Identification Of Photo-thermal Response Characteristics And RNA-seq Analysis Of Temperature Response Of Different Types Of Soybean Cultivars

Soybean(Glycine max(L.)Merr.)is known as a short-day plant.This study analyzed the sensitivity of different types of soybean cultivars to the photo-thermal response by sowing in different locations to create temperature differences,and setting different treatments with different day lengths to reveal the photo-thermal response of soybean cultivars.Northeast spring soybean cultivars whose maturity groups(MGs)had been clearly assigned in our previous study were used to analyze their relationship with≥10℃active accumulated temperature(≥10℃AAT)required for the growth period,so as to provide a basis for breeding and layout of cultivars in Northeast China.The transcriptome levels of leaves at the seedling stage under different temperature conditions were analyzed by different temperature treatments in artificial incubators and to explore the expression characteristics of soybean flowering related genes in response to temperature regulation,in order to provide a basis for temperature response mechanism research and temperature adaptation improvement in soybean cultivars.The main results are as follows:1.The photo-thermal response characteristics of different types of soybean cultivars were analyzed,and the test materials were classified into temperature response sensitive,intermediate,and insensitive using temperature response sensitivity(TRS)as identification index.The sensitive soybean cultivars were those with greater variation in flowering period among different temperature treatments.The insensitive soybean cultivars showed less variation in flowering stage among different temperature treatments.The results showed that only Xiaojinhuang1 was a temperature response sensitive cultivar,and 75-158 were a temperature responsive insensitive cultivar under both short day and long day conditions.Long day decreased the temperature response sensitivity of soybean,and increased temperature enhanced the photoperiod response sensitivity.2.A total of 395 northeast spring soybean cultivars with known MGs(MG000-Ⅳ)were used,and the≥10℃AAT required for the growth period of these cultivars was obtained in this study,to further establish the functional relationship between the MGs and the≥10℃AAT required for the growth period(y=254.2x+2105.8).Calculations based on this function showed that there was a significant positive correlation between the MGs of Northeast spring soybean cultivars and the≥10℃AAT required for the growth period(R~2=0.8988).This function is of great theoretical importance to clarify the attribution of MGs of cultivars in the main soybean producing regions of Northeast China,as well as to the exchange of soybean germplasm resources among different regions.3.The photo-thermal insensitive cultivar Heihe27 and sensitive cultivar Nandou12 were selected,treated by artificial incubators set at 25℃(CK),20℃and 30℃,and sampled for RNA-sequencing(RNA-seq).Compared with the CK,at 20℃,Heihe27 obtained 2291 differentially expressed genes(DEGs),of which 1521 were up regulated genes and 770 were down regulated genes.1263 DEGs were obtained for Nandou12,among which 925 were up regulated genes and 338 were down regulated genes.There were 725 DEGs in both cultivars.DEGs of Heihe27 and Nandou12 were partially enriched in the circadian clock plant pathway,and Heihe27 was significantly enriched.Compared with the CK,there were 406 DEGs in Heihe27 at 30℃,among which 245 genes were up regulated and 161 genes were down regulated.There were 471 DEGs in Nandou12,of which 189 genes were up regulated and 282genes were down regulated.There were 112 genes that were differentially expressed in both cultivars.4.After Heihe27 and Nandou12 were treated with different temperatures in an artificial incubator to count the days from emergence to flowering,combined with DEGs obtained from RNA-seq for pathway enrichment analysis and gene annotation information,especially including GO pathway enrichment for the Go term temperature compensation of the circadian clock and KEGG pathway enrichment for the circadian rhythm–plant,we speculated that 20 DEGs might be circadian clock related and related to regulating flowering in response to low temperature.