Resistance Of Main Soybean Germplasm To SCN And Management To SCN In Heilongjiang Province.

Soybean originated in China which has 5,000 years' history of soybean cultivation. Generally speaking, soybean cultivation area in China could be normally distinguished the Northen spring soybean area, Huang-Huai-Hai spring - summer soybean area and southern multiple cropping soybean area in China. Soybean Cyst Nematode ( SCN) , Heterodera glycines Ichinohe, is the major diseases of soybean production worldwide. In 1899, Russian scientist Jaczevski found soybean root nematode (Heterodera glycines )in the northeast of China. In 1915 , the disease was firstly reported in Janpan, followed by North Korea (1936), the United States (1954), Egypt (1968), the former Soviet Union (1978), Colombia (1983), Indonesia (1984), Canada, Brazil, Argentina and other countries have reported the occurrence of the nematodes and hazards. In our country, SCN is mainly distributed in the Northeast and Huanghuaihai soybean-producing areas; Heilongjiang, Jilin, Liaoning, Inner Mongolia Autonomous Region in the Northeast soybean-producing area and Shandong, Hebei, Shanxi, Anhui , Henan, Beijing and other provinces and cities in the Huang-Huai-Hai soybean-producing area,especially for the northeastern region. To Heilongjiang Province-China's major northern soybean producing areas, Soybean Cyst Nematode is one of the major diseases in Soybean production. Due to the expansion and extension of time for continuous cropping of soybean, the trend of Soybean Cyst Nematode has spreaded in Heilongjiang Province . At present, 667000 ha of soybean production area suffered with SCN, which is just next to soybean mosaic virus disease as the second-largest. SCN could cause 20% -30% yield reduction normally, 70% -80% yield loss some circumstance and enven worse, production lost on large-scale could be found every year.At present, breeding for disease-resistant varieties is the most widely used prevention and control strategy. This study will be based on the following 6 aspects: enhancing and reducing the damage on the production of soybean in Heilongjiang Province, which brought by soybean cyst nematode and soybean cyst nematode races distribution in Heilongjiang Province; the selecting function for resistance gene to Soybean Cyst Nematode race 3 ; the inheritance of resistance of the main soybean resistance resource to cyst nematode in Heilongjiang Province ; the molecular marker-assisted proof for the resistance of soybean to cyst nematode; ultrastructural changes in the root tip of resistant and susceptable soybean varieties and their progenies after the SCN race 3 infection as well as soybean cyst nematode control system. The study obtained the following process:1. The dominante race of SCN is still race 3 in Heilongjiang Province. But the SCN race 3 changed into race 4 and 14 in Daqing City and Anda City, indicating some changes happened in Heilongjiang. A distribution map of soybean cyst nematode in Heilongjiang was drawn , which made clear the style and distribution of SCN race in Heilongjiang, and provide the basis for soybean breeding for SCN resistance species and the rational distribution of resistant cultivars.2. Soybean cyst nematode (SCN), Heterodera glycines Ichinohe, populations were selected on eight soybean [Glycine max (L.) Merr.] cultivars in SCN race 3 infested soil. This was done to isolate any populations within SCN race 3 field populations which could reproduce successfully on soybean cultivars with SCN race 3 resistance. The populations were selected by growing the soybean cultivars in infested soil for 20 days, then plant roots were cleaned with water and moved to the soil without SCN .After 10 generations of selection, each soil sample was tested for SCN race type. The race designation of the SCN population changed from Race 3 to Race 6 when resistant Kangxian 1, 2, 3, 4, 5 were grown, and from Race 3 to 10, 14 ,15 when Huipizhiheidou ,Peking and Harbinxiaoheidou were grown respectively. The results indicated that the original soybean cyst nematode race groups form the new race after continuous forced selecting on disease-resistant varieties,and changed the original disease-resistant varieties into susceptible varieties. Adopting rotation mode in production is saw as the effective way for maintaining the stability of resistant varieties.3. Genetic analysis of SCN resistance segregation in F₂ of Hefeng 25×Kangxian 4 reciprocal cross shown that the resistance for Kangxian 4 to SCN 3 is controlled by three pairs of recessive alleles. The cytoplasmic effect did not exist in the genetic resistance for soybean to SCN 3. Soybean breeding for multiresistant to SCN is very difficult, but molecular marker-assisted selection is a feasible way which could help to pyramid multigenes from different resistant sources. The results provided genetic base for SCN resistance breeding, and the guidance of SCN resistance breeding.4. Resistant soybean line Ha98-4598 has different allele variation on Satt082 from resistance Kangxian 4,this may be due to two different resistance genes. On the Satt082, Susceptible parent Hefeng 25 and its susceptible progeny material 3(Hefeng 25×Kangxian 4 )F2,material 12(Hefeng 25×Kangxian 4) F3 have the third allele variation locus, maternal effect shows more significant in these two materials. There are two allelic variations existed on the Satt309, the test materials 1,3,5,9,10,11 and 12 have the first allelic variation locus,the test material 2,3,4,7,8 ,11 have the second allelic variation locus, while the test materials 3,11 exist two allelic variation points at the same time. According to the clustering analysis results of 5 allele variation on the two loci, in the Hefeng 25×Kangxian 4 reciprocal cross, Kangxian 4 and resistant offspring 7,8 were in the same class, susceptible parent Hefeng 25 and susceptible material 3 were in another class, so the materials could be separated into resistance and susceptable. Other materials in the progeny are clustered in one class, that is the result of clustering did not separate the susceptible and resistant materials, which may be caused by the small number of primers and failed to fully reveal the genetic variation of test material, and may also for the reason of these progeny materials still existing on SCN3 resistance segregation.5. It is firstly reported that the significant differences of root tip cells ultrastructure changes existed after resistante and susceptible soybean parents were infected by SCN in Heilongjiang Province (resistance: Kangxian 4 and Ha 98-4598;susceptible: Hefeng 25 ).The materials infected by SCN3,which invasive cells and histopathological response to soybean cyst nematode race 3,shown soybean cyst nematode resistance mechanism , Soybean hybrids infected by SCN 3,root tip cells ultrastructure, and the same cross and different crosses individuals existed significant differences . (Hefeng 25×Kangxian 4) F₁ shown that the genetic resistance of soybean to soybean cyst nematode race 3 may mainly be controlled by nucleus and has nothing to do with the cytoplasm. This result is confirmed with the result of SCN inheritance of resistance of (Hefeng25xKangxian4)reciprocal hybrid F₁ which shown no cytoplasmic effect. However, F₁ of (Hefeng 25×Ha 98-4598) shown the trend to parent reaction,which is relative to cytoplasmic effect. The root tip infected by SCN,and formed obvious growing syncytial in infected varieties Hefeng 25,while smaller cells,degradation hollow cytoplasmic degradation,cell membrane and cell wall separation,less cell path;Resistant varieties Kangxian 4 can not provide nutrients to invasive nematode and make them dysplasia or death,this is one of resistance mechanism of soybean to soybean cyst nematode.6. Intergrated and the results of this study and former research conducted by other scientists, the soybean cyst nematode control system is firstly proposed in Heilongjiang Province:(1) Insist on making the soybean cyst nematode and the natural environment as an integral whole part, adopting ecological control, improving soybean growth and ecological environment, enhance the system of irrigating and draining, improving the soil fertility, soil tillage and deep tillage in order to create a good tilth for soybean growth and development, establish crop rotation system to avoid soybean continuous cropping cultivation, so that soybean production into the benign ecological cycle.(2)According to the occurrence rules and characteristics of soybean cyst nematode, due to the soybean high planting density and large area, Pharmacy irrigation is not feasible. Therefore,put the nemacide with fertilizers into soil together when planting so that kill the larvae hatch. In order to reduce the pollution of the environment , a low toxic nemacide or seed coating should be selected, and reduce the dose appropriately. Applying the leave fertilizer (huimanfeng liquid fertilizer et.al)during the early flowering period to ensure healthy growth of soybean plants.(3) Make full use of natural microorganisms, assemble joint control technology, realize the biological control of making bacteria to control pest, artificially increase the number of soybean fields. These bacteria can be parasitic on the cyst, which can not hatch normally. The current applications mainly contain Doufeng No. 1 (thick fungi Verticillium Tanzania) 5kg/667m² and soybean root-holding-bactoria agents. All these can get about 60% of control effect, and reducing soybean yield loss of more than 15%.(4)The selection of SCN-resistant soybean varieties. The application of disease-resistant varieties is one the most of cost-effective measures for controlling the Soybean Cyst Nematode. Our suggestion to Heilongjiang Province: planting kangxian 2, 3, 4 in Anda area in and Nenfeng 15 in Nenjiang area. In resistant breeding for SCN, level resistance and multi-resistant varieties should be used to protect soybean resistance for the future .