Uniconazole-induced starch accumulation in the bioenergy crop duckweed (Landoltia punctata) II: transcriptome alterations of pathways involved in carbohydrate metabolism and endogenous hormone crosstalk

Abstract

BackgroundLandoltia punctata is a widely distributed duckweed species with great potential to accumulate enormous amounts of starch for bioethanol production. We found that L. punctata can accumulate starch rapidly accompanied by alterations in endogenous hormone levels after uniconazole application, but the relationship between endogenous hormones and starch accumulation is still unclear.ResultsAfter spraying fronds with 800 mg/L uniconazole, L. punctata can accumulate starch quickly, with a dry weight starch content of up to 48% after 240 h of growth compared to 15.7% in the control group. Electron microscopy showed that the starch granule content was elevated after uniconazole application. The activities of key enzymes involved in starch synthesis were also significantly increased. Moreover, the expression of regulatory elements of the cytokinin (CK), abscisic acid (ABA) and gibberellin (GA) signaling pathways that are involved in chlorophyll and starch metabolism also changed correspondingly. Importantly, the expression levels of key enzymes involved in starch biosynthesis were up-regulated, while transcript-encoding enzymes involved in starch degradation and other carbohydrate metabolic branches were down-regulated.ConclusionThe increase of endogenous ABA and CK levels positively promoted the activity of ADP-glucose pyrophosphorylase (AGPase) and chlorophyll content, while the decrease in endogenous GA levels inactivated α-amylase. Thus, the alterations of endogenous hormone levels resulted in starch accumulation due to regulation of the expression of genes involved in the starch metabolism pathway.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0245-8) contains supplementary material, which is available to authorized users.

Transcriptome Profiling of the Elongating Internode of Cotton (Gossypium hirsutum L.) Seedlings in Response to Mepiquat Chloride

“…MC-induced increase of CK (trans-zeatin) content was consistent with the up-regulation of CK biosynthesis (IPT3 and CYP735A1) and transport genes (PUP11) in cotton internodes (Figures 5C, 7D, and 8). This correlated well with other studies that other GA biosynthesis inhibitors such as PAC, uniconazole, and Pro-Ca increase CK levels in different plant tissues (Grossmann et al, 1994;Upreti et al, 2013;Liu et al, 2015). Active CKs are degraded mainly by CKX, which can be induced by exogenous CK (6-BA) owing to feedback mechanisms (Kieber and Schaller, 2018;Ni et al, 2018).…”

“…PAC could reduce GA content, but increased cytokinin (CK) and abscisic acid (ABA) content in the buds and leaves of mango (Upreti et al, 2013). Uniconazole and Pro-Ca application yielded similar results in duckweed (Landoltia punctata) (Liu et al, 2015) and in the shoots of wheat and oilseed rape, respectively (Grossmann et al, 1994). Uniconazole has been reported to inhibit brassinosteroid (BR) biosynthesis in Pisum sativum (Yokota et al, 1991).…”

“…PAC affected the expression of many hormonerelated genes in Jatropha (Seesangboon et al, 2018) and Agapanthus praecox (Zhang et al, 2015). The expression of genes related to GA, CK, and ABA was altered by uniconazole in duckweed (Liu et al, 2015). However, whether the biosynthesis and signaling of these hormones are directly affected by plant growth retardants or not is unknown.…”

Dynamic of accumulation and redistribution of various carbohydrate forms and nitrogen in organs of tomatoes under treatment with retardants

“…Спостерігали зменшення площі листкової поверхні та підвищення продуктивності культури (Yan et al, 2015). За дії цього ж ретарданту відбувалося збільшення вмісту крохмалю у рослин Landoltia punctata (Liu et al, 2014).…”

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].…”