| Potato is one of the most important food crops in the world with abundant wild species. Potato bacterial wilt is a destructive plant disease caused by Ralstonia solanacearum, which can make severe yield loss. At present, there are no effective measures to control this disease. Developing resistant cultivars most relies on development of effective method. However, there are no resistant genes found in potato cultivated species, while some wild species containing resistant genes are considered useful but unavailable resoures to enrich potato genetic diversity of bacterial wilt resistance. This study aims to screen resistant germlasms from 3 populations, a parent of which containing bacterial wilt disease resistant genes, also, aims at obtaining high-quality and multi-resistant new potato germplasms via protoplast electrofusion. The main results are as follows:1. Inoculated the race 1 of R. solanacearum to 45 genotypes of 09HE002,51 genotypes of 09HE008,51 genotypes of WD populations, and their parents, studying the disease occurring situation once a week for 5 weeks. After inoculating 3 weeks, the different plants displayed varied tolerance, so the statistics of this week were more appropriate.2. Selected 10,6 and 10 resistant plants from 09HE002,09HE008 and WD populations. Proved by the significant difference analysis, the 26 resistant plants showed significant difference of resistance, which had the similar tolerance with resistant parents. While the selected resistant plants of every population displayed no significant difference of resistance to R. solanacearum, and so did the 3 populations.3. The disease resistant lines exhibited symptoms later than susceptible lines, and rapid increase periods of their average disease indices lagged behind susceptible lines. Based on the analysis, we can conclude that diseased time and disease developing speed between disease resistant lines and susceptible lines are different.4. Suitable fusion parameters and enzymatic hydrolysis conditions were confirmed. All the parents could form callus except cip-dihB3Ci, and parents WT2, AC 142 and SA-46 developed more callus than the parents AC030 and cha, but only the callus of AC 142 and cha regenerated plants. The fusion combainations cip-dihB3C1+AC142, cip-dihB3c1+cha and AC142+cha formed more callus, and regeneranted 23,4 and 2 plants. The combinations AC142+SA-46, WT2+SA-46 and cip-dihB3C1+CW2-1 had no plant differentiation.5. Analysis of ploidy level using flow cytometry showed that, of the 34 regenerated plants from AC 142 calli, there are 26 tetraploids (76.47%),1 hexaploid (2.94%),6 octoploids (17.65%), and 1 mixoploid (2.94%). While of 3 cha regenerants,2 are tetraploids,1 mixoploid.6. Proving by the inoculation of the pathogen in vitro,6 S. chacoense regenerants exhibited no significant difference resistance against race 1 of R. solanacearum comparing with the resistant parent S. chacoense. They showed similar change trends of diseased plant rate and average disease index to S. chacoense. Plant C14-2 displayed stronger tolerance after inoculating 4 weeks. |
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