FT-IR characterization of pollen biochemistry was analyzed to detect possible connection with the viability (by staining with potassium iodide, 25%) and the germination capacity (on solid nutrient medium), in 15
The
African violet (
In order to identify chemical compounds of different biological materials such pollen [
This paper is a comprehensive study of pollen belonging to 15 African violet genotypes. The lack of consistent and relevant data on bioactive elements of
In order to investigate the chemical composition, viability, and germination capacity, pollen was collected in October from the mature anthers of 15 genotypes of
The morphology of
Code | Genotype | Flower colour |
Brief description [ |
---|---|---|---|
S1 |
|
Deep pink 52B | Single flower, medium green foliage |
S2 |
|
Strong red 53B | Single flower, light green foliage |
S3 |
|
Light purple RHS 77D | Semidouble flower, medium green foliage |
S4 |
|
Light pink 39D | Single flower, dark green foliage |
S5 |
|
Signal violet RHS 77D and greenish white 155C | Single flower, dark blue with a white eye on the middle of corolla, medium green foliage |
S6 |
|
Strong red 53B | Single flower, dark green, quilted foliage |
S7 |
|
Light pink 39D | Single flower, white with pink thumbprint on each petal, and dark green foliage |
S8 |
|
Strong violet RHS 90B | Violet single flower, dark green foliage |
S9 |
|
Greenish white 155C | Double flower, light green foliage |
S10 |
|
Strong violet RHS 90B | Single flower, light green girl-type foliage |
S11 |
|
Light pink 39D | Single flower, dark green foliage |
S12 |
|
Strong red 39D | Semidouble flowers, with a slightly ruffled edge; foliage is dark green |
S13 |
|
Strong violet RHS 90B | Double flower, long stalk, and light green foliage |
S14 |
|
Strong red 39D | Semidouble, bright red, dark green foliage |
S15 |
|
Light blue RHS 104D | Single small flowers, light green foliage |
The research of spectral differentiation in pollen grain biochemistry was conducted in the Raman and IR Spectrometry Laboratory, at the UASMVCN, with the FT/IR-4100 spectrometer (Jasco Analytical Instruments, Easton, USA), with a spectral region between 4000 and 350 cm−1 and a resolution of 4 cm−1. The pellet mode was chosen, in which the pollen samples (3 mg) were mixed with 200 mg of potassium bromide and then compressed into tablets (Specac, IR accessory for producing pills) [
The FT-IR absorption bands of the spectral region 1,800–800 cm−1 (4 cm−1 resolution) of
The FT-IR spectral bands assignment in the 1,800–800 cm−1 zone (4 cm−1 resolution) in the
The molecular vibrations in pollen samples at 1,800–800 cm−1 region (4 cm−1 resolution) in
The Spectra Manager software package was used for scanning samples. The data were processed using ORIGIN 8.5 Pro software.
In order to determine the viability test, the collected anthers were put in a Carnoy solution for 2 hours, after which they were washed in 80% ethyl alcohol. The determination of pollen viability was obtained by staining with potassium iodide (25%). Pollen viability was obtained by staining with potassium iodide (25%). The brown pollen was considered viable, and the colourless one unviable [
The germination and pollen viability were evaluated in accordance with the methodologies described by Gudadhe and Dhoran [
Data on viability and germination of
Fourier transform infrared spectroscopy (FT-IR) is modern analytical method, allowing rapid examination of the relative biochemical compositions of pollen or other biological material [
Previous studies have shown that there are significant differences at the level of the biochemical composition of pollen belonging to related species; however there are few studies on the biochemical differences of pollen between genotypes of the same genus [
The spectral bands assignment using the FT-IR method, in the case of
Spectral zone | Peak frequency cm−1 | Chemical bonds |
---|---|---|
1,800−1,500 cm−1 | ≈1,730 cm−1 | C=O stretch (lipids, triglycerides, and alkyl-esters) |
1,660–1,666 cm−1 | C=O stretch (amide I-proteins) | |
1,608 cm−1 | COO− antisymmetric stretch (acidic group of polygalacturonic acids) | |
1,540–1,550 cm−1 | N–H deformation; C–N stretch (amide II, proteins and lignin) | |
≈1,514 cm−1 | C=C–C (approximation of aromatic ring bonding) (sporopollenin) | |
|
||
1,400−1,000 cm−1 | 1,416–1,418 cm−1 | COO− symmetric stretch (acidic group of polygalacturonic acids) |
1,440−1,450 cm−1 | CH2, CH3 deformation (acidic group of polygalacturonic acids) | |
1,318−1,321 cm−1 | (C–C, C–O) (acetylenic compounds) | |
1,255−1,257 cm−1 | C–O–H deformation; C=O stretching of phenolics (lipids and triglycerides, pectins, and carbohydrate molecule) | |
1,104–1,106 cm−1 | C–OH skeletal; C–O–C sugar ring (carbohydrate molecule) | |
1,050–1,055 cm−1 | C–O–C stretch; C–OH stretch; C–OH deformation; C–O–C deformation, pyranose, and furanose ring (carbohydrate molecule) | |
|
||
900−800 cm−1 | ≈920 cm−1 | C–H ( |
830−836 cm−1 | C–O–C ( |
For
In the spectral region of 1,500–900 cm−1 a prominent band around the value of 1,400 cm−1 (COO− stretch and CH2 and CH3 deformation) appeared, which is attributed to the presence of lipids and triglycerides, observed by Mularczyk-Oliwa et al. [
For the
The spectral band at 1,608 cm−1 (COO− antisymmetric stretch) was more visible in S8 and S15 genotypes, while in S3 it appears as a shoulder and can be associated with the vibration of polygalacturonic acids. The absorption band of 1,517 cm−1 was found in all genotypes from this group of plants, being correlated to the presence of aromatic rings from sporopollenin [
Genotypes S13 and S15 presented strong vibrations around the value of 1,318 cm−1 (C–O skeletal), attributed to the existence of acetylenic compounds, as reported by Coates [
In the
The presence of aromatic rings in sporopollenin is visibly delimited around the value of 1,515 cm−1 in all genotypes [
The carbohydrate band is presented around 1,055–836 cm−1 through C–O–C stretch, C–OH stretch, C–OH deformation, C–O–C deformation, pyranose and furanose ring, and
The most important bioactive elements were present in all the 15
Pollen quality analyzed through the viability perspective and germination capacity can offer important information for breeders, geneticists, and growers [
The highest percentage of viability was recorded in S3 (94.32%), distinguishing itself by the rich content of carbohydrates (Figures
Percentage of pollen viability in 15 genotypes of
For evaluation of the maximum germination potential and the proper development of the pollen tube, the most quick, simple, and complete method is
Several studies show that this process can be influenced by exogenous factors, composition of the germination environment, and the harvesting conditions [
The highest germination percentage was recorded in S8 (74.16%), followed by S15 (65.46%) and S4 (56.46%). This can be correlated with the high lipid content, an essential element in the storage of nutrients and energy necessary for germination. Lipid bodies are used as cytological markers so as to monitor the vital processes of pollen grains [
The germination percentage of the pollen grains in
The
The IR spectroscopy results show that the structural and nutritional elements of pollen are present in all analyzed genotypes. The detailed interpretation of spectral bands shows that the spectral intensity of various bioactive components substantially differs from one genotype to another within the same genus. The data obtained in this study allow for the rapid expansion of the standardized FT-IR spectra and can serve as a starting point for the identification, classification, and biochemical characterization of pollen, results confirmed by Zimmermann and Kohler [
Genotypes S3, S4, S5, S8, S9, and S11 can be recommended as potential genitors in breeding for viability and germination purposes. The genotypic behaviour in viability and germination process probably depends on the biochemical components and the connection between them. Research in this sector should continue so as to better highlight the contribution of each element in the evolution of these biological processes, by obtaining quantitative data.
The results obtained based on the research and investigations are important in the global research programs which aim to build and introduce new genotypes of ornamental plants to be competitive in the international ornamental’s assortment.
The authors declare that there is no conflict of interests regarding the publication of this paper.
This paper was published under the frame of European Social Fund, Human Resources Development Operational Programme 2007–2013, Project no. POSDRU/159/1.5/S/132765.