| Wheat is the main food crop in China.Aphids have always been one of the main reasons that endanger wheat production and affect the increase of yield.Using chemical pesticides to control aphids is easy to pollute the environment,and long-term use will lead to aphid resistance.Therefore,cultivating wheat varieties with high aphid resistance has important and long-term practical value.In this thesis,plant genetic engineering technology combined with conventional cross breeding methods was used to cultivate new aphid resistant wheat accessions.The main research contents and results are as follows:According to the transgenic raw materials obtained in the early stage,specific and appropriate primers and amplification system are designed.Using touchdown PCR,the specific target gene fragment can be amplified under the annealing temperature of 67℃.The progeny obtained from the forward and backward cross experiments were identified by PCR,and the "No.5" transgenic wheat with cytoplasmic inheritance and good aphid resistance was selected as the base material.The "No.5" transgenic wheat was selected as the base material.Taking "No.5" material as non-recurrent parent and "No.88" material as recurrent parent,35 backcross offspring with aphid resistance gene PPA were screened through backcross breeding and PCR analysis.From 35 backcross progenies,12 highly resistant strains were screened by aphid resistance identification.From 35 testcross progenies,combined with PCR analysis,7 materials with cytoplasmic inheritance were selected.Based on the above results,three strains with high aphid resistance and cytoplasmic inheritance of PPA were screened.The material numbers were 88-3-2,88-3-4 and 88-7-5 respectively.The aphid inhibition rates were as high as 67.89%,72.15% and 63.03% respectively.The above materials can be used as new accessions for wheat aphid resistance breeding.At present,the commonly used routine identification methods of aphid resistance at seedling stage have many problems,such as obvious fluctuation of results and great difference between different experimental batches.This paper improves and optimizes the technical system of laboratory aphid resistance identification,so as to obtain more stable and reliable aphid resistance identification results.Using this system,10 d,20 d and 30 d of aphid-resistant offspring of the 11 "Shi 4185" transgenic offspring with cytoplasmic inheritance identified and screened in the previous study were selected,and 4 were selected with high degree of homogeneity and aphid resistance.The materials with good effect,the material numbers are: a4-1,a4-13,b2-2 and b2-5,among them,the inhibition rate of a4-1is as high as 51.22% at the 30 th day.The aphid resistance of 20 transgenic offspring of "Shi4185" with cytoplasmic inheritance identified and screened in the previous study was identified for 10 days.According to the aphid resistance identification results,7 high aphid resistance strains were screened and obtained.The material numbers were a4-12,a1-10,b2-4,a3-18,a4-8,a2-3 and A2-2 respectively.The population density inhibition rate of a4-12 at the 10 th day was 89.24%. |
