Suspension cultures of Stizolobium hassjoo cells were cultivated in a 7l bioreactor. The growth rate and intracellular L L-DOPA content of the cells using two different turbine impellers were compared. There were distinct differences in growth behavior and L L-DOPA productivity in the range of 100 to 500 rpm for¯at-blade turbine impeller. Disk turbine retarded signi®cantly the cell growth but not so signi®cantly for L L-DOPA production in the range of 200 to 300 rpm. The shear force intensity of the two impellers at various rotational rates was compared with shear force index (SFI), and power input per unit mass and eddy length scale. There was good consistency among the three indexes for shear force intensity. Thus with SFI the shear force intensity of bioreactor can be indirectly estimated. A critical shear stress that may cause sublytic effect in cells was identi®ed for¯at-blade turbine operated at 400 rpm. The common effect between the shear stress and the proton elicitation in the bioreactor was elucidated with a hypothesis of signal transduction by second messenger, H + . Our results suggested that H + transduced the signal to protoplast when S. hassjoo cells were stimulated by shear stress. This resulted in an increase of H + which triggered a similar reaction to the pH control of culture broth and enhanced the L L-DOPA production. List of symbolsRe modi®ed Reynolds number (=D 2 a Nq/l) m a constant P w/kg power input per unit mass P 0 w/kg P for baf¯ed agitated reactor y a constant (Eq. (1)) a a constant (Eq. (2)) b a constant (Eq. (2)) g m eddy length scale l Ns/m 2 viscosity of medium m m 2 /sec kinematic viscosity q kg/m 3 density of medium 1 Introduction In bioreactor for cultivating plant cell, the desired effect of shear stress on the cells is to stimulate the production of secondary metabolites. However, the shear stress may suppress the cell growth [1]. The susceptibility of plant cells to the shear stress varies greatly with cell lines [2, 3]. Meijer [3] found that the Catharanthus roseus cells grew with almost the same growth rate in an agitated reactor at 250 to 1000 rpm. Due to the existence of cell wall, the plant cells can endure tensile strength of 1000±10 000 atm [4].On the contrary, the effect of shear stress on the growth of Cinchona robusta cells was signi®cant. Plant cells can resist a certain strength of shear stress encountered in common bioreactor operation. The total energy required to cause 50% fatality, E 50 for Daucus carota cells is 10 10 J/m 3 [5]. However, the energy required to suppress the activity of the same cells is around 5´10 5 J/m 3 . Plant cells tread a series of metabolic response to alleviate the injury from stress or environmental change. They are able to release a second messenger intracellularly and transduce the signals to protoplast [6]. Plant cells induce the increase of Ca 2+ and the change of pH simultaneously in response to the environmental change [7]. As concentrations of second messengers in the environment change, the metabolic reactions, e.g., activat...

Hybrid breeding employs heterosis, which could potentially improve the yield and quality of a crop. Genomic selection (GS) is a promising approach for the selection of quantitative traits in plant breeding. The main objectives of this study are to (i) propose a GS-based approach to identify potential parental lines and superior hybrid combinations from a breeding population, which is composed of hybrids produced by a half diallel mating design; (ii) develop a software package for users to carry out the proposed approach. An R package, designated EHPGS, was generated to facilitate the employment of the genomic best linear unbiased model considering additive plus dominance marker effects for the hybrid performance evaluation. The R package contains a Bayesian statistical algorithm for calculating genomic estimated breeding value (GEBVs), GEBV-based specific combining ability, general combining ability, mid-parent heterosis, and better-parent heterosis. Three datasets that have been published in literature, including pumpkin (Cucurbita maxima), maize (Zea mays), and wheat (Triticum aestivum L.), were analyzed to illustrate the use of EHPGS.

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