Development of a New Cold-Tolerant Maize(Zea mays L.)Germplasm Using the ICE1 Gene from Arabidopsis thaliana

To develop cold-tolerant maize germplasms and identify the activation of INDUCER OF CRT/DRE-BINDING FACTOR EXPRESSION(ICE1)expression in response to cold stress,RT-PCR was used to amplify the complete open reading frame sequence of the ICE1 gene and construct the plant expression vector pCAMBIA3301-ICE1-Bar.Immature maize embryos and calli were transformed with the recombinant vector using Agrobacterium tumefaciens-mediated transformations.From the regenerated plantlets,three T1 lines were screened and identi-fied by PCR.A Southern blot analysis showed that a single copy of the ICE1 gene was integrated into the maize(Zea mays L.)genomes of the three T1 generations.Under low temperature-stress conditions(4°C),the relative conductivity levels decreased by 27.51%–31.44%,the proline concentrations increased by 12.50%–17.50%,the malondialdehyde concentrations decreased by 16.78%–18.37%,and the peroxidase activities increased by 19.60%–22.89%in the T1 lines compared with those of the control.A real-time quantitative PCR analysis showed that the ICE1 gene was ectopically expressed in the roots,stems,and leaves of the T1 lines.ICE1 positively regulates the expression of the CBF genes in response to cold stress.Thus,this study showed the successful transformation of maize with the ICE1 gene,resulting in the generation of a new maize germplasm that had increased tolerance to cold stress.

A continuum method for granular collapse with μ(I)-rheology-based dynamic earth pressure coefficient

In this paper,a continuum model with dynamic earth pressure coefficient is established to describe the granular slump process by introducingμ(I)rheology.This rheology is adopted to quantify the normal stresses in our proposed model rather than shear stresses in classical models.The constitutive laws of different depth-averaged continuum approaches including the hydrodynamic,Savage–Hutter and proposed models are comparatively investigated in terms of the rheological effects on the spread of a granular column.The simulation results indicate that the proposed dynamic model captures some significant features during granular slump on inclined planes with different inclination angles(for example,the runout distance,runout time,and final profile).The proposed model can also reproduce the inner static sided axisymmetric region observed in tests when the granular column's initial aspect ratio(ratio of height to radii)is small.