Quality And RAPD Analysis Of Wheat Landrances With Resistance To Head Scab

Wheat scab or Fusarium head blight (HFB), mainly caused by Fusarium graminearum Schwabe, is one of the destructive disease in the world. It not only significantly reduces grain set and grain weight, but also effects grain quality. Severe, mycotoxin contamination of the seeds is harmful to humans and livestock. The physiology of germs, dispersion of pathogen, mechanism of resistance and gene effects have been widely investigated. At present, the utilization of resistant cultivars is the best way to control the disease. Wannian 2, Wumai 1 and Sumai were successfully developed from the progenies of susceptible genetypes. Though resistance to scab of these genetypes have not lost, the agronomic characters are inferior generally, and the high yield and high resistance to scab are contradictory. Lacking of high resistant genetic resources is main reason, which prevent hesitatingly on breeding for scab resistance. Thus, it is urgent for selecting the new resources.To estimate the genetic characters, and the relations between agronomic characters and quality characters, the grain quality and agronomic characters of wheat landrances with high resistance to scab were investigated, and the genetic variations were analyzed by using RAPD marker. 1. The agronomic and quality characters of 22 wheat landrances with high resistance to scab were evaluated. The average of 1000-grain weight was 34.1g. The plant heights ranged from 92cm-170cm. The average of protein content and wet gluten content were 13.49% and 37ml, respectively. On each character, there had some excellent accessions. Furthermore, higher genetic variations had been observed among the agronomic and quality characters. According to GB/T17892-1999, the protein content and the wet gluten content of Zaomangmai, Ning7840, Guangtoumai and Huanglamai were higher than 15.0%; the stability time of Datouhuang exceed 10 minutes. Three varieties, Huanglamai, Baiyuhua and Changmangmai, had good performances on agronomic and quality characters. 2. The relationships among kernel quality and agronomic characters were analyzed using 22 wheatlandrances with high resistance to scab. The results indicate that: (1) The plant height was related to sedimentation value, dry gluten content and wet gluten content at significant level, whereas it had no significant relationships to the other quality characters. Therefore, reducing the plant height and improving the protein content were not conflicted. (2) 1000-grain weight was negative correlated with protein content, wet gluten content and stability time. Though high yield and high quality were generally contradicted, the partial correlation coeffient of protein content and all the yield characters was not significant. These results indicated that it is possible for achieving high yield and high protein the same time. (3) The result, which protein content was not correlated with Farinograph characters at significant level, showed that the good nutritional quality could be increased with good processing quality. (4) The positive correlation between protein content and dry gluten content and wet gluten content was extremely significant. (5) Sedimentation value was significantly correlated with dry gluten content, wet gluten content, protein content and development time. It indicated that sedimentation value was compositive response of quality and amount of gluten, and could be regarded as effective method for selecting cultivars early.3. The genetic variation among 22 wheat landraces with resistant to head scab were estimated by RAPD markers. Fifty-seven arbitrary primers (10-mers) were used for the amplification of the genomic DNA, among which 48 primers (84.21%) could produce 222 bands. Forty-five out of 48 primers (93.75%) were polymorphic, resulting in 178 (80.18%) polymorphic bands. One to 11 polymorphic bands could be amplified from each primer, with an average of 4.6 bands. Some special RAPD bands were only detected in certain wheat landraces. The mean GD based on RAPD makers among the 22 landraces were 0.314, ranging from 0.152 to 0.471. Based on the GD matrix, a dendrogram was constructed using the unweighted pair group method with arithmetic average (UPGMA). All the 22 scab-resistant wheat landraces could be distinguished by RAPD markers. Using the GD value of 0.33 as threshold, the 22 landraces could be clustered into 4 groups. It indicated that the genetic variation of the scab-resistant wheat landraces based on RAPD markers were correlated with the geographical distribution.