Young Leaf Segments Research Articles

Sugarcane somatic embryogenesis: a scanning electron microscopy study

Spindles of CUBA 87-51 sugarcane were cultured in Murashige and Skoog (MS) basal medium and supplemented with different nutrients. Embryogenic and non-embryogenic callus obtained were comparatively studied by scanning electron microscopy (SEM). Samples of embryogenic callus cultured in regeneration medium (MS without 2.4 dichlorophenoxyacetic acid) were taken at different times for analyzing the sequential process. Distinctive features of two types of callus are shown by SEM: cells organized in embryos are noted in embryogenic callus; while elongated, disorganized cells can be seen in non-embryogenic callus. The characteristics of the embryos during plant regeneration are described. Sugarcane embryoid stages are: globular, globular with lateral notch and scutellum. In this process also appear shoot meristems, leaf and root primordia and finally, true leaves and roots. It is concluded that callus plant regeneration from young leaf segments of sugarcane mainly occur via somatic embryogenesis.

ササユリの試験管内増殖と圃場への移植

Lilium japonicum growing in the experimental field were collected in early May and segments of their scales, leaves and stems of the plants were cultured in vitro on a basal medium consisting of Murashige and Skoog's inorganic salts (1962) supplemented with several organic nutrients. Young leaf-segments were a suitable source for propagation, because they were least contaminated and almost had the same capacity as scale seg- ments for bulblet regeneration. Bulblets were proliferated by culturing whole scales or segments on the basal medium supplemented with 0.1 mg•lliter-1 NAA and 0.01 mg•lliter-1 BA. A cold treatment at 4 °C for more than 12 weeks broke the dormancy of in vitro cultured bulblets. In vitro light conditoin affected both post-in vitro bulblet-rot infection and plant growth in soil. The bulblets incubated in the dark were more sus- ceptible to soil-born organisms than were those incubated in the light. Nearly all the bulblets of more than 400 mg in weight grew into plants with elongated axes (epigeous type plant; ETP). The ETP plantlets required at least 2 years' cultivation before they flowered.

Plant Regeneraton from Callus Cultures of Switchgrass

Regeneration from cells or tissues cultured in vitro is a fundamental requirement for most applications of plant biotechnology. The objective of this study was to develop protocols in which plants could be regenerated with ease and in high numbers from tissue cultures of switchgrass (Panicum virgatum L.). Mature caryopses and young leaf segments of the cultivar Alamo were explanted onto agar solidified Murashige and Skoog medium containing 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 6‐benzylaminopurine (BAP). BAP at 45 μM for mature caryopses and at 5 μA/for leaf explants in combination with 22.5 μM 2,4‐D produced high frequency plantlet regeneration by both organogenesis and somatic embryogenesis. The mode of regeneration was documented by light and scanning electron microscopy. One thousand regenerated plants have been established in the field for observation and evaluation.

Regulation of somatic embryogenesis in long‐term callus cultures of sugarcane (Saccharum officinarum L.)

summaryEmbryogenically competent callus was induced from in vitro grown Saccharum officinarum L. (NCo 310) plantlets by plating young leaf segments on MS basal medium supplemented with 30 μM dicamba for 21 d in darkness, and subsequently transferring to a medium (EFDM) on which embryos could form and develop. Embryogenic response was improved if the EFDM was supplemented with 1 or 5 μM dicamba, casein hydrolysate (1 g 1−1), and 6% maltose or 6–9% corn syrup. Calli maintained their embryogenic competence for up to 16 months under these conditions, and with alternate weekly subcultures on to fresh media containing 20 μM and 30 μM dicamba in the dark, embryogenic callus proliferation could be further increased. Additional improvements in embryogenic competence were optimized to over 40 months when primary callus was alternately precultured at weekly intervals either with 10‐5 M ABA or 5% sorbitol and then transferred to a medium containing 20 or 30 μM dicamba during maintenance. In general, medium plant growth regulator and nutritional cues, especially dicamha concentration, maltose/corn syrup levels and ABA/sorbitol preconditioning, were observed to influence critically both embryogenic callus proliferation and the frequency of somatic embryogenesis. The data are discussed within the context that these treatments can be successfully manipulated to enhance long‐term embryogenic competence and high‐frequency somatic embryogenesis in sugarcane.

Plant regeneration via somatic embryogenesis in ginger

Embryogenic callus cultures of ginger were induced from young leaf segments taken from in vitro shoot cultures. Among the four auxins tested in Murashige & Skoog medium, dicamba at 2.7 μM was most effective in inducing and maintaining embryogenic cultures. Efficient plant regeneration was achieved when embryogenic cultures were transferred to Murashige & Skoog medium containing 8.9 μM benzyladenine. Histological studies revealed various stages of somatic embryogenesis characteristic of the monocot system. The in vitro-raised plants have been established in soil.

In vitro regeneration of Gaillardia pulchella Foug.

Young leaf and internodal stem segments of Gaillardia pulchella, collected from wild species re-established in the greenhouse, were used to initiate callus on Murashige & Skoog medium supplemented with NAA (2.0 mgl−1) and BA (0.4 mgl−1). Callus formed after 10 to 14 days in the dark. Cultures were transferred to fresh medium and placed under lighted conditions where shoot formation occurred approximately 14 to 30 days after initiation. Callus sub-cultured at 14 to 21-day intervals continued to produce primordia for several weeks. Flowers were produced by regenerated shoots maintained on MS medium, but roots did not develop until the plantlets were transferred to soil conditions.

Chlorophyll Fluorescence in Leaves and Cells of Light-Grown Maize ( Zea mays) during Development

A comparison of chlorophyll a fluorescence in segments chosen from different parts of developing maize ( Zea mays L. cv. Golden Bantam) leaf show differences in the relative variable fluorescence intensities of the induction time course at room temperature (Kautsky curves). The low temperature fluorescence emission spectra of intact leaf samples and diluted powder samples which were prepared from different sections of the leaf were measured. Older leaf segments (tip) showed more variable fluorescence and less relative fluorescence of light harvesting chlorophyll a/b-protein complex and of Photosystem II chlorophyll a-protein complex at 77K compared to young leaf segments (base). These results show (1) that the functions of mesophyll and bundle sheath chloroplasts differ during development of the maize leaf (2) that the amount of chlorophyll protein complexes present varies along the maize leaf from base to tip.

Somatic Embryogenesis and Plant Regeneration in Tissue Culture of Echinochloa glabrescens Munro ex Hook. F.

Summary Embryogenic calli which were compact, globular and white in appearance were initiated from young inflorescences and young leaf segments of Echinochloa glabrescens cultured on MS nutrient medium supplemented with 2,4-D and BAP. The induction frequency of embryogenic calli was more than 91% in young inflorescences and 41% in leaf segments. The embryogenic nature was maintained after more than seven months of subculture. The embryoids gave rise to plants on MS regeneration medium. High frequency of green plant regeneration was obtained from both explant cultures of E. glabrescens . However in leaf cultures, albino plants were also observed. Normal green plants grew to maturity, flowered and set seeds. Scanning electron microscope studies revealed that the white, compact, globular callus contained embryoids in various stages of development. Typical bipolar embryoids with scutella, coleoptiles and coleorhizae were observed.

Dynamics of epiphyton on eelgrass (Zostera marina L.) leaves: Relative roles of algal growth, herbivory, and substratum turnover1

Biomass accumulation of epiphytic algae on eelgrass leaves with leaf age was measured during three periods in Roskilde Fjord, Denmark. Epiphyte biomass increased exponentially with leaf age during the first 10–14 d of colonization. On older leaves epiphyton gradually approached a phase with only small changes in biomass. Algal doubling times, calculated from biomass accrual, were between 3.6 and 4.6 d on young leaf segments and increased to more than 14 d on old leaves. When corrected for biomass losses due to invertebrate grazing, algal doubling time was only 5.8 d on old leaves in August 1983. In this period grazing accounted for the bulk of epiphyte biomass losses and was a more important factor than eelgrass leaf renewal in reducing epiphytic load. As a conservative estimate, the epiphyte community contributed 4–5 times more to total aboveground production in the eelgrass bed than was indicated by its biomass contribution.

Propagation of Rhynchostylis retusa BL. (Orchidaceae) by Direct Organogenesis from Leaf Segment Cultures

Young leaf segments from plants growing both in vivo and in vitro were cultured on Mitra et al medium (BM) supplemented variously with auxins (IAA, NAA, 2,4-D), kinetin (KN), GA3, and organic supplements (peptone, urea, casein hydrolysate, and yeast extract). The explants from mature leaves did not show any growth and turned necrotic, while those obtained from juvenile leaves of 6-mo-old plantlets growing in vitro developed protocorm-like bodies (plbs) at their cut surfaces within 4-7 wk, depending on the growth medium. Histological studies revealed their epidermal origin. Formation of plbs subsequently spread all along the explant and suggests a meristematic/generative potential of the epidermal cells in immature leaves. Upon subculture in basal medium, the plbs differentiated into plantlets within 4-5 wk. Although regeneration of plbs was achieved in BM and the auxins or GA3, KN in combination with IAA/NAA in the presence of peptone accelerated their formation.

Clonal Propagation of <i>Phalaenopsis amabilis</i> (L.) BL. cv. 'Golden Horizon' Through <i>In vitro</i> Culture of Leaf Segments

A protocol was established for mass clonal propagation of Phalaenopsis amabilis cv. 'Golden horizon' through in vitro culture of young leaf segments from mature plant. Explants were cultured on half strength Murashige and Skoog (1/2 MS) medium supplemented with N6-benzyladenine (2.0 mg l-1), a-naphthaleneaceetic acid (0.5 mg l-1), 2% (w/v) sucrose, 10% (v/v) coconut water, 2 g l-1 peptone and 1 g l-1 activated charcoal. Each section of explant produced 15 protocorm-like bodies (PLBs) after 12 weeks of culture. When phytohormone was omitted from the medium and 150 mg l-1 L-glutamone was added PLBs were found to be enlarged with leafy shoots and new PLBs were induced from the base of the old ones. Leafy shoots rooted on half strength MS medium supplemented with 2 g l-1 peptone, 2% (w/v) sucrose, 10% (v/v) CW and 1 g l-1 activated charcoal, where 100% explants were developed into plantlets with roots within 8 weeks. The addition of 2.5 g l-1 banana pulp powder enhanced the number and length of roots. Within the first 32 weeks after initiation of culture about 1500 plantlets as well as a huge amount of PLBs were achieved from a single explant section. The plantlets were acclimatized in natural environment. Key words: Phalaenopsis orchid; Leaf segments; Protocorm-like bodies; Micropropagation DOI: http://dx.doi.org/10.3329/bjsir.v46i2.8182 Bangladesh J. Sci. Ind. Res. 46(2), 163-168, 2011