Cloning And Functional Identification Of Vitamin E Biosynthesis Genes MtHPT1 And MtTMT In Medicago Truncatula

Vitamin E, a plant secondary metabolites, closely related to human health and animal feed is mainly exists in oil crops. Therefore, developing oil seed crops with higher vitamin E components is an important breeding objective. The metabolic pathway of Vitamin E is well studied in Medicago truncatula but still some part of this mechanism is not fully explored. So, in this study, two important genes “Mt HPT1 and Mt TMT” related to this mechanism were cloned and ligated in expression vector “p B2WG7” to characterize their function. These genes were transformed in wild type and mutant Arabidopsis thaliana through Agrobacterium mediated transformation. The important findings of this study were as follow:1. The overexpression of Mt HPT1 increased the vitamin E contents 21% to 33% in the wild-type A. thaliana seeds. The overexpression of Mt TMT in wild-type A. thaliana boosts up the α-tocopherol content from 3.2% to 7.1%-66.3%. The complementation of Mt TMT in A. thaliana mutant’s vte4-3, vte4-4, make it’s completely wild type character restoration.2. The q RT-PCR analyses were done to check the expression level of Mt HPT1 and Mt TMT’s in different tissues of M. truncatula. The results showed that both these genes have high expression level in leaves and low level in roots.3. The expression patterns of Mt HPT1 and Mt TMT were also examined under different abiotic stresses like salt(Na Cl), cold and heat stress. The change of Vitamin E content was observed under such stresses. Both the genes showed similar pattern of change in the expression level under the stress treatments. A decrease trend was observed in the expression level of both the genes under cold stress. The salt treatment showed a decrease and then an increase trend in the expression level while an increase, decrease and at the end again an increase inclination were observed under heat treatment. A slight increase in the vitamin E contents were monitored under heat and salt treatment while a very little change occurred due to cold treatment.4. An observational study was conducted on wild type M. truncatula “R108” and mutant “tmt”. There were some variations in tmt and R108’s seeds, leaves, pods, the types of tocopherol etc were observed. The growth period of tmt mutant was 2 weeks longer than R108. The tmt’s leaves were bigger with extended petiole. The young tmt plants have frequently four or five leaves while a little α-tocopherol amount was examined in both seeds and leaves.