Protoplast Culture and Plant Regeneration of Winter Wheat (Triticum aestivum L.)

Suspension cultures were established from embryogenic calli derived from cultured anthers of cv. Jinghua No.1 and mature embryos of cv. Youmangbai No. 7, respectively. After being isolated and cultured in WPMI, protoplasts began to form cell walls within 1 day post-isolation, followed by cell division observed between 2–3 days. A division frequency of 22.0% was estimated on the 7th day of culture, and 43.7% on the 14th day. During 10–15 days after the initiation of culture, a large number of cell aggregates emerged, with 0.5–0.8% of plating efficiency. Protoplast-derived calli grew up to lmm or more in diameter when cultured for 4 weeks, and eventually gave rise to green plants through embryogenesis and organogenesis after being transferred to differentiation media. Plant regeneration from protoplasts was already obtained from Jinghua No.l, and protoplast-derived calli from Youmangbai No.7; an experiment on organ differentiation for the latter is under way. A few factors affecting the protoplast cultures were also studied.     

Development of Plantlets from Leaf Protoplast Culture in Brassica juncea var. tsatsi

Protoplast of two mustard cultivars: Brassica juncea var. tsatsi cv. “Quxian Jiaoercai” and “Bangbangcai”, were isolated by enzymolysis from leaf grown in vitro. Protoplasts were suspended in liquid medium and semi-solidified medium with 0.35% low melting point agarose which formed a thin layer floating on the surface of the liquid medium. The first division appeared after 48h in the culture. One week after the original culture, a diluted medium with gradual dicrease of mannitol concentrations (6%→4%→zero) was then added to the culture three times respectively at one week's interval. In this culture method cell division and formation of microcalli were achieved. During the liquid culture of protoplasts, shaking at 20 rpm from time to time was beneficial in the formation of cell colonies and microcalli. Cell colonies developed into calli of approx 0.5—1mm in diameter one month after culture. The plating efficiency, which defined as the percentage of microcatli to numbers of protoplasts, was 0.2%—1%. Shoot regeneration occured when leaf protoplast-derived calli of “Quxian Jiaoercai” were transferred onto the modified MS medium supplemented with BAP 2.0mg/L, KT 1.0mg/L and NAA 0.2mg/L, and those of -'Bangbangcai" were transferred onto the modified MS medium supplemented with BAP 2.0mg/L. Individual shoot was rooted on a rooting medium supplemented with NAA 0.2 or 0.4 mg/L.     

Plant Eegeneration from Protoplasts of Brassica carinata Braun

Protoplasts of Brassica carinata Braun. (accession No. 84A165) were enzymatically isolated from hypocotyls and cotyledons of 3–5 day-old test-tube seedlings or first true leaves taken from greenhouse grown plants at a three-leaf stage. The protoplasts were suspended in a P-B liquid medium solidified with 0.15%–0.3% low melting agarose which formed a thin layer floating on the surface of the liquid medium. The optimum protoplast density was ranging from 5× l03 to 1 × 104/ml. As for the hypocotyl protoplasts, the first division was observed after 48 h in the culture. The division frequency reached 21% and 34% at day 3 and 6 respectively. The initiation of cell division in the case of cotyledon and mesophyll protoplast culture was late, usually at day 5, and the division frequency was also somewhat lower. One week after culture, the cultures were transferred to fluorescent light condition with an intensity of about 1000 lx. A dilution medium DPDK3 was then added and the dilution procedure was repeated at one week interval thereafter. One month after culture, microcalli with 300–500 μm in size were formed. It was also found that in some cases globular embryoid structure protruded on the callus surface. Totally, a 2%–3% plating efficiency was achieved. Shoot regeneration occurred when cotyledon and mesophyll protoplast-derived calli were transferred onto a modified MS medium supplemented with NAA 0.1, BA 3 mg/l. Individual shoots were rooted on a rooting medium supplemented with 0.2 mg/l of IAA. Intact plants with normal morphology were eventually produced.     

Plant Regeneration from Sainfoin(Onobrychis viciaefolia)Protoplasts Derived from Cell Suspensions of Hypocotyl

The protoplasts were isolated from cell suspension cultures of hypocotyl (Onobrychis viciaefolia) cullured continuously for 3–4 months, and were cultured in modified Wguid Ⅴ- KM medium. The first division of the regenerated cell occurred after 24 h. culture. Small calli could be seen with naked eyes in 4 weeks. The calli which were propagated to 2–4 mm long in diameter in the (Ⅳ) medium were transferred onto differentiation medium and shoots appeared after 2–3 weeks. The differentiated shoots formed their roots on 1/2 MS supplamented with NAA 1.0mg/1 and grew into plantlets.     

Plant Regeneration from Protoplast of Trititrigia (Triticum sect. trititrigia Maekey)

Trititrigia is the intergeneric hybrid which is from the hybridization between Triticum durum Desf. and Elytrigia intermedium (Host) Nevski. Protoplasts of Trititrigia were isolated from the embryogenic cell suspension derived from immature inflorescence-induced calli of the hybrid F1. The first division occured 48 hr after plating in modified KM8p culture medium. The plating efficiency of protoplasts was 2% and 12.14% when they were cultured in liquid medium and agarose solidified medium, respectively. Clusters grew vigorously under these conditions. Fresh medium with decreased osmoticum was added 20–30 days after plating. When protoplast-derived calli, 2–4 mm in the size, were transferred step by step to different differentiation media, embryoids, green spots emerged and numerous plants regenerated eventually.     

Cell Wall Regenration During Early Development of Mesophyll Protoplasts of Astragalus melilotoides var. tenuis

The techniques of transmission electron microscopy (TEM), electron microscopy (EM) cytochemical visualization of polysaccharide, cell wall flourescence labelling of cell wall and inhibition of wall formation by coumarin treatment were used to explore the cell wall regeneration and its chemical characteristics in mesophyll protoplasts of Astragalus melilotoides var. tenuis. The results showed that after 24 h in culture a number of protruding vesicles, as well as a small amount of fibrillar component were formed on the surface of protoplasts. On day 3, the amount of fibrils increased significantly. On day 5, regenerated primary wall composed of fibrils and granules were observed, in which polysacchaides were detected as result of the periodic acid-silver methenamine reaction. In addition, after 36 h in culture, the protoplasts tended to coalesce, flourescence staining and coumarin treatment demonstrated that the protoplast adhesion was the result of cell wall formation. Based on these data, problems such as the structure of regenerated wall and its chemical nature, etc. were discussed.     

Culture of Cotyledon and Hypocotyl Protoplasts from True Potato Seedlings in Solanum tuberosum L.

Culture of protoplast using cotyledon and hypocotyl as the donor tissue from true potato seedlings (TPSs) of 3 breeding lines (DTO-33, ND 860-2 and BN 9815-3) of Solanum tuberosum L. was studied. The cotyledons and hypocotyls of TPSs just extended were excised and digested in an enzyme solution containing 1 % cellulase and 0. 5 % macerozyme for 17—20 h after vacuum infiltration of the tissue in the solution. The protoplasts were cultured in an improved liquid medium and transferred onto solid media for callus culture and shoot regeneration. Some factors affecting the efficiency of cotyledon and hypocotyl protoplast culture were studied. The results showed that using the cotyledons and hypocotyls as donor tissues for protoplast isolation and culture in potato, the division frequency of protoplast derived cells was significantly higher than that using the leaves and shoot-tips of the test-tube plantlets: the yield and quality of the protoplast from TPSs cultured under continuous high light intensity (3000 Ix) were much higher than the TPSs cultured under low light intensity (1000 Ix), and no intact protoplast was ever obtained from the TPSs cultured in continuous dark condition. Vacuum infiltration of the cotyledon and hypocotyl segments in enzyme solution before digestion increased protoplast yield. The yield of protoplasts from hypocotyl tissue was significantly higher than from the cotyledon, but there was no significant difference in quality between the protoplast derived from the two tissues. The significance, advantages and shortcomings of using the cotyledons and hypocotyls as the donor tissues for isolation and culture of potato protoplasts are dicussed.     

Plantlet Regeneration from Leaf Protoplast cultures of Japanese Butterbur

Protoplasts were isolated by enzyme digestion from leaf of Japanese butterbur (Petasites japonicus). The enzyme incubation mixture consisted of 4% (W/V)cellulase RS, 2% (W/V) hemicellulase, 1% (W/V) pectinase-dissolved Y-23 and polygalacturonase in a solution of 0. 5 mol/L mannitol at pH 5.7 . In the basic medium of 1/4 MS inorganic salts and 1/2 MS vitamins supplemented with 2 mg/L NAA, 0. 2–0. 5 mg/L BA, 0. 5 mol/L mannitol and 10 g/L sucrose, the cells divided luxuriantly. Regenerated plantlets were formed from callus after bud induction and root initiation.     

Studies on Plant Regeneration from Mesophyll Protoplasts of Solanum tuberosum L.

Protoplasts from potato mesophyll of two strains (Solannum tuberosum L. cv. Xiao Yie Zi x Duo Zi Bia and Solanum tuberosum L. cv. Wu Meng 601) were induced to callus in culture medium of protoplasts. The callus derived from mesophyll protoplasts were transferred to MS medium with 2 mg/l ZT+0.1 mg/L IAA. Shoots regenerated from the callus were detected after 70 days of culture.The shoots which had grown to a height of 2–3 cm were transferred to MS medium with 0.05 mg/L NAA. Roots were coming out in a few days.Complete plantlets were achieved. Stern segments with 1–2 leaves were then transferred to a mixture of sterilized soil and grown, and produced tuber.     

The Effects of Several Exogenous Hormones on Bark Regeneration After Girdling in Eucommia ulmoides

When the exposed surface of the girdled trunk of Eucommia ulmoides Oliv. were daubed with plant hormones, i.e. ethrel, 2,4-D, NAA, GA and NAA+GA respectively in appropriate concentrations, it was found that the 2,4-D, GA and NAA+ GA treated trunks, initiations of phellogen and vascular cambium in callus were earlier than that in control. These trunks treated with ethrel, formation of phellogen alone were earlier. However, initiation of phellogen and differentiation of vascular cambium in the trunk treated with NAA were similar to control.