Genetic Variation Studies On Geographic Population In Macrosiphum Avenae

Macrosiphum avenae (Homoptera: Aphididae), is one of the most important pests to cereal crop, distributing world-wide. And also it is an efficient vector of several plants virus, what is more important, can spread barley yellow dwarf virus (BYDV). It is the main pest of wheat, especially in dry period, which result in decreasing of yield and quality of wheat.The powerful heterogenic for population differentiation and genetic variation strength its adaptability to variable environment, M.avenae adapted to the nature condition and it also resulted in the heredity variation of M.avenae populations. This study combined the population ecology with molecular biology.Two multilocus genetic markers (RAPD-PCR and SPRS-PCR) as well as two genetic diversity index (gene diversity index and polymorphic rate of loci) and various statistical analysis were used to detect and analysis the geographic population differention of M.avenae, such as heredity instance, likeness index and clustering analyzing. At the same time, the study discussed the problem of using multi-sites markers and statistics analyzing. The main result as follows:1. The size of the gene DNA was calculated to be 21 kbs or so according to themolecular weight Mrker(EcoR1-HindIII digest Lambda DNA).2. Various factor's influence to RAPD-PCR results (different concentration oftemplate genetic DNA) and to SPRS-PCR (annealing temperature of the microsatellite primers) had been explored with experiment, finally the most suitable reaction systems with good stability and repetition had been established .3. Two genetic diversity index (gene diversity index and polymorphic rate ofloci) were using to analysis the RAPD-PCR results, the result showed thatthe DNA diversity among the same geographic population was lower than that of the different populations. The M.avenae population of Xinjiang spring wheat district was an exception, other seven regions showed that southern populations had smaller heredity variation than northern populations. Then the possibility could be drawn that it was concerned with the weather condition of the every locality area and primarily because of results of temperature pressure.4. Based on the analysis of Nei's genetic distance (D), these genetic distanceof eight populations (0.23 ±0.016) were between that of geographic population (0.031± 0.007) and that of subspecies (0.23 ±0.016). The genetic differentiation of M.avenae among in different geographic district was only at the level of population level but had not achieved the subspecies level.5. The analysis of SPRS-PCR with clustering analyzing showed that the genetic difference of the M.avenae populations was obvious. And there were abundant DNA polymorphism among different populations. Xinjiang population, the unique spring wheat district population, was distinct from other 7 winter wheat districts populations, which was evolving to subspecies. There was a structure presented with our country third stairs geography steps degrees distribute. It could explain that climatic variety with the geography of our country and ocean current of air. The genetic variation of inter population in M.avenae populations of same stairs was greatly similar. The reason was M.avenae populations of same stairs grown in similar weather term and our country geography, plus the gene heredity drifting among populations.