Influence of Benzyladenine on Metabolic Changes in Different Rose Tissues

Abstract

Two modern rose varieties, Floribunda and Hybrid Tea, were used to analyze and identify metabolic changes after foliar application with benzyladenine (BA). Volatile organic compounds (VOCs) as metabolites were detected. Two pairs of doses of BA, at 11.16 and 17.87 mg/cm², and 7.17 and 12.26 mg/cm² were applied to the foliage of Hybrid Tea and Floribunda, respectively. Sampling time was optimized and treatment duration was 4 weeks. After treatment, the volatiles from the treated and untreated control roses were extracted using headspace solid-phase microextraction (HS-SPME) technology by three-phase fiber 50/30 µm divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) and analyzed by gas chromatography (GC) coupled with a flame ionization detector (FID), and with mass spectrometry (GC-MS).The results showed that BA and its dose rate led to metabolic changes of treated roses in comparison with untreated controls. The number of VOCs extracted and detected from leaves, stem, rhizosphere and whole plants from the two rose varieties at doses rate of 17.87 and 12.26 mg/cm² were 43, 65, 40 and 68 compounds for each plant material, respectively, for both rose varieties. Whilst the VOCs extracted and detected from both rose varieties for leaves, stem, rhizosphere and whole plants were 38, 61, 34 and 66 compounds for each plant material, respectively. The results demonstrate that some volatiles, such as 4-Heptyn-2-ol, Phenyl methyl ether and 3-Methyl-apopinene, increased with increasing doses of BA; these compounds are aroma chemicals with a very powerful smell. This study shows that BA treatments can have a significant effect on metabolite changes in different rose tissues. This method could be applied to other floriculture plants.

Keywords: VOCs; benzyladenine; headspace solid-phase microextraction (HS-SPME); rose.

Figure 1

Comparison of main peak area of volatile compounds collected in different rose tissues; (A) leaves, (B) stems, (C) rhizosphere, (D) whole plant using different sampling times. 8 weeks, 4 weeks and 2 weeks, bars represent LSD at (p < 0.05) (n = 3).

Figure 2

Effects of different applied concentrations of BA on the extraction efficacy of the total compounds identified from different rose tissues; (A) leaves, (B) stems, (C) whole plant and (D) rhizosphere. Control, 100 mg/L and 200 mg/L of BA; bars represent LSD at (p < 0.05) (n = 3).

Figure 3

Sparse partial least squares discriminant analysis (sPLS-DA) model obtained from the classification of leaves from Floribunda and Hybrid Tea roses samples based on volatile organic compounds (VOCs) according to BA treatments. (A) Score plot of Floribunda and (B) score plot of Hybrid Tea leaves. Red, green and blue colors indicated groups of treatments. L represents Leaves, F represents Floribunda, H represents Hybrid Tea. While C represents control, T1 and T2 represent 100 and 200 mg/L BA, respectively. Three dots in each group mean n = 3 biological replicates.

Figure 4

sPLS-DA model obtained from the classification of stems from Floribunda and Hybrid Tea roses samples based on VOCs according to BA treatments. (A) Score plot of Floribunda and (B) for the Hybrid Tea stems. Red, green and blue colors indicated groups of treatments. S represents Stems, F represents Floribunda, H represents Hybrid Tea. While C represents control, T1 and T2 represent 100 and 200 mg/L BA, respectively. Three dots in each group mean n = 3 biological replicates.

Figure 5

sPLS-DA model obtained from the classification of rhizosphere from Floribunda and Hybrid Tea roses samples based on VOCs according to BA treatments. (A) Score plot of Floribunda and (B) for the Hybrid Tea rhizosphere. Red, green and blue colors indicated groups of treatments. R represents rhizosphere, F represents Floribunda, H represents Hybrid Tea. While C represents control, T1 and T2 represent 100 and 200 mg/L BA, respectively. Three dots in each group mean n = 3 biological replicates.

Figure 6

sPLS-DA model obtained from the classification of whole plants from Floribunda and Hybrid Tea roses samples based on VOCs according to BA treatments. (A) Score plot of Floribunda and (B) for the Hybrid Tea whole plants. Red, green and blue colors indicated groups of treatments. W represents whole plants, F represents Floribunda, H represents Hybrid Tea. While C represents control, T1 and T2 represent 100 and 200 mg/L BA, respectively. Three dots in each group mean n = 3 biological replicates.