By visual examination of calli derived from germinating seeds of wheat, oats, rice, proso millet, and pearl millet it has been possible to visually select embryogenic (E) callus which, on transfer to a regeneration medium, forms plants an average of 33 times more frequently than non-embryogenic (NE) callus of equal mass. Embryogenic callus consists of small isodiametric cells averaging 31 μm in diameter; NE callus consists of long tubular cells averaging 52 μm in width and 355 μm in length. Production of E callus is in many cases promoted by media containing 2,4-di- or 2,4,5-trichlorophenoxyacetic acid (2,4-D or 2,4,5-T) plus indole-3-acetic acid or tryptophan+kinetin. Production on NE callus is promoted by media containing 2,4-D or 2,4,5-T alone. As a result of initial experiments to optimize both media for E callus production and media for plant regeneration, callus derived in six passages from an average of 26 seeds could produce about 1,000 regenerated plants.

Motivation: Mass cytometry (CyTOF) is a valuable technology for high-dimensional analysis at the single cell level. Identification of different cell populations is an important task during the data analysis. Many clustering tools can perform this task, however, they are time consuming, often involve a manual step, and lack reproducibility when new data is included in the analysis. Learning cell types from an annotated set of cells solves these problems. However, currently available mass cytometry classifiers are either complex, dependent on prior knowledge of the cell type markers during the learning process, or can only identify canonical cell types. Results: We propose to use a Linear Discriminant Analysis (LDA) classifier to automatically identify cell populations in CyTOF data. LDA shows comparable results with two state-of-the-art algorithms on four benchmark datasets and also outperforms a non-linear classifier such as the k-nearest neighbour classifier. To illustrate its scalability to large datasets with deeply annotated cell subtypes, we apply LDA to a dataset of ~3.5 million cells representing 57 cell types. LDA has high performance on abundant cell types as well as the majority of rare cell types, and provides accurate estimates of cell type frequencies. Further incorporating a rejection option, based on the estimated posterior probabilities, allows LDA to identify cell types that were not encountered during training. Altogether, reproducible prediction of cell type compositions using LDA opens up possibilities to analyse large cohort studies based on mass cytometry data.

Simulated drought tolerance was compared for an NaCI-adapted and a nonadapted cell line of tobacco (Niotiana tabacum var. Samsum) to determine the relationship of salt and drought tolerances. The osmotic adjustment and growth of these two lines was followed when cultured on solid media which contained isosmotic concentrations of NaCL KC1, polyethylene glycol (PEG) or dextran. One line was adapted to growth on 130 millmolar NaCI, but the other was not.The (9,21). The NaCl-adapted cell line was grown 10 months in suspension on 130 mm NaCl plus medium E. Medium E contained Linsmaier and Skoog solutes, 0.1% (w/v) each of yeast and malt extracts, 6 ,ug/ml 2,4-D, and 0.5 ug/ml kinetin. The 130 mm NaCl was the highest level of NaCl on which there was continuous growth. The non-adapted cell line was grown 1 year in suspension on medium E (9) and each line was subcultured every 4 to 6 weeks. Cells from both lines were cultured on solid media for four 2-month passages during the experiments reported here.Osmotic Potential. The freezing point depression method was used for the determination of the osmotic potential of the cell sap and agar solidified media (9)

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ABSTRACrCell wall composition of a stable suspension of proso millet (Panicum miliaceum L. cv Abarr) cells is similar to those of tissues and cell suspensions of other graminaceous species. Extraction of hemicelluloses with step-wise increasing concentrations of alkali yields materials that, like those of embryonal cells of maize coleoptiles, comprise mostly glucuronoarabinoxyla, xyloglucan, and small amounts of (1-3),(14)-f- MATERIALS AND METHODS Development of Cell Suspension Cultures. Embryogenic calli of proso millet (Panicum miliaceum L. cv Abarr) were obtained from mature seed (11) and were transferred monthly to LS medium (12) containing 2.5 mg/L 2,4-D, 4% (w/v) sucrose, and 0.8% (w/v) agar. About 1 g ofthe light yellow callus was dispersed into liquid medium in which LS medium was replaced by MS liquid medium (20; commercially packaged by GibCo) and 3% (w/v) sucrose. The suspension was initiated in 20 ml of medium in a 250-ml Erlenmeyer flask on a gyratory shaker at 100 cycles/ min with a 2.5 cm displacement. Ten ml of fresh medium was added three times at 4 to 5 d intervals, and after 2 weeks, 10 ml of the suspension was transferred with a sterile open-end pipet to 10 ml of fresh medium. The process was repeated for three culture cycles until the culture had stabilized. About 0.5 g of the cells was then transferred to 40 ml of fresh medium, and cells were subcultured biweekly. To yield suspensions of smaller cell colonies, a serological pipet was used to transfer cultures. Alternatively, small colonies that accumulated as a 'film' on the flask at or near the surface of the liquid medium were also collected and transferred to fresh medium. Both methods yielded stable cell suspensions that were maintained for 9 months before beginning these experiments. From observations by light microscopy,