Plantlet Morphogenesis Research Articles

Addition of White Light to Monochromatic Red and Blue Lights Alters the Formation, Growth, and Dormancy of In Vitro-grown Solanum tuberosum L. Microtubers

Monochromatic light and wide-band white light both affect plant growth and development. However, the different effects between monochromatic light and addition white light to monochromatic light on the formation, growth, and dormancy of microtubers have not been fully explored. Therefore, we evaluated these effects using in vitro potatoes grown under pure blue and red lights and a combination of blue light and red light supplemented with white light, respectively. Current results suggested that light spectra influenced microtuber formation, growth, and dormancy by regulating potato plantlet morphogenesis, affecting the synthesis and transportation of photosynthetic metabolites, and altering the accumulation and distribution of biomass in various plant tissues. Monochromatic lights and the combined spectra had differing effects. For instance, monochromatic red light induced the growth of more microtubers, whereas addition white light to red light decreased number but increased weight of microtubers. Meanwhile, monochromatic blue light facilitated tuber growth, whereas addition white light to blue light decreased microtubers weight but increased microtuber number. In addition, composite lights of addition white light to monochromatic red and blue lights both extended the dormancy period, and monochromatic blue light shortened the dormancy period of microtubers >300 mg. Therefore, in microtuber agricultural production, specific light conditions may be applied at different growth stages of in vitro potatoes to increase the number of effective microtubers (>50 mg) and to satisfy storing requirement of seed microtubers.

Monochromatic lights regulate the formation, growth, and dormancy of in vitro-grown Solanum tuberosum L. microtubers

Light quality is a key factor for plant growth. However, the effects of monochromatic lights on the formation, growth, and dormancy of microtubers have not been fully explored. Therefore, the present study was undertaken to evaluate the formation, growth, and dormancy of potato microtubers grown under monochromatic light emitted by light-emitting diodes (LEDs) at six wavelengths: 440 nm blue light (B440), 460 nm blue light (B460), 520 nm green light (G520), 590 nm yellow light (Y590), 620 nm red light (R620), and 660 nm red light (R660). The results suggested that monochromatic light influenced microtuber formation, growth, and dormancy by regulating potato plantlet morphogenesis and enzyme activity, affecting the synthesis, transport, and transformation of photosynthetic metabolites, and altering the accumulation and distribution of biomass in various plant tissues. Y590 did not favor microtuber formation and growth, whereas the other light conditions had differing advantageous effects. For instance, R620 and G520 induced rapid microtuber formation, and both G520 and R660 induced the growth of more microtubers in the middle and late growth stages, respectively. Meanwhile, B440 and B460 facilitated tuber growth and shortened the dormancy period of microtubers >300 mg. Therefore, in potato agricultural production, specific light conditions may be applied at different growth stages of in vitro potato plantlets to shorten the production cycle and increase the number of valid microtubers (microtubers >50 mg).

Pertumbuhan Artemisia vulgaris Secara Kultur Pucuk pada Medium dengan Kandungan Mioinositol dan Ekstrak Khamir

The effects of mioinositol and yeast extract were studied to assess their influence on growth of plantlets of Artemisia vulgaris by shoot culture. The plants regeneration of A. vulgaris were established by removing the nodes of stem and growing in MS multiplication medium with 1 ppm kinetin and 1 ppm NAA for 4 weeks. Shoots were induced for roots on MS treatment medium supplemented with mioinositol and yeast extract, added with 2 ppm IBA. Combination of four levels mioinositol concentration (mg/l): 100, 200, 300, and 400, and four levels of yeast extract concentration (mg/l): 0, 200, 300, and 400 were simultaneously added. Plantlets (2 weeks) were sub cultured on semi liquid MS medium. Plantlets were harvested on 6 weeks old. Measured parameters were fresh weight of plantlets. Data were analyzed using ANOVA followed by HSD test (p=95%). The results showed that the treatment of mioinositol and yeast extract were not significantly influenced on fresh weight of plantlets. Yeast extract was not influenced the growth of plantlets. The growth and morphogenesis of plantlets A. vulgaris were induced in treatment 100 ppm mioinositol, and addition mioinositol were higher than 100 ppm not significantly influenced the growth of plantlets.

Over-expression of KdSOC1 gene affected plantlet morphogenesis in Kalanchoe daigremontiana

Kalanchoe daigremontiana reproduces asexually by producing plantlets along the leaf margin. The aim of this study was to identify the function of the SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 gene in Kalanchoe daigremontiana (KdSOC1) during plantlet morphogenesis. In this study, KdSOC1 gene expression was detected at stem cell niche during in vitro somatic embryogenesis and plantlet morphogenesis. Disrupting endogenous auxin transportation suppressed the KdSOC1 gene response. Knockdown of the KdSOC1 gene caused a defect in cotyledon formation during the early heart stage of somatic embryogenesis. Over-expression (OE) of the KdSOC1 gene resulted in asymmetric plantlet distribution, a reduced number of plantlets, thicker leaves, and thicker vascular fibers. Higher KdPIN1 gene expression and auxin content were found in OE plant compared to those of wild-type plant leaves, which indicated possible KdSOC1 gene role in affecting auxin distribution and accumulation. KdSOC1 gene OE in DR5-GUS Arabidopsis reporting lines resulted in an abnormal auxin response pattern during different stages of somatic embryogenesis. In summary, the KdSOC1 gene OE might alter auxin distribution and accumulation along leaf margin to initiate plantlet formation and distribution, which is crucial for plasticity during plantlet formation under various environmental conditions.

Key KdSOC1 gene expression profiles during plantlet morphogenesis under hormone, photoperiod, and drought treatments.

Kalanchoe daigremontiana utilizes plantlet formation between its zigzag leaf margins as its method of asexual reproduction. In this study, K. daigremontiana SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (KdSOC1), a key intermediate in the transition from vegetative to asexual growth, was cloned. Furthermore, its expression profiles during plantlet formation under different environmental and hormone induction conditions were analyzed. The full-KdSOC1 cDNA sequence length was 1410 bp with 70% shared homology with Carya cathayensis SOC1. The conserved domain search of KdSOC1 showed the absence of I and C domains, which might indicate novel biological functions in K. daigremontiana. The full-KdSOC1 promoter sequence was 1401 bp long and contained multiple-hormone-responsive cis-acting elements. Hormone induction assays showed that gibberellins and salicylic acid mainly regulated KdSOC1 expression. The swift change from low to high KdSOC1 expression levels during long-day induction was accompanied by the rapid emergence of plantlets. Drought stress stimulated KdSOC1 expression in leaves both with and without plantlet formation. Together, the results suggested that KdSOC1 was closely involved in environmental stimulation signal perception and the transduction of K. daigremontiana plantlet formation. Therefore, future identification of KdSOC1 functions might reveal key information that will help elucidate the transition network between embryogenesis and organogenesis during plantlet formation.

Comparative proteomic analysis of off-type and normal phenotype somatic plantlets derived from somatic embryos of Feijoa (Acca sellowiana (O. Berg) Burret)

Morphological disorders in a relevant portion of emerged somatic embryos have been a limiting factor in the true-to-type plantlet formation in Acca sellowiana. In this sense, the present study undertook a comparison between normal phenotype and off-type somatic plantlets protein profiles by means of the 2-D DIGE proteomics approach. Off-type and normal phenotype somatic plantlets obtained at 10 and 20 days conversion were evaluated. Results indicated 12 exclusive spots between normal and off-type plantlets at 10 days conversion, and 17 exclusive spots at 20 days conversion. Also at 20 days conversion, 4 spots were differentially expressed, up- or down-regulated. Two proteins related to carbohydrate metabolism were only expressed in off-types at 10 days conversion, suggesting a more active respiratory pathway. A vicilin-like storage protein was only found in off-types at 20 days conversion, indicating that plantlets may present an abnormality in the mobilization of storage compounds, causing reduced vigor in the development of derived plantlets. The presence of heat shock proteins were only observed during formation of normal phenotype somatic plantlets, indicating that these proteins may be involved in normal morphogenesis of plantlets formed. These new findings shed light on possible genetic or epigenetic mechanisms governing A. sellowiana morphogenesis.

Nitrogen supply and abiotic stress influence canavanine synthesis and the productivity of in vitro regenerated Sutherlandia frutescens microshoots

Environmental stresses can significantly alter the synthesis of both primary and secondary metabolites, resulting in medicinal plants with unpredictable biological activity. Here, in vitro shoot cultures of the medicinal plant Sutherlandia frutescens were used to study the impact of three abiotic stresses (nitrogen availability, drought and salinity), primarily on l-canavanine synthesis. This compound, a non-protein amino acid, is amongst those metabolites linked to the health benefits of Sutherlandia extracts. Nitrogen supplied to microplants positively correlated with canavanine levels, exhibited by a fourfold reduction when nitrates provided were halved. Although the biomass generated was lowered under these conditions, a higher capacity for rooting (52%) in comparison to the controls (37%) became evident. Only a small increase of the canavanine content in microplants growing on 100 mM NaCl medium was detected, indicating that salinity stress was not a major limitation on cavanine production, but that it played more of a role in vitro on plantlet morphogenesis. Similarly, PEG as a supplement had little to no effect on canavanine synthesis. We conclude that a deeper understanding of the nutritional requirements for the agricultural crop management of S. frutescens, which serves the herbal products industry, is needed.

Control of a symmetry-breaking process in the course of the morphogenesis of plantlets of Bidens pilosa L.

A mechanism involving transport, storage and retrieval of a symmetry-breaking message controls the relative growth rate of the cotyledonary buds of plantlets of Bidens pilosa L. The asymmetry was induced by administering a few needle pricks to one cotyledon of each plant. The storage of the symmetry-breaking message was independent of the number of pricks ("all or nothing" process) and irreversible. However, various treatments could render the plants either able to retrieve the stored symmetry-breaking message (in which case, the bud opposite to the pricked cotyledon began to elongate statistically sooner than the one associated with the stimulated cotyledon) or not (both buds then had an equal chance to be the first to start to grow). The retrieval process was also associated with a temporal oscillation. At the level of the whole plants, bud growth was observed only after the removal of apical dominance, and its degree of asymmetry was expressed by use of a parameter g ranging from zero (symmetrical case) to ± 1 (full asymmetry in favor of one of the cotyledonary buds). The highest g-values observed in the present contribution were of the order of 0.5. At the cellular level, the pricking of one cotyledon caused a number of cells, which were within the meristem of the bud associated with the pricked cotyledon and were in cell-cycle phases S or G2, to undergo cellular division and then be blocked in phase G1, whereas the cells of the opposite bud were practically unchanged.

Plantlet Morphogenesis and the Control of Callus Growth and Root Induction of Phaseolus vulgaris with the Addition of a Bean Seed Extract

Summary Exogenous concentrations of bean seed extract prepared from seeds pretreated in aerated water, homogenized in Vei.iky and Martin 's 67-V salt solution, filtered, and added to the culture medium at proper concentrations promote callus proliferation, root morphogenesis, and shoot morphogenesis in leaf expiants of Phaseolus vulgaris var. Bico de Ouro. The activity of the bean seed factor is dependent upon the period of pretreatment in aerated water.