Uniconazole-induced starch accumulation in the bioenergy crop duckweed (Landoltia punctata) I: transcriptome analysis of the effects of uniconazole on chlorophyll and endogenous hormone biosynthesis

Abstract

BackgroundDuckweed is a novel aquatic bioenergy crop that is found ubiquitously throughout the world. Uniconazole plays an important role in improving crop production through the regulation of endogenous hormone levels. We found that a high quantity and quality of duckweed growth can be achieved by uniconazole application, although the mechanisms are unknown.ResultsThe fronds of Landoltia punctata were sprayed evenly with 800 mg/L uniconazole. The dry weight following treatment increased by 10% compared to the controls at 240 h. Endogenous cytokinin (CK) and abscisic acid (ABA) content both increased compared to the control, while the level of gibberellins (GAs) decreased. Additionally, gene expression profiling results showed that the expression of transcripts encoding key enzymes involved in endogenous CK and ABA biosynthesis were up-regulated, while the transcripts of key enzymes for GAs biosynthesis were down-regulated. On the other hand, chlorophyll a and chlorophyll b contents were both increased compared with the control. Moreover, the net photosynthetic rate was elevated to 25.6 μmol CO2/m2/s compared with the control value of 22.05 μmol CO2/m2/s. Importantly, the expression of some chlorophyll biosynthesis-related transcripts was up-regulated.ConclusionUniconazole treatment altered endogenous hormone levels and enhanced chlorophyll content and net photosynthetic rate in duckweed by regulating key enzymes involved in endogenous hormone and chlorophyll biosynthesis. The alterations of endogenous hormones and the increase of chlorophyll and photosynthetic rate data support the increase of biomass and starch accumulation.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0246-7) contains supplementary material, which is available to authorized users.

Root‐tip cutting and uniconazole treatment improve the colonization rate of Tuber indicum on Pinus armandii seedlings in the greenhouse

“…Uniconazole is a triazole chemical that is used as a plant growth retardant. It is active on a wide range of plants and acts by inhibiting the production of gibberellins (Liu et al , ). In the present study, a colonization rate increase was observed in uncut colonized seedlings under 10 mg l −1 uniconazole treatment.…”

“…However, how root‐tip cutting affects the colonization rate of the host plant by ectomycorrhizal fungi under greenhouse conditions remains unknown. Uniconazole is a well‐known plant growth regulator (Jiang et al , ; Jiang et al , ; He et al , ) that regulates plant endogenous hormone levels and gene expression (Sasaki et al , ; Liu et al , ). The morphology and biomass allocation of Salvia miltiorrhiza was reportedly altered by uniconazole (Gao et al , ).…”

Utility of Duckweeds as Source of Biomass Energy: a Review

“…The quantity (dry weigh basis) of carbohydrate, starch, crude protein, crude fibre and lipid has been reported in the ranges of 17.6-35 %, 21-38 %, 16-41.7 %, 8.8-15.6 % and 4.5-9 %, respectively, by various researchers [24,[39][40][41]. However, concentration of lipid and starch seems comparatively lower in duckweed as compared to other plant biomasses that can be further enhanced considerably through plant growth conditions manipulations (like pH, temperature and nutrient concentration in culture substrates) [24,40,[42][43][44][45]. The major constituents of carbohydrate in duckweed biomass are 20.3 % pectin (including galacturonan, xylogalacturonan, rhamnogalacturonan), 3.5 % hemicellulose (comprising xyloglucan and xylan) and 0.03 % phenolic compounds [46].…”

Abscisic acid-enhanced starch accumulation of bioenergy crop duckweed (Spirodela polyrrhiza)

“…Plant growth regulators could improve the yield of duckweed starch for bioethanol production. 14 Liu et al 15 sprayed Landoltia punctata fronds with 800 mg L À1 uniconazole and found high starch accumulation, a dry-weight starch content of up to 48%.…”