Assessment of gamma radiation through agro-morphological characters in camellia sinensis L. (O.) kuntze.

PURPOSE: To study the effects of gamma radiation on tea seed germination, morphological changes, and genetic variation by using gamma radiation. MATERIAL AND METHOD: Fresh Tea seed material were irradiated with twenty different doses of gamma radiation such as 0, 2, 4, 6, 8, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80 90, 100, 200, 500 and 1000 Gy from Cobalt 60Co source from Regional Nuclear Agriculture Research Center, Bidhan Chandra Krishi Viswavidyalaya (BCKV), West Bengal, in between 2019 and 2020. RESULT AND CONCLUSION: The growth behavior of tea seedling was recorded under varying levels of gamma radiation and its performance at nursery stages. It was observed seed irradiated with doses from 35 Gy to 100 Gy could germinate but could not survive beyond five (05) months. When treated with higher doses as 200 Gy, 500 Gy and 1000 Gy, no seed germination takes places due to possible damages occur in the DNA structure. Screening of growth characteristics of tea plant generally monitored by the characteristics like plant height, number of leaves, number of primary branches, base diameter, and total leaf area of plants and we found that these characteristics significantly increased with the progress of time and increasing levels of gamma radiation; however, the plant height showed decreasing trend with the increasing levels of gamma radiation, which could be due to the change in chromosomal structure and genetic alteration. After 90 weeks of planting, the plant height, no. of primary branches, the number of leaves, plant base diameter, and total leaf area per plant recorded were 36.42 cm, 1/plant, 7.11/plant, 0.62 c.m, 22.92 cm2/plant respectively under the radiation level 30 Gy, whereas the corresponding figures of the above parameters at the control treatment were 85.32 cm, 1/plant, 18.84/plant, 1.18 c.m and 26.68 cm2/plant, respectively. The total plant height, no. of primary branches, the number of leaves, plant base diameter, and total leaf area per plant were significantly influenced by the rising levels of gamma radiation (up to 100 Gy), finally, after 90 weeks of planting, the maximum no. of branching was observed in the treatment of 8 Gy, 10 Gy and 15 Gy respectively. The study reveals a hitherto open the possibility of using gamma radiation on tea plant for creation of variation in the tea seed planting materials. Further studies on mutation using tea planting materials would give an insight into its mutable gene behavior.

Molecular characterization of a novel mutation in the E1 flowering gene induced by gamma irradiation in soybean.

Soybean is a typical short-day (SD) plant. It undergoes reproductive growth only when the day length becomes shorter than a critical length. Fourteen major genes/loci affecting soybean flowering and maturity period have been mapped to date. These are E1 and E7 on chr6, E1La, E1Lb, E6, E8, and J on chr4, E2 on chr10, E3 on chr19, E4 on chr20, E9 on chr6, E10 on chr8, Dt1 on chr19, and GmAGL1 on chr14. The functional allele of all these genes, except E6, E9, J, and GmAGL1, delay flowering, while the non-functional counterpart accelerates flowering and maturity. The contribution of the E1 gene in delaying flowering is highest. Four non-functional/dysfunctional allelic variants of the E1 gene are already known, which accelerates the flowering by 20-25 days and are being used in development of early maturing soybean varieties in many parts of the world. In this study, seeds of the late maturing Indian variety NRC 37 were irradiated with gamma rays to develop an early maturing variety. One early maturing variant was obtained. Molecular characterization of the gene responsible for early flowering proved it to be a non-functional variant of the E1 gene with major deletion.

Cytological behaviour of floral organs and in silico characterization of differentially expressed transcript-derived fragments associated with 'floral bud distortion' in soybean.

An attempt was made to understand the 'floral bud distortion' (FBD), an unexplored disorder prevailing in soybean. Cytological behaviour of floral reproductive organs and in silico characterization of differentially expressed transcript-derived fragments (TDFs) in symptomatic and asymptomatic soybean plants were carried out. Pollens in asymptomatic plants do not have defects in number, size, shape and function. However, in symptomatic plant, pollens were found nonviable, abnormal in shape and with reduced germination ability. Here, we employed a computational approach, exploring invaluable resources. The tissue-specific transcript profile of symptomatic and asymptomatic sources was compared to determine differentially expressed TDFs associated with FBD to improve its basic understanding. A total of 60 decamer primers produced 197 scorable amplicons, ranged 162-1130 bp, of which 171 were monomorphic and 26 were differentially regulated. Reproducible TDFs were sequenced and characterized for their homology analysis, annotation, protein-protein interaction, subcellular localization and their physical mapping. Homology-based annotation of TDFs in soybean revealed presence of two characterized and seven uncharacterized hits. Annotation of characterized sequences showed presence of genes, namely auxin response factor 9 (ARF9) and forkhead-associated (FHA) domain, which are directly involved in plant development through various pathways, such as hormonal regulation, plant morphology, embryogenesis and DNA repair.

Sucrose and raffinose family oligosaccharides (RFOs) in soybean seeds as influenced by genotype and growing location.

Sucrose content in soybean seeds is desired to be high because as a sweetness-imparting component, it helps in wider acceptance of soy-derived food products. Conversely, galactosyl derivatives of sucrose, that is, raffinose and stachyose, which are flatulence-inducing components, need to be in low concentration in soybean seeds not only for augmenting utilization of the crop in food uses but also for delivering soy meal with improved metabolizable energy for monogastric animals. In the present study, analysis of 148 soybean genotypes for sucrose and total raffinose family oligosaccharides (RFOs) contents revealed a higher variation (4.80-fold) for sucrose than for RFOs content (2.63-fold). High-performance liquid chromatography analyses revealed ranges of 0.64-2.53 and 2.09-7.1 mmol/100 g for raffinose and stachyose contents, respectively. As information concerning the environmental effects on the sucrose and RFOs content in soybean seeds is not available, we also investigated a set of seven genotypes raised at widely different geographical locations for these quality traits. Sucrose content was found to be significantly higher at cooler location (Palampur); however, differences observed for raffinose and stachyose contents across the growing locations were genotype-dependent. The results suggest that soybean genotypes grown at cooler locations may be better suited for processing soy food products with improved taste and flavor.

Gamma irradiation induced enhancement in isoflavones, total phenol, anthocyanin and antioxidant properties of varying seed coat colored soybean.

Three Indian soybean genotypes, namely, Kalitur, Hara soya and NRC37 with black, green and yellow colored seed coat respectively were gamma irradiated at a dose of 0.5, 2.0, and 5.0 kGy. The total isoflavones and total phenol content (TPC) in all the genotypes increased significantly at a dose of 0.5 and 2 kGy respectively. The anthocyanin content was high in Kalitur, while other genotypes showed no detectable amounts of it. The hydroxyl radical scavenging activity (HRSA), DPPH free radical scavenging activity (FRSA) and total antioxidant power (TAP) were highest in Kalitur with black seed coat color. However, maximum enhancement in antioxidant properties was found in NRC37 with yellow followed by Hara soya with green seed coat color at a dose of 0.5 and 2.0 kGy. It was also observed that the 3 soybean genotypes showed an increase in antioxidant constituents and antioxidative properties at lower doses of 0.5 and 2.0 kGy while, the antioxidant effects of soy seeds were either decreased or remained constant at a higher dose of 5.0 kGy. It is suggested that mild gamma irradiation enhanced the antioxidant constituents and, hence, antioxidant potential of soybean seeds.