Expression of γ-tocopherol methyltransferase gene from Brassica napus increased α-tocopherol content in soybean seed

Abstract

A cDNA encoding γ-tocopherol methyltransferase from Brassica napus (BnTMT) was overexpressed in soybean [Glycine max (L.) Merr.] under the control of seed-specific promoter of Arabidopsis fatty acid elongase 1 (FAE1) or soybean glycinin G1. Two and three transgenic plants were selected, respectively, after Agrobacterium-mediated transformation. Polymerase chain reaction (PCR) and Southern blots confirmed that BnTMT was single-copy integrated into the genome of transgenic plants. RT-PCR analysis showed that the expression of BnTMT was higher in the immature cotyledons than in the mature cotyledons, while no expression was detected in the leaves. Moreover, the expression level under the control of FAE1 was higher than that of G1. HPLC analysis indicated that the seed-specific expression of BnTMT resulted in 11.1-fold and 18.9-fold increase in α-and β-tocopherol content, respectively, in T 2 seed. These results suggested that introducing BnTMT into soybean can be used to increase the vitamin E composition in seeds.Additional key words: fatty acid elongase 1, Glycine max, glycinin, RT-PCR, Southern blot, transgenic plants. ⎯⎯⎯⎯

Engineering Complex Metabolic Pathways in Plants

“…However, when the gene was expressed using a seed-specific promoter, there was a 41-fold increase in α-tocopherol levels, suggesting that the endogenous pathway in the seeds is biased in favor of the α branch (89). The overexpression of γ-TMT had no effect on total tocopherol or tocotrienol levels in Arabidopsis, soybean and perilla seeds, or lettuce leaves, but the α-tocopherol content increased significantly (26,87,91,141,148,172). However, the same enzyme promoted the accumulation of α-tocotrienol in rice seeds, suggesting that different species have a latent biochemical bias that reflects the abundance of downstream enzymes, which can be revealed by increasing the general flux through the pathway (172).…”

Engineering Nutritionally Improved Edible Plant Oils

“…The conversion of γto α-tocopherol catalyzed by γ-TMT is found to be the rate-limiting factor that influences the tocopherol composition (Arun et al 2014). Elevating vitamin E through metabolic engineering was also demonstrated by overexpression of γ-TMT (Arun et al 2014, Chen et al 2012, Jiang et al 2016, Shintani & DellaPenna 1998, G.Y. Zhang et al 2013, L. Zhang et al 2013.…”

Antioxidant Green Factories: Toward Sustainable Production of Vitamin E in PlantIn VitroCultures

“…Arabidopsis leaves (At) 81 1.44 [18 pmol mg −1 (FW)] Arabidopsis leaves (Mi) 82 2.58 [31 μg g −1 (FW)] tomato leaves (Mi) 82 2.67 [11.5 μg g −1 (FW)] tomato fruits (Mi) 82 5.0 [10.3 μg g −1 (FW)] potato leaves (At) 83 2.12 [15.68 μg g −1 (FW)] potato tubers (At) 83 3.66 [1030.7 ng g −1 (FW)] lettuce leaves (Ls) 84 4.0 [25.6 μg g −1 (FW)] Brassica napus (Sy) 85 1.5 [252 mg kg −1 oil) HPT (VTE2) tomato leaves (Md) 86 3.6 (36.83 μg/g FW) tomato fruits (Md) 86 1.7 (4.57 μg/g FW) potato tubers (At) 83 2.0 [578.6 ng g −1 (FW)] tobacco leaves (At) 87 5.4 [12.09 μg g −1 (FW)] Arabidopsis seeds (At) 88 1.33 (5.2 mg α-TE 100 g −1 tissue) tomato mature leaves (Sy) 89 2.5 [500 ng mg −1 (DW)] MPBQ (VTE3) soybean (At) 90 2.5 [75 ng mg −1 (seed)] TC (VTE1) lettuce leaves (At) 91 2.24 [4.7 μg g −1 (FW)] tobacco leaves (At) 87 4.0 [8.96 μg g −1 (FW)] γ-TMT (VTE4) soybean (At) 90 8.0 [240 ng mg −1 (seed)] Arabidopsis seed (At) 92 93.4 [342 ng mg −1 (seed)] Arabidopsis seeds (At) 88 9.1 (35.6 mg α-TE 100 g −1 tissue) soybean seed (Pf) 93 10.4 (450.1 pmol mg −1 tissue) soybean seed (Bn) 94 11.1 [340 μg g −1 (DW)] Brassica juncea seeds (At) 95 6.6 [367 ng mg −1 (seed)] lettuce leaves (At) 96 3.1 [0.37 mg g −1 (DW)] Perilla f rutescens leaves (At) 97 1.8 (87.8 μg g −1 tissue) Perilla f rutescens seeds (Pf) 98 22.5 [1.31 mg g −1 (seed)] tobacco seeds (At) 23 9.6 [120 μg g −1 (FW)] VTE2+VTE1 tobacco leaves (At+At) 87 7.1 [15.90 μg g −1 (FW)] VTE3+VTE4 soybean (At+At) 90 9.1 [273 ng mg −1 (seed)] VTE2+VTE4…”