Overexpression of <i>Arabidopsis thaliana</i> gibberellic acid 20 oxidase (AtGA20ox) gene enhance the vegetative growth and fiber quality in kenaf (<i>Hibiscus cannabinus</i> L.) plants

Abstract

Kenaf (Hibiscus cannabinus L.; Family: Malvaceae), is multipurpose crop, one of the potential alternatives of natural fiber for biocomposite materials. Longer fiber and higher cellulose contents are required for good quality biocomposite materials. However, average length of kenaf fiber (2.6 mm in bast and 1.28 mm in whole plant) is below the critical length (4 mm) for biocomposite production. Present study describes whether fiber length and cellulose content of kenaf plants could be enhanced by increasing GA biosynthesis in plants by overexpressing Arabidopsis thaliana Gibberellic Acid 20 oxidase (AtGA20ox) gene. AtGA20ox gene with intron was overexpressed in kenaf plants under the control of double CaMV 35S promoter, followed by in planta transformation into V36 and G4 varieties of kenaf. The lines with higher levels of bioactive GA (0.3–1.52 ng g−1 fresh weight) were further characterized for their morphological and biochemical traits including vegetative and reproductive growth, fiber dimension and chemical composition. Positive impact of increased gibberellins on biochemical composition, fiber dimension and their derivative values were demonstrated in some lines of transgenic kenaf including increased cellulose content (91%), fiber length and quality but it still requires further study to confirm the critical level of this particular bioactive GA in transgenic plants.

Interactive effect of gibberellic acid and NPK fertilizer combinations on ramie yield and bast fibre quality

“…Fibre elongation rate was also maximized by spraying with GA 3 and fertilizing with NPK. Similarly, in transgenic kenaf and populus trees that over express gibberellic acid, the increased GA has a positive impact on fibre number, length, diameter, and wall thickness 27 .…”

“…Similarly, long okra fibres are stronger than short fibres because unlike long cells, short fibre cells require many weak connecting points in order to form fibre strands 29 . According to Withanage et al ., enhanced bioactive GA is extremely important for increasing the length of kenaf fibre and can be obtained by over expressing the Arabidopsis thaliana gibberellic acid 20 oxidase gene (AtGA20ox) in transgenic kenaf plants 27 .…”

Comparative transcriptomics of stem bark reveals genes associated with bast fiber development in Boehmeria nivea L. gaud (ramie)

“…A recent study of transcriptomic profiling of hemp bast fibres at different developmental stages revealed that GA biosynthesis is significantly increased in the bark of bottom stem of hemp [2]. In addition, recent studies in ramie have also supported the role of GA in bast fiber development [4,49], and overexpression of the Arabidopsis gibberellic acid 20 oxidase (AtGA20ox) enhances vegetative growth and fiber quality in kenaf (Hibiscus cannabinus L.) plants [50,51]. GA was also proposed to function through promoting cambia cell proliferation to increase the cell amount of phloem tissue in Arabidopsis [52].…”

Comparative transcriptomics of stem bark reveals genes associated with bast fiber development in Boehmeria nivea L. Gaud (ramie)

“…A recent study of transcriptomic profiling of hemp bast fibres at different developmental stages revealed that GA biosynthesis is significantly increased in the bark of bottom stem of hemp [2]. In addition, recent studies in ramie have also supported the role of GA in bast fiber development [4,40], and overexpression of the Arabidopsis gibberellic acid 20 oxidase (AtGA20ox) enhances vegetative growth and fiber quality in kenaf (Hibiscus cannabinus L.) plants [41,42]. GA was also proposed to function through promoting cambia cell proliferation to increase the cell amount of phloem tissue in Arabidopsis [43].…”