Comparison Of Marker-assisted Selection And Phenotype Selection For Resistant To Sheath Blight In Maize

Banded leaf and sheath blight(BLSB) is one of the most harmful diseases with a globally harmfulness.It is also a serious diseases in China especially in the southwest mountain areas of China.Over the years the study on Banded leaf and sheath blight are still in the stage of identification tag,location,mapping and other infrastructure areas,the application in breeding still is very inadequate.That's the reason why the germplasm is insufficient for resistance to the disease.In our research,conventional genetic breeding and modern molecular biology techniques were combined to study on MAS of the disease with a view to provide technical support and material with highly resistance for the breeding.The main results were summaried as follow:1.The disease index of CML270 and 478 is 13.59%and 83.62%,respectively.According to the identification of resistant for BLSB,the maize inbred line CML270 was resistant to maize BLSB,otherwise 478 is highly susceptible.The disease index of F1 was 48.96%, ranged from that of P1 to P2.It showed that there are significant differences in the resistant to BLSB between the two inbred lines.It also verify that CML270 was an inbred lines with high resistance to sheath blight.2.The result of ANOV of each location showed that variance of the 145 families were significant in plant height,ear height and BLSB height.It showed that the resistance of the families were affected by the genotype.The result of combine ANOV of two locations showed that variance of the location were significant in plant height,ear height and height.It showed that the resistance of the families were affected by the locations.The results showed that the resistant of the families were affected by the genotype,envrioment and genotype×envrioment.3.The result of correlation analysis showed that the disease index is significant correlated with the plant height and ear height negatively.It is suggested that the families with higher plant and ear were more resistant to the disease.In breeding application,we can selecet resistant families by selecting the families with higher plant and ear.4.37 high resistance or resistance families were selected according to the results of field experiment in Chengdu.The value of Ear height/height of these families ranged from 0.36 to 0.5.The value of Ear height/height of 26 of the 37 families were bigger than 0.40. 38 high resistance or resistance families were selected according to the results of field experiment in Ya'an.The value of Ear height/height of these families ranged from 0.29 to 0.44.The value of Ear height/height of 31 of the 38 families were bigger than 0.40.It is suggested that it is effective to select the families with high resistance or resistance by using the value of Ear height/height.If the the value of Ear height/height between 0.35 and 0.40 could be used as the selection criterion needs futher study.5.54 families were detected to have the A band(resistance band) with the marker Phi116,25 (46.30%) and 17(31.48%) of these families were identified to resistance family according to the results of field experiment in Chengdu and Ya'an,respectively.59 families were detected to have the A band(resistance band) with the marker Umc1044,21(35.60%)and 15(25.42%) of these families were identified to resistance family according to the results of field experiment in Chengdu and Ya'an,respectively.When both of the 2 markers were combined,only 14(25.93%) and 12(20.34%) families were were identified to resistance family according to the results of field experiment in Chengdu and Ya'an,respectively.It is more accuracy to select by using double-tag than using a single tag.6.The disease-resistant grade level of the individuals of the 12 resistance families were analysis.The majority of the individuals of these families belongs to the 0-3 grade level, the minority of the the individuals of these families belongs to the 5-9 grade level.For instance,a total of 15 individuals of the family 1114-1 were investigated,6,2 and 2 plants belongs to grade level 0,1,and 2,respectively,with a disease-resistant index of 33.33%.A total of 15 individuals of the family 1124-1 were investigated,7,2 and 3 plants belongs to grade level 0,1,and 5,respectively,with a disease-resistant index of 29.62%.A total of 15 individuals of the family 1160-1 were investigated,6,1 and 1 plants belongs to grade level 0,1,and 2,respectively,with a disease-resistant index of 36.30%.It is suggested that the marker assistant selection is reliable by using the markers Phi116 and Umc1044.