmes. RESULTS Wild species and interspecific hybrids between LA-1777 (Solanum habrochaites) and an elite genotype 15SBSB recorded very high antioxidant capacity (FRAP), DPPH radical-scavenging ability, and high phenols and flavonoids. Interspecific hybrids also recorded very high total soluble solids (TSS). Significantly higher total carotenoids, lycopene and vitamin C were observed in IIHR-249-1 with moderately higher TSS. Cherry tomato lines IIHR-2866, 2865 and 2864 recorded four to five times more β-carotene than commercial hybrids/varieties. CONCLUSION Tomato line IIHR-249-1 can be used for improving antioxidant capacity, total carotenoids and lycopene in tomato breeding programmes. Cherry tomato lines IIHR-2866, 2865 and 2864 can be used for improving β-carotene content. LA-1777 and interspecific hybrids could be used for developing tomato lines rich in antioxidants as well as TSS.

Species Variability for Fruit Antioxidant and Radical Scavenging Abilities in Mulberry

Fruits from five accessions of mulberry (Morussp.) representing Morus nigra, Morus lavigeta, and Morus alba were evaluated for ferric reducing antioxidant potential, diphenyl picryl hydrazyl radical scavenging ability, total phenols, flavonoids, anthocyanins, and ascorbic acid contents. In fresh fruits, higher antioxidant capacity was found in M. nigra followed by M. lavigeta and the lowest capacity was observed in M. alba. Higher ferric reducing antioxidant potential and diphenyl picryl hydrazyl scavenging capacities were mainly due to higher anthocyanins. Among the black accessions evaluated, Acc. No. 362 and 497 recorded the highest ferric reducing antioxidant potential (4,515.75 and 4,224.24 mg ascorbic acid equivalent antioxidant capacity 100 g−1 dry wt, respectively), diphenyl picryl hydrazyl (IC50 values of 0.124 and 0.116 mg−1, respectively), and anthocyanin (4,255.65 and 4,103.93 mg/100 g−1 dry wt, respectively) content when compared to other accessions. Accession number 249 (M. alba) with white colored fruits recorded the lowest antioxidant capacity. A phenolic acid profile of fruits indicated that these accessions are rich in caffeic and gallic acids. Gentisic and protocatechuic acids were also found in fairly good quantities. Dried fruits also recorded very high antioxidant (0.18–2.32 g ascorbic acid equivalent antioxidant capacity 100 g−1 dry weight) and diphenyl picryl hydrazyl radical scavenging abilities (IC50 of 0.3–2.98 mg, quantity needed for removing 50% of diphenyl picryl hydrazyl radicals). Results indicated that black mulberry fruits could be used for preparation of high antioxidant postharvest products.

Role of oxidative stress and the activity of ethylene biosynthetic enzymes on the formation of spongy tissue in 'Alphonso' mango.

Spongy tissue formation in ‘Alphonso’ mangoes (Mangifera indica L) is a major national problem leading to loss for farmers and traders. Spongy tissue is whitish sponge like tissue formed near the seed with insipid taste and off odour. Lipid peroxidation of membranes as studied by malondialdehyde formation was significantly higher in spongy tissue. Activities of antioxidative enzymes like superoxide dismutase, catalase, peroxidase and polyphenol oxidase were lower in spongy tissue. Among the antioxidative enzymes, activities of catalase and peroxidases were severely reduced leading to membrane damage in spongy tissue. A significant reduction in 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase and accumulation of ACC was also observed in spongy tissue. However, ACC synthase activity in spongy tissue was more compared to healthy tissue. Results indicate that the membrane peroxidation leading to lower activity of ACC oxidase might lead to the formation of spongy tissue in ‘Alphonso’ mango.

Impact of Climate Change on Fruit and Vegetable Quality

Nutritional quality of fruits and vegetables depends on genetic and environmental factors. Soil factors, temperature, light and CO2 are the major factors which determine the quality of horticulture produce. Most of the health-benefiting nutrients including vitamins, minerals and antioxidants are supplied through fruits and vegetables. However, the changed climate has affected the quality of many fruits and vegetables. Elevated CO2 has improved the vitamin C, sugars, acids and carotenoids in oranges, tomatoes and strawberries. Positive effect of CO2 was also observed on total antioxidant capacity, phenols and anthocyanins in fruits and oil palm. However, elevated CO2 may decrease the protein and mineral content of the produce. High-temperature stress is known to decrease vitamin C, starch, sugars and many antioxidants especially anthocyanins and volatile flavour compounds in fruits. Deficit irrigation increases sugars, anthocyanins and even volatiles in strawberries and tomatoes. However, severe stress decreases the quality of fruits and vegetables. A higher temperature coupled with water stress is going to definitely reduce the fruit and vegetable quality in terms of vitamins, antioxidants and minerals.

Improvement in shelf life of minimally processed cilantro leaves through integration of kinetin pretreatment and packaging interventions: Studies on microbial population dynamics, biochemical characteristics and flavour retention

Effect of integrating optimized combination of pretreatment with packaging on shelf life of minimally processed cilantro leaves (MPCL) was appraised through analysis of their sensory attributes, biochemical characteristics, microbial population and flavour profile during storage. Minimally pretreated cilantro leaves pretreated with 50ppm kinetin and packed in 25μ polypropylene bags showed a shelf life of 21days. Optimized combination helped in efficiently maintaining sensory parameters, flavour profile, and retention of antioxidants in MPCL until 21days. Studies conducted on the effect of optimized combination on microbial population and flavour profile revealed that among different microorganisms, pectinolysers had a significant effect on spoilage of MPCL and their population of ⩽3.59logcfu/g was found to be acceptable. Principal component analysis of headspace volatiles revealed that (E)-2-undecenal, (E)-2-hexadecenal, (E)-2-tetradecenal & (E)-2-tetradecen-1-ol in stored samples clustered with fresh samples and therefore, could be considered as freshness indicators for MPCL.

Volatile Aroma and Antioxidant Quality of ‘Shiraz’ Grapes at Different Stages of Ripening

Wine quality is determined by the stage of harvest of grapes. In order to understand the effect of ripening stages on the berry aroma and antioxidant quality, berries were grouped into three categories, namely: (a) full ripe (before skin shriveling); (b) partially shriveled; and (c) 75% shriveled berries. Total terpenoids, alcohols, hydrocarbons, radical scavenging capacity (DPPH), and total anthocyanins were higher in grapes harvested at full ripe stage, when compared to other stages. Therefore, for better aroma and antioxidants in wines, grapes should be harvested at full ripe (no shriveled berries) stage instead of overripe shriveled berry stages.

Antioxidant Protection Mechanism During Abiotic Stresses

Abiotic stresses are the major constraints for plant growth and productivity. Adverse effects of abiotic stresses are primarily by the production of various reactive oxygen species (ROS). Reactive oxygen species are broadly categorized into superoxides (O2•−), hydroxyl radicals (OH•), alkoxyl radicals (RO•), peroxyl radicals (ROO•), singlet oxygen (1O2), lipid hydroperoxides (ROOH), hydrogen peroxides (H2O2), and excited carbonyls (RO*). In plants the major sites of ROS production are peroxisomes and chloroplast. Other sites of ROS production are apoplast, cell membrane, endoplasm reticulum, and cell wall. Production of ROS in excess results in lipid peroxidation of membranes, protein degradation, pigment bleaching, and damage to nucleic acids ultimately resulting in cell death. Plants are protected against oxidative stress by enzymatic and non-enzymatic antioxidant mechanisms. Enzymatic antioxidant system include enzymes such as superoxide dismutase (SOD), peroxidase, monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), catalase (CAT), glutathione reductase (GR), ascorbate peroxidase (APX), glutathione peroxidase (GPX), guaiacol peroxidase (GPOX), glutathione S-transferase (GST), and polyphenol oxidase (PPO), whereas non-enzymatic antioxidants include ascorbic acid (AA), α-tocopherol, reduced glutathione (GSH), carotenoids, phenolic acids, anthocyanins, flavonoids, and proline. In addition to creating oxidative stress, ROS also act as signalling molecules leading to the expression of many genes involved in stress tolerance, control of cell cycle, cell elongation, osmolyte accumulation, and other systemic responses. The present review covers the biochemistry of ROS synthesis, their scavenging mechanisms, types of ROS, effect of abiotic stresses on their production, and their impact on horticultural crops.

Salicylic Acid Induces Changes in Mango Fruit that Affect Oviposition Behavior and Development of the Oriental Fruit Fly, Bactrocera dorsalis.

The Oriental fruit fly, Bactrocera dorsalis (Hendel) is an important quarantine pest around the globe. Although measures for its control are implemented worldwide through IPM and male annihilation, there is little effect on their population. Hence, there is a need for new strategies to control this minacious pest. A strategy that has received negligible attention is the induction of ‘natural plant defenses’ by phytohormones. In this study, we investigated the effect of salicylic acid (SA) treatment of mango fruit (cv. Totapuri) on oviposition and larval development of B. dorsalis. In oviposition choice assays, gravid females laid significantly less eggs in SA treated compared to untreated fruit. Headspace volatiles collected from SA treated fruit were less attractive to gravid females compared to volatiles from untreated fruit. GC-MS analysis of the headspace volatiles from SA treated and untreated fruit showed noticeable changes in their chemical compositions. Cis-ocimene and 3-carene (attractants to B. dorsalis) were reduced in the headspace volatiles of treated fruit. Further, reduced pupae formation and adult emergence was observed in treated fruit compared to control. Increased phenol and flavonoid content was recorded in treated fruit. We also observed differential expression of anti-oxidative enzymes namely catalase (CAT), polyphenoloxidase (PPO) and peroxidase (POD). In summary, the results indicate that SA treatment reduced oviposition, larval development and adult emergence of B. dorsalis and suggest a role of SA in enhancing mango tolerance to B. dorsalis.

Profiling of anthocyanins and carotenoids in fruit peel of different colored mango cultivars

Mango cultivars are broadly categorized into green, yellow, and red types based on their peel colors. Anthocyanins and carotenoids are the most important pigments responsible for the color of fruits. The information available on the composition of pigments on mango peel was scanty, and the exact role of anthocyanins and carotenoids in imparting peel color was not clear. The present study was aimed at profiling anthocyanin and carotenoid pigments in the peels of green (‘Langra’, ‘Amrapali’, ‘Hamlet’ and ‘Bombay No. 1’), yellow (‘Arka Anmol’, ‘Lazzat Baksh’, ‘Peach’ and ‘Banganapalli’) and red (‘Tommy Atkins’, ‘Lalmuni’, ‘Gulabi’ and ‘Janardhan Pasand’) colored mango cultivars through liquid chromatography and mass spectrometry at different stages of ripening. The analysis helped in the identification of eight carotenoids and 24 anthocyanins in mango peel. Higher levels of carotenoids were observed in yellow colored cultivars, and major compounds were β-carotene and violaxanthin. Further, the red colored types were found to possess the higher anthocyanin content than green and yellow types. The major groups of anthocyanin compounds include cyanidin, peonidin, petunidin, delphinidin and pelargonidin. During fruit ripening, a significant increase in carotenoids content, and no or marginal rise in anthocyanin content was observed in mango peels. The results, show the status of carotenoids and anthocyanins in mango peel of different colored cultivars and their developmental pattern during ripening.

Morphological diversity of trichomes and phytochemicals in wild and cultivated eggplant species

An attempt was made to understand the diversity of trichomes both at morphological and chemical levels in wild (Solanum viarum, S. mammosum, S. indicum, S. gilo, S. torvum) and cultivated eggplant (S. melongena) species. Cultivated and wild eggplant species have morphologically and chemically diverse trichomes. The presence of specific type of trichomes, their densities and chemical composition varied across species. The wild species viz., S. viarum and S. mammosum have seven (Type II to VIII) morphologically distinguishable types of trichomes including two types of glandular trichomes (Type VI, VII) as against uniform occurrence of branched stellate trichomes (Type VIII) alone in cultivated species. Differences among the phytochemicals viz., phenols and flavonoid levels were also observed across the eggplant species and type of trichomes.