Study On Biological Mechanism Of Heteromorphic Seed Germination Of Cenchrus Longispinus

Tribulus terrestris(Cenchrus longispinus)is the most dangerous invasive invasive weed in northern China.It has seriously affected the ecological safety and animal husbandry development of north grassland.Cenchrus longispinus grass spread,the alien seeds for reproduction is fundamental to the maintenance of population reproduction,crack Heteromorphic seed of Cenchrus longispinus germination of biological mechanisms,can provide technical guidance for regulation of different seed germination period,then for Cenchrus longispinus grass of centralized control and eradicate completely provide technical reserves.In this study,the differences of morphological structure,endogenous hormone content and molecular transcription levels in germination process(drying,imbibition,whitening,budding)of heteromorphic seeds(P type and M type)of Cenchrus longispinus were compared,and the biological mechanism of germination of two heteromorphic seeds of Cenchrus longispinus during different times was analyzed.The main results are as follows:(1)By studying the trend of dimension,1000-grain weight,water content,water absorption and germination rate of heteromorphic seeds(M-type seeds and P-type seeds)of Cenchrus longispinus,it was found that the variation of water absorption was small among the three types of seeds,and there were significant differences in dimension,1000-grain weight,water content,water absorption and germination rate,with spines >M-type seeds > P-type seeds.By scanning electron microscope observation of seed coat and endosperm of M-type and P-type seeds,it was found that the seed coat of P-type seeds was relatively dense,which severely inhibited water absorption,and there were many starch granules in the endosperm of the other two seeds,which were closely arranged.The hydrolyzed pores of starch granules in M-type seeds appeared earlier than that in P-type seeds,and the hydrolyzed pores were larger.(2)The contents of ABA and GA4 endogenous hormones were determined during the germination of two heteromorphic seeds.The results showed that the ABA content of dried P-type seeds was significantly higher than that of M-type seeds,which may lead to stronger dormancy.The content of GA4 in P type seeds was higher than that in M type seeds.(3)Transcriptome sequencing using Illumina platform was performed to obtain all the transcripts of M-and P-type seeds of Cenchrus longispinus at four germination stages.After processing,167237 Unigenes with an average length of 1426 bp were generated,among which 167237 Unigenes were annotated in KEGG,Nr,Swiss Prot,Tr EMBL,KOG,GO and Pfam.By GO enrichment analysis,we found that the function of DEGs was mainly enriched in cell metabolism,while KEGG metabolic pathway analysis showed that the function of DEGs was mainly enriched in metabolic pathway,biosynthesis of secondary metabolites and phenylpropane biosynthesis.(4)Based on transcriptome data,weighted gene co-expression network analysis(WGCNA)was used to screen out two key modules related to the germination of heteromorphic seeds of Cenchrus longispinus.From these modules,SCP,Trxm,NADP,H+-ATPase were excavated.The genes associated with P-type seed germination were CAMTA,NUP,HY5 and HVA22.This study provides the research basis for revealing the biological mechanism of heteromorphic seed germination of Cenchrus longispinus.