The role of activated charcoal in plant tissue culture.

Silicon (Si) is the second most abundant element in soil, where its availability to plants can exhilarate to 10% of total dry weight of the plant. Si accumulation/transport occurs in the upward direction, and has been identified in several crop plants. Si application has been known to ameliorate plant growth and development during normal and stressful conditions over past two-decades. During abiotic (salinity, drought, thermal, and heavy metal etc) stress, one of the immediate responses by plant is the generation of reactive oxygen species (ROS), such as singlet oxygen (1O2), superoxide (O2−), hydrogen peroxide (H2O2), and hydroxyl radicals (OH), which cause severe damage to the cell structure, organelles, and functions. To alleviate and repair this damage, plants have developed a complex antioxidant system to maintain homeostasis through non-enzymatic (carotenoids, tocopherols, ascorbate, and glutathione) and enzymatic antioxidants [superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX)]. To this end, the exogenous application of Si has been found to induce stress tolerance by regulating the generation of ROS, reducing electrolytic leakage and malondialdehyde (MDA) contents, and immobilizing and reducing the uptake of toxic ions like Na, under stressful conditions. However, the interaction of Si and plant antioxidant enzyme system remains poorly understood, and further in-depth analyses at the transcriptomic level are needed to understand the mechanisms responsible for the Si-mediated regulation of stress responses.

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Silicon Regulates Antioxidant Activities of Crop Plants under Abiotic-Induced Oxidative Stress: A Review

The objective of this study was to determine the effects of different light-emitting diode (LED) light sources on the growth of upland cotton (Gossypium hirsutum L.) plantlets. Shoot bud apex cuttings of upland cotton (1.0 cm) were transplanted on Murashige and Skoog (MS) basal medium supplemented with 0.1 mg/l 6-benzyladenine (BA) and 0.5 mg/l naphthalene acetic acid (NAA) and cultured in vitro for 45 days. They were exposed to 50 μmol m−2 s−1 photosynthetic photon flux (PPF) and a 12-h photoperiod under six different lights: fluorescent lamp (CON), monochromatic blue LED (B), three blue and red LED mixtures (B:R = 3:1, 1:1, 1:3) and monochromatic red LED (R). The effects of the six light sources on growth and morphogenesis of upland cotton plantlets grown in vitro were investigated. Fresh weight, dry weight, stem length and second internode length were greatest in plantlets cultured under the B:R = 1:1 blue and red LED light, followed by blue LED light, and they were lowest in plantlets cultured under a fluorescent lamp. Chlorophyll content, leaf thickness, palisade tissue length, leaf and stomata area were highest in plantlets cultured under blue LED light. Root activity, sucrose, starch and soluble sugar contents were highest in plantlets cultured under red LED light. Our results showed that larger, healthier plantlets and a greater biomass of upland cotton were produced in the presence of red LED supplemented with a quantity of blue LED light. Blue and red LED (B:R = 1:1) was the most suitable light for the growth of upland cotton plantlets in vitro, and it may be used as alternative light source for an upland cotton culture system.

Effect of light-emitting diodes on growth and morphogenesis of upland cotton (Gossypium hirsutum L.) plantlets in vitro

The subject invention provides novel plants that are not only resistant to 2,4-D and other phenoxy auxin herbicides, but also to aryloxyphenoxypropionate herbicides. Heretofore, there was no expectation or suggestion that a plant with both of these advantageous properties could be produced by the introduction of a single gene. The subject invention also includes plants that produce one or more enzymes of the subject invention alone or “stacked” together with another herbicide resistance gene, preferably a glyphosate resistance gene, so as to provide broader and more robust weed control, increased treatment flexibility, and improved herbicide resistance management options. More specifically, preferred enzymes and genes for use according to the subject invention are referred to herein as AAD (aryloxyalkanoate dioxygenase) genes and proteins. No α-ketoglutarate-dependent dioxygenase enzyme has previously been reported to have the ability to degrade herbicides of different chemical classes and modes of action. This highly novel discovery is the basis of significant herbicide tolerant crop trait opportunities as well as development of selectable marker technology. The subject invention also includes related methods of controlling weeds. The subject invention enables novel combinations of herbicides to be used in new ways. Furthermore, the subject invention provides novel methods of preventing the formation of, and controlling, weeds that are resistant (or naturally more tolerant) to one or more herbicides such as glyphosate.

Herbicide resistance genes

Almost all processes in the life of a plant are directly or indirectly affected by both stresses and phytohormones. Nevertheless, apart from abscisic acid, the role of phytohormones in plant response to water stress is far from being fully elucidated. This review tries to answer the question whether interactions between abscisic acid and some other phytohormones might be important in the regulation of stomatal opening during water stress and subsequent rehydration. Firstly, it describes the changes in the contents of individual endogenous phytohormones during water stress. Then, it deals with the effects of applied phytohormones on stomatal opening, and on transpiration and photosynthetic rates in different plants species. Finally, it focuses on the alleviation or stimulation of absicic acid-induced stomatal closure by application of other phytohormones.

Participation of Phytohormones in the Stomatal Regulation of Gas Exchange During Water Stress

An efficient in vitro plant regeneration system characterized by rapid and continuous production of somatic embryos using leaf and stem explants of abnormal seedling as an explant have been developed in Gossypium hirsutum L. Embryogenic callus and somatic embryos have been obtained directly from the explants of cotton abnormal seedlings. Plant growth regulators influenced the induction of cotton somatic embryogenesis. The optimal medium for direct somatic embryogenesis was modified MS medium supplemented with 0.1 mg l-1 ZT and 2 g l-1 activated carbon. On this medium, an average of 28.0 and 28.1 matured somatic embryos formed from per leaf and stem explants respectively. The highest frequency of somatic embryogenesis was 100%. The somatic embryos were converted into normal plantlets when cultured on modified MS medium supplemented with 0.1 mg l-1 ZT. Upon transfer to soil, plants grew well and appeared normal. Plants could be regenerated within 60–80 days. The system of cotton somatic embryogenesis and plant regeneration described here will facilitate the application of plant tissue culture and genetic engineering on cotton genetic improvement.

Plant regeneration via somatic embryogenesis in cotton

An elite Chinese cotton (Gossypium hirsutum L) cultivar Simian-3 was chosen for tissue culture Callus with a high frequency of somatic embryogenesis, somatic embryos, and regenerative plants was obtained Callus was induced from three types of explants on MSB (MS salts with B, vitamins) medium supplemented with zeatin (ZT) only, but the percentage of callus induction and growth of callus varied It appeared that it was much easier to induce callus from hypocotyl than cotyledon or root explants The concentrations of ZT were critical to the induction and proliferation of callus The optimum ZT concentration for callus induction was 30~50mg/L Two kinds of callus could be identified after 70 days of culture: embryogenic and nonembryogenic callus Embryogenic callus developed into somatic embryos at various stages after 20 days of subculture The capability of embryogenesis depended on the explant types The root was the most responsive explant for production of somatic embryos, the hypocotyl was the next, and the cotyledon was the last Moreover, a low concentration of ZT was advantageous to the induction of embryogenic callus 2, 4-dichlorophenoxyacetic acid (2, 4-D) promoted the proliferation of embryogenic callus, but had a negative effect on the differentiation and germination of somatic embryos Addition of activated charcoal or a proper combination of ZT and 3-indoleacetic acid (IAA) could promote the production, maturation and germination of somatic embryos The best medium for the proliferation of embryogenic callus was ZH medium (Zhang et al, 1996) with 10mg/L 2, 4-D, 05mg/L kinetin (KT) and 05mg/L ZT The best medium for the differentiation and germination of somatic embryos was MSB with 01mg/L ZT and 2g/L activated charcoal An efficient protocol for the production of high frequency somatic embryogenesis and plant regeneration of an elite cotton variety Simian-3 has been developed Complete plants could be regenerated through somatic embryogenesis from hypocotyl, cotyledon and root explants in 3-4 months

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High Frequency Somatic Embryogenesis and Plant Regeneration of an Elite Chinese Cotton Variety

The aminoglycoside antibiotic kanamycin was evaluated for its effects on callus initiation from hypocotyl and cotyledon explants, proliferation of non-embryogenic and embryogenic calli, initiation and development of somatic embryos in cotton (Gossypium hirsutum L.). On this basis, the potential use of kanamycin as a selective agent in genetic transformation with the neomycin phosphotransferase II gene as the selective marker gene was evaluated. Cotton cotyledon and hypocotyl explants, and embryogenic calluses were highly sensitive to kanamycin. Kanamycin at 10 mg/L or higher concentrations reduced callus formation, with complete inhibition at 60 mg/L. Kanamycin inhibited embryogenic callus growth and proliferation, as well as the initiation and development of cotton somatic embryos. The sensitivity of embryogenic callus and somatic embryos to kanamycin was different during the initiation and development stages. Kanamycin was considered as a suitable selective agent for transformed callus formation and growth of non-embryogenic callus. Forty to sixty mg/L was the optimal kanamycin concentration for the induction and proliferation of transformed callus. The concentration of kanamycin must be increased (from 50 to 200 mg/L) for the selection of transformation embryogenic callus and somatic embryos. A scheme for selection of transgenic cotton plants when kanamycin is used as the selection agent is discussed.

Effects of kanamycin on tissue culture and somatic embryogenesis in cotton

Direct induction of cotton somatic embryogenesis

Direct somatic embryogenesis and plant regeneration were achieved in cotton (Gossypium hirsutum L.). On modified MS medium supplemented with 0.10.5 mg/L ZT, embryogenic calli and somatic embryos were directly induced, with the highest percentage induction (11.42%) at 0.1 mg/L ZT. The addition of IAA resulted in decreasing the frequency of direct embryogenesis in cotyledon explants. Although 2,4-D was advantageous to the induction of cotton non-embryogenic callus, embryogenic callus could not be directly obtained on the medium with 2,4-D. Cotyledon explant directly produced embryogenic callus more easily than hypocotyl sections or root segments. Following conversion, the regenerated plants were transferred to soil and showed normal morphological characteristics.

Fang Liu

Papers

Plant regeneration via somatic embryogenesis in cotton

High Frequency Somatic Embryogenesis and Plant Regeneration of an Elite Chinese Cotton Variety

Effects of kanamycin on tissue culture and somatic embryogenesis in cotton

Direct induction of cotton somatic embryogenesis

Direct somatic embryogenesis and plant regeneration from cotton (Gossypium hirsutum L.) explants