Establishments Of System Of Regeneration And Genetic Transformation Of Drought Resistance And Simple Method To Evaluate The Drought Tolerance In Ground Cover Rose (Rosa Hybrida) And Chrysanthemum (Chrysanthemum Morifolium Ramat)

To establish the system to effectively screen and cultivate the germplasm of ornamental ground-cover plants, the ground-cover rose, Rosa hybrida L ' Royal Bassino ' , and ground-cover chrysanthemum, Chrysanthemum morifolium Ramat 'White Snow' , were used to investigate the regeneration and genetic transformation of drought resistance, and to explore the simple method to evaluate the drought tolerance.Ground-cover chrysanthemum 'White Snow' was proliferated well when MS (Murashige & Skoog) media supplemented with 0.2 mg/1 a-Naphtha!ene acetic acid (NAA), 1.0 mg/1 kinetin (KT), 5.0mg/l Gibberellins (GA3), or with 0.1mg/l NAA 2.0 mg/1 KT 5.0mg/l GA3 were used alternately every 40 days. With in vitro leaf as explants, the regeneration rate of 93.8% was achieved in MS media with 2.0mg/l 6-benzoyladenine (6-BA) and 0.2mg/I NAA. In ground-cover rose 'Royal Bassino', with axillary as explants, basal MS media supplemented with 1.5mg/l 6-benzoyladenine (6-BA) and 0.1 mg/1 indole-3-butyric acid (IBA) was as the optimum media with 100% budding; MS plus 0.5mg/l 6-BA and 0.05mg/l IBA was with highest shoot proliferation efficiency of 6.3; and 1/2MS with 0.01 mg/1 IBA was as optimum shoot rooting media with 92% rooting. With petiole of as explants, the shoots were derived from loose callus or through organogenesis, and 57.1% regeneration rate was reached following 2-stage procedure: 1) initial dark induction for 10 days in the media of MS plus 7uM thidiazuron (TDZ); 2) the explants were transferred to regeneration media of MS plus 0.5mg/l 6-BA for 20 days.The binary vector construct pBI-DREBIA containing transcription factor DREBIA gene from Arabidopsis thaliana was introduced into Agrobacterium tumefaciens, LBA4404. The leaf disks of ground cover chrysanthemum 'White Snow' were infected through Agrobacterium-mdiated transformations. The DREBIA gene was integrated into the genome of transgenic plants by PCR and PCR-Southern analysis. During the transformation procedure, a 2-day preculture, a 10-mininute infection with diluted OD600==0.5~0.7 Agrobacterium tumefaciens culture liquid with a ratio of 1/30, and a 2-day co-cultivation could be available to obtain the highest transformation efficiency.Under the conditions of 23℃, RH30% and 10umol.m-2s-1 illumination intensity, the 10-leaf cuttings of 'White Snow' were exposed to dehydrations in air and osmotic adjustments of PEG, respectively. With the prerequisite of determination of wilting index (WI), fresh weight retention rate (FWRR), leaf water potential (LWP), leaf solute osmotic potential (LSOP), malondialdehyde (MDA) content, the activities of superoxide dismutase (SOD) and catalase (CAT) were measured. The main morphological characteristics to describe WI differed in both treatments. Just when the duration of dehydrations in air was less than 8 hours, the cuttings could be recovered in 1/2 Hoagland & Arnon solutions, during which, the changes of FWRR, LWP, MDA content, SOD and CAT activity were related to drought tolerance of the cuttings. With PEG treatment, positive correlation was obtained between the concentrations and several indices, including FWRR, LSOP, MDA content and SODactivity, but no correlation in LWP and CAT activity. Furthermore, with 20% PEG treatment, the cuttings could be recovered normally in the recovery solution within 4h stress, and the changes of FWRR, LSOP, MDA content, SOD activity were related to drought tolerance, but not occurred to LWP and CAT activity. The results above suggested that both dehydrations in air and osmotic adjustments of PEG could be used to evaluate simply the drought tolerance of 'White Snow'; and it differed in their descriptions of WIs and in their available indices of water relations and physiology.