Effects of Septoglomus viscosum inoculation on biomass yield and steviol glycoside concentration of some Stevia rebaudiana chemotypes

Stevia rebaudiana Bertoni, a sweetener plant, has been cultivated in Indonesia since the early 1980s, but the yield is lower than in other countries. Five selected introduced stevia clones were planted at Megamendung, Bogor, Indonesia (6°39’ S, 106°56’ E, 800 m above sea level) on December 2014 until November 2015 to evaluate their growth and biomass yield. The growth and yield were observed from 6 to 12 months after planting. In addition, stevioside, rebaudioside A (reb A), and total steviol glycoside (TSG) contents of leaves were measured using high performance liquid chromatography (HPLC). At six months after planting, stem diameter was 8-11 mm, plant canopy diameter was 23-30 cm, plant height was 24-35 cm, and plant mortality was less than 5% except for clone BU at 30.7% due to Sclerotium attack. The plants flowered at different times, therefore had different harvest durations, from 4 weeks (clone BM) to 8 weeks (clone BP). The highest leaf yield was clone BM (6.04 ton ha-1 per year), followed by BX (4.91 ton ha-1 per year), and BP (4.38 ton ha-1 per year). From the five clones tested, clone BM was the best for leaf, TSG, and stevioside yields; whereas clone BS and BP were the best for reb A yield. Keywords: rebaudioside A, Stevia rebaudiana, stevioside, total steviol glycoside

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Daminozide Enhances Vigor and Steviol Glycoside Yield of Stevia (Stevia rebaudiana Bert.) Propagated in the Temporary Immersion Bioreactor

10.21203/rs.3.rs-1223930/v1 ◽

2022 ◽

Author(s):

Rizka Tamania Saptari ◽

Rizkita Rachmi Esyanti ◽

Riza Arief Putranto

Keyword(s):

Stevia Rebaudiana ◽

Feedback Regulation ◽

Optimum Concentration ◽

Temporary Immersion Bioreactor ◽

Temporary Immersion ◽

Steviol Glycoside ◽

Kaurenoic Acid ◽

Biosynthesis Gene ◽

Inhibitor Treatment ◽

Ga Biosynthesis

Abstract Stevia (Stevia rebaudiana Bertoni) contains sweet compound widely used as natural sweetener, steviol glycoside (SG). SG is a diterpenoid secondary metabolite synthesized from ent-kaurenoic acid, the same precursor of Gibberellin (GA). Therefore, in this study, a GA inhibitor, Daminozide (0, 10, 20 ppm) was used to block ent-kaurenoic acid conversion towards GA synthesis in attempt to increase SG content of stevia propagated in Temporary Immersion Bioreactor (TIB). Daminozide in 10 mg/L was observed to be the optimum concentration which increased biomass weight and SG content (stevioside and rebaudioside A) up to 40%. The treatment also increased transcripts accumulation of genes enrolled in SG biosynthesis, such as SrKA13H, SrUGT85C2, and SrUGT76G1, indicating SG pathway become more active due to the inhibition of GA pathway. Furthermore, the inhibition of GA was also indicated by the upregulated expression of GA biosynthesis gene (GA3ox) as the result of feedback regulation, and the downregulated expression of GA catabolism gene (GA2ox2) as the result of feed-forward regulation caused by inhibitor treatment.

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