| Plant development and physiology are strongly influenced by the LED light spectrum of the growth environment.The aim of this study was to determine the effects of different LED lights on plant growth in vitro propagation of Gerbera jamesonii and influence of light responsive genes.1.The effects of LED light on in vitro culture of gerbera1.1 Effects of LED light on callus induction of gerbera:This study was to examine the effects of 2,4-dichlorophenoxy acetic acid(2,4-D)and light on callus growth of gerbera.Callus was induced from both petiole and leave explants of gerbera on Murashige and Skoog(MS)medium supplemented with 3%sucrose and 0.5,1.0,1.5 or 2.0 mg/L 2,4-D and placed under white LED light and dark treatments.Callus induction percentage,callus size,callus fresh and dry weights were efficiently higher when petiole was used as explant.MS medium supplemented with 1.5 mg/L 2,4-D showed best results for callus induction with 96.70%.Callus induced under light had larger weight mass.Our results showed that 1.5 mg/L 2,4-D and light proved better for callus growth of gerbera from petiole explant.1.2 Effects of LED light on shoot proliferation of gerbera plantlets:The stem explants were cultured on MS basal medium supplemented with the combination of 2.0 mg/L Benzyl-6-adenine(BA)and 0.1 mg/L naphthalene acetic acid(NAA)for shoot proliferation.Plantlets were placed under light intensities and qualities treatments.In light intensity,treatments were as follows:Low-Flourescent light(L-FL)was at 2.664 lux;High-Flourescent light(H-FL)at 92.5 lux;Low-White LED(L-W)at 2.664 lux and High-White LED(H-W)at 92.5 lux.Light quality consisted of Blue(B)and Red(R)LEDs treatments at 2.664 lux,where the flourescent light was used as control(FL).This study demonstrated that plantlets under B LED and low intensity under L-W lights promoted vigorous growth,as they proved proper plant height,stronger stems and leaves resulted in maximum dry weights.1.3 Effects of LED light on rooting of gerbera:1/2 MS supplemented with 0.5 mg/L NAA was used for rooting medium.Plantlets were placed under light intensities and qualities treatments.High-and low-intensities of fluorescent lamps and white LED at 92.5 lux and 2.664 lux were used.Light quality consisted of B and R LEDs treatments at 2.664 lux,where fluorescent light was used as control(FL).Results indicated that low light intensity was more suitable for rooting and root activities on L-W treatment.Moreover,B LED treatment was the best light for rooting and root activities.2.Effects of LED on physiological and biochemical changesThe stem explants were cultured on MS basal medium supplemented with combination of 2.0 mg/L BA and 0.1 mg/L NAA for shoot proliferation.Plantlets were placed under light qualities and intensities treatments High-and Low-intensities of fluorescent lamps and white LED at 92.5 lux and 2.664 lux were used.Light quality consisted of Blue and Red LEDs treatments at 2.664 lux,where fluorescent light was used as control(FL).Indexes on chlorophyll fluorescence,chlorophyll content,stomatal density and soluble sugars were analyzed.When plantlets were exposed on low light intensity,φPSII,Fv/Fm and qP were highest under L-W.There was a reduction of φPSII,Fv/Fm and qP in plants exposed to R LED treatments.However,B LED was suitable for the increase of φPSII,Fv/Fm and qP.L-W and B were suitable for chlorophyll and soluble sugars synthesis.Smaller number of stomata and larger leaf area which seemed to be an important for leaf stomata opening was obtained under B LED and L-W.3.Gene cloning and bioinformatics analysis of light responsive genes in gerberaThe plantlets under fluorescent light were further used as the materials to carry out cloning of CRY1,CRY2 and PHYA genes by the technique of transcriptome data combined with combined RT-PCR.In this experiment,the complete sequences of target genes were obtained and the length of CRY1,CRY2 and PHYA were 2020 bp,2005 bp and 3763 bp,respectively.The accession numbers were KY968644,KY968645 and KY964410,respectively.Bioinformatics analysis showed that the physical and chemical properties of CRY 1 and CRY2 were similar and had stable proteins.CRY1,CRY2 and PHYA belonged to the transmembrane proteins and they were likely to be in the nucleus,cytoplasm and mitochondria.CRY1 and CRY2 had similar Domain FAD-binding while PHYA belonged to BAES super family.4.Expression of light responsive genes in gerberaThe plantlets under light quantity and quality treatments were further used as the materials to carry out expression levels of CRY1,CRY2 and PHYA genes.In gerbera,the expression of CRY1 and CRY2 were detected in all tested tissues under all light treatments.The relative expression of CRY1 at low light intensity under L-W was higher on leaf,stem and root when compared to other light treatments.L-W obtained highest relative expression on leaf and stem,followed by H-W.In CRY2,L-W obtained highest relative expression on leaf and stem at low light intensity,followed by H-W at high light intensity.On the root,the expression of CRY2 was higher under H-FL.The CRY1 relative expression was highest on leaf,stem and root under B LEDs.On the other hand,the CRY2 gene was found to be highly expressed under B LED under leaf and stem.However,studies on PHYA gene revealed that different LED light on gerbera did not have an impact on this gene expression even though it is photoreceptor for a red light.In this study,it can be concluded that 1.5 mg/L 2,4-D and light proved better for callus growth of gerbera from petiole explant.Again,the results illustrated that LED treatments with best plantlets had shorter plant height,stronger stems and leaves with maximum dry weight.There was relationship between physiological,biochemical traits and relative expression of CRY1 and CRY2 when plantlets placed under different LED lights treatments.In overall observation,B LED and L-W at low intensity had better developed plantlets and can be recommended to be used in future for maximizing the economic efficiency of gerbera production. |
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