| Wheat is one of the most important food crops in China and even the world.Its production and planting area rank first in cereal crops.It is the most important food source for human beings and plays a pivotal role in the production and development of world agriculture.The reputation of world food,which shows its importance to our lives.Sichuan Province belongs to the southwest of winter wheat area.It has a lot of rainy weather all year round,and the air humidity is relatively high.In this area,due to the rainy weather during wheat harvest,it is easy to cause wheat germinating and even pre-harvest sprouting,thus reducing the nutritional and processing quality of wheat.How to control the germination of wheat at maturity is an urgent problem in the current wheat breeding and production in the world,it is also an important target for wheat breeding in southern of China.Chlorophyll is the basic material for photosynthesis of all green plants,while green leaves are the main source of material production.About 69.65%-81.8% of the grain yield is derived from the photosynthetic products are produced by late flowering leaves.Therefore,prolonging the functional period of wheat leaves and promoting the production of more photosynthetic products by leaves,increasing the yield of wheat is the basis for achieving high yield of wheat.Therefore,this study used three recombinant inbred line populations,namely(1):R146×R316(F6:7);(2): Yanzhan 1(YZ1)×J1809(F6:7);(3): Chuannong 17(CN17)×Mianyang 11(MY11)(F8:9).A total of 575 families were planted at the Sichuan Agricultural University's Qionglai wheat breeding base from 2016 to 2017.Identify the germination resistance of the harvest sprouting,study the change of chlorophyll content during grain filling stage and the QTL was initially located.The results are as follows:1.Using the culture seed germination experiment,a total of 404 families of(1)and(2)recombinant inbred lines were identified as pre-harvest sprouting resistance.Calculating the germination index(GI)for two years,the distribution of GI values obtained from 0.207-0.967.We defined the GI value to be less than 0.4 as the anti-shock germination,0.4-0.8 as the medium resistance,and more than 0.8 in the range of easy pre-harvest sprouting.Among the 404 families of the two recombinant inbred lines,there were 63 in total GI values less than 0.4,214 in total between 0.4 and 0.8,and 127 in materials larger than 0.8.2.A total of 404 families of recombinant inbred lines(1)and(2)were analyzed by A-PAGE electrophoresis for seed prolamine analysis to identify the presence of trans-location.Theidentification results showed that among the 233 test materials in the first recombinant inbred line group,there were 63 materials containing 1RS/1BL trans-location and 170 materials containing non 1RS/1BL trans-location.The second material does not contain the 1RS/1BL trans-location.Correlation analysis between 1RS/1BL trans-location and wheat pre-harvest sprouting resistance data was performed.The results showed that 1RS/1BL trans-location was not significantly correlated with GI value.3.SSR molecular markers were used to screen two parents of Chuannong 17 and Mianyang11 in the recombinant inbred line(3),and 191 SSR molecular markers were found to be polymorphic among the parents,thereby constructing CN17×MY11.The genetic map of the recombinant inbred line has a total length of 3203 cm,covering 21 chromosomes of the wheat genome and the average separation distance between the molecular markers is 16.76 cm.4.Taking 171 strains of recombinant inbred lines(3)as materials,fresh leaves were sampled 7 times during grouting,the contents of chlorophyll a and chlorophyll b were determined by micro-plate reader,and then the total chlorophyll content of each material was calculated by formula.For the wheat grain filling period,the content of chlorophyll a,chlorophyll b and total chlorophyll in flag leaves are gradually increasing,and will reach an extreme value about 30 days after flowering.In addition,the 1RS/1BL trans-location does not determine the proportion of the greening lines in the population,and does not cause significant differences in the contents of chlorophyll a,chlorophyll b and total chlorophyll.However,the greening of the strain containing the 1RS/1BL trans-location was slightly longer than that of the non-1RS/1BL trans-location line,that is,the wheat genotype was the main factor to determine the physiological greening of the wheat.5.The QTL positioning analysis uses a complete interval mapping-additive effect parameter:the QTL step spacing is 1.00 cm,and the p-value correlation threshold is 0.001.During the grain filling of wheat,no chlorophyll content-related QTLs with consistent sites were detected at different times.From this,it can be inferred that QTLs controlling the chlorophyll content of wheat are specifically expressed.The QTLs for detecting chlorophyll a content were located on chromosomes 2D,4D and 6D,the QTLs for chlorophyll b content were located on chromosome4 A,and the QTLs for total chlorophyll content were located on chromosomes 1D,2D,4D and 6D.In addition,the QTL locus of chlorophyll a and total chlorophyll content were in the same position on the 2D,4D and 6D chromosomes during the same period of wheat filling. |
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