Analysis Of Phenology Of Stipa Breviflora In Flowering Period Under Warming And Nitrogen Addition By MSAP And CDNA-AFLP

Stipa breviflora belongs to grassy,stipa spp.It is constructive species in desert grassland.The response of flower buds development to climate change is our main purpose in this study.Our experimental area located in the desert grassland of Stipa breviflora in Si Zi Wang Qi,the west of Inner Mongolia.A long-term warming and nitrogen addition and obsering system was set up in the filed,in order to study the the phenophase and spikelet development of Stipa breviflora by using ecological observation,cell biology detection,and molecular biology research techneques,especially make sure the exactly flowering period of growth of Stipa breviflora.Also,we studied the differences of flowering process under different simulated environmental conditions from epigenetics and genetics aspects,to find the DNA methylation and expression differences of flowering phenology of Stipa breviflora.The results are as follows:1.The simulated warming and nitrogen addition condition had a significant impact on the phenological period of Stipa breviflora.The flowering period was in advance significantly;Nitrogen addition delayed fruiting and reproductive duration time,and Warming×Nitrogen addition significantly advanced fruiting time of Stipa breviflora.2.It was the first time that we identified the morphological characteristics of the reproductive system in various flower development periods of Stipa breviflora.The flower bud development period can be divided into eight stages: primary growth stage,elongation stage,single ridge stage,spikelet protuberance stage,glume protuberance stage,floret protuberance stage,pistil and stamen differentiation stage,heading stage.During the time,environmental temperature change,rainfall and other factors will accelerate the flowering process.3.We also found that the process of flowering process of Stipa breviflora has a correlation with the length of its arista of reproductive branches.So we can determine the duration of flowering by measuring arista length.4.The genomic methylation level of Stipa breviflora was higher than that of other normal plants,and with the development of flower,the total methylation level increased during the early stage and decreased after.The methylation pattern analysis showed that the differences exist in both time and space level.During flowering of Stipa breviflora,Warming decreased of methylation level in early flowering stage,which may be the cause of early flowering.Nitrogen addition increased the level of methylation at late flowering stage,which may delay the late flowering stage.Warming × Nitrogen addition induced higher levels of methylation in the flowering process than in the controls,which may delay the flowering process.5.Stipa breviflora have experienced gene expression and gene silencing during flowering.Nitrogen addition inhibited the expression of genes from the early stage to the middle stage.Warming and Warming×Nitrogen addition inhibited the expression of genes in the early and middle stages,and activated the expression of the late genes.