The Research Of The Create Of Sweet Potato Hairy Roots Induced By Agrobacterium Rhizogenes And Its Application

Sweet potato[Ipomoea.batatas(L.)Lam] which is an important food,feedstuff and industrial crop,which is useful for the human body against cancer,cancer care and so on,and has long been confirmed in home and abroad,has been considered the best human food in the twenty-first century.Nematode disease of sweet potato in China which has become one of the three serious diseases,caused by potato rotted nematodes(Ditylenchus destructor),has increased the most serious potato disease in the north in recent years.To better qontrol the happening and harm of nematode diseases,it is essential to understand the living habits of plant-parasitic nematodes, physiological and biochemical characteristics, genetic characteristics and control mechanism. Therefore,it is important to establish a culture system for the nematodes and gain lots of the same groups as research objects. This paper focussing on the establishing of the system of sterile plant nematodes cultured by hariy roots induced by Agrobacterium rhizogenes,researched the resistance or infection relationship between nematodes and host plants,in order to set up a new technology to study the relationship between nematodes and host plants in the level of cell.Main findings are as follows:(1) It was optimized on conditions of hariy roots of sweet potato Xushu18 induced by Agrobacterium rhizogenes A4.Experiment was arranged by L₉(3⁴) orthogonal design, and repeated three times. And rol genes were checked in Xushu18 and their hairy roots by PCR check. The results showed that the highest induced rates of hairy roots were gained in culture medium MSJ for infection time of 20min by stems of sweet potato Xushu18, and the best concentration of Carbencillin was 1.0mg/l, and they were really hairy roots of Xushu18 induced by Agrobacterium rhizogenes A4 by PCR check. This method indicated that hairy roots were induced reliably with traits of roots generation of brawny, fast-growing and branchy.(2) The system of Ditylenchus destructor reproduced monoxenically on Agrobacterium rhizogenes transformed root cultures between sweetpotato Xushu18 and carrot Tianhong 2 were established. The D. destructor's behavior were observed in vitro,and reproduction were investigated. The results showed: D. destructor can develop and reproduce in normal on hairy roots between sweetpotato Xushu18 and carrot Tianhong 2, and the nematode was able to complete its life cycle; the production rate of D. destructor was 2.64 and 50.6 after 4 and 8 weeks on sweetpotato hairy roots, the production rate of D. destructor was 1.7 and 9.9 after 4 and 8 weeks on carrot hairy roots, the production on sweetpotato hairy roots was clearly more than on carrot hairy roots in the same time; using the system, the nematode's behavior could be clear observed through the microscope, it was very useful to study the plant-parasite interaction. Based on the results, The system of reproduction of D. destructor on sweetpotato hairy roots is feasible, and it was better than reproduction of D. destructor on carrot hairy roots.(3) Hariy roots in the experiment still growed rapidly after 6 months with no abnormal phenomena, and were fit for generation easily,no long-term degradation with cultivation. Agrobacterium rhizogenes A4 was used to induce transgenic hairy roots on sweet potato, and to evaluate an in vitro sweet potato hairy root system for investigations of resistance to D. destructor. The results showed: Nematodes were inoculated on hairy roots of sweet potato xushu18, lizhixiang and lu78066 cultivars, evaluation on resistance of sweet potato cultivars to nematode by nematode reproduction on hairy-roots and nematode was observed into the root tissue after 6 weeks. The results showed: the production rate of D. destructor was 8.82,0.76 and 0.70 after 6 weeks on sweetpotato hairy roots xushu18,lizhixiang and lu78066,nematodes were observed into Xushu18 root tissue many place, but lizhixiang and lu78066 root tissue only one place. Xushu18 was susceptible cultivar to nematode, Lizhixiang and Lu78066 were resistance cultivars to nematode. Evaluation on resistance to nematode of Xushu18 and Lu78066 cultivars accorded with natural infection in field, Lizhixiang was out of accord with evalution by natural infection in field. The results of evaluation showed hairy roots induced by A.rhizogenes was a versatile, easy and reproducible system for testing nematode resistance, it will be a new system to evaluate the resistance of sweet potato cultivars to nematode to perfect it.