| Phalaris minor is a malignant weed that has invaded Yunnan winter crop fields in recent years.The density of soil seed bank determines the damage level of weeds,while the persistence of soil seed determines the density of the seed bank,and the seed life can be used to characterize the persistence of seeds.The life span of soil seeds is affected by soil environmental conditions.It is an ecological and environmental measure to control weeds by controlling seed life through soil environment and controlling soil seed bank without using chemical agents.Temperature and humidity are the most important soil environmental factors.With the progress of agricultural technology,temperature and humidity become controllable environmental factors under certain conditions.In this study,the change of soil temperature and humidity in summer was simulated,and the persistence of P.minor seeds in soil environment was explored through soil storage test,sand culture test and TTC test,and the molecular mechanism of P.minor seeds dormancy release was systematically analyzed by using enzyme activity,metabolome and transcriptome techniques,in order to clarify the conditions and mechanisms of soil temperature and humidity controlling soil seed persistence.To provide the theoretical basis for exploring the precise ecological prevention and control of P.minor.The main research results of this experiment are as follows:(1)The morphological changes of P.minor seeds during the process of dormancy release were observed by scanning electron microscopy,and it was found that the permeability of seed coat was gradually enhanced during the process of dormancy release.(2)Through soil storage test,sand culture germination test and TTC test,it was found that in the storage conditions of 25℃,30℃ and outdoor temperature with soil moisture of 20% and 80%,the seed dormancy degree of P.minor seed decreased gradually with the extension of storage time.In the condition of 80% soil moisture,seeds of P.minor began to germinate at 40 d after storage,and completely eliminated dormancy at 100 d after storage at 25℃ and 80% soil moisture.Therefore,25℃ and80% were the best storage conditions for inducing dormancy release of P.minor seeds.(3)By testing the enzyme activities of P.minor seeds during storage process,it was found that the antioxidant enzyme activities and amylase activities of seeds were proportional to the storage time under the condition of 80% soil moisture,and the enzyme activities were relatively higher in the condition of 80% soil moisture at 25℃.Under the condition of 20% soil moisture,the enzyme activity was lower at 40 d and increased at 80 d.The enzyme activity of 20% soil moisture was significantly higher than that of 80% soil moisture.(4)Metabolomics detection showed that the differential metabolites were enriched in flavonoid biosynthesis,glutathione metabolism and secondary metabolite biosynthesis under 80% soil moisture,and the differential metabolites screened were quercetin,salamine,jasmonone and so on.When the soil moisture was 20%,the differential metabolites were significantly enriched in flavonoid biosynthesis pathway,plant hormone signal transduction,starch and sucrose metabolism pathway,among which the differential metabolites were salvianolic acid A,proanthocyanidin B2,6-methyl flavone,sterol,etc.(5)Transcriptomic studies showed that in 20% soil moisture environment,the differential genes of P.minor were mainly enriched in biosynthesis of secondary metabolites,metabolic pathways and galactose metabolism.Glucose-6-phosphate isomerase(GPI)was significantly up-regulated during the metabolism of starch and sucrose,and glutathione reductase(GSR)was significantly up-regulated during the REDOX process,indicating that in RH20% environment,the main process of starch and sucrose metabolism provides energy for the dormancy removal of small seeds.In80% soil moisture environment,the differential genes of P.minor were mainly enriched in flavonoid biosynthesis,biosynthesis of secondary metabolites,plant hormone signal transduction,and metabolism of starch and sucrose.The expressions of 4-monooxygenase(CYP73A),3-monooxygenase(CYP98A)and Chalcone synthetase(CHS)were significantly up-regulated.GH3,SAUR,ARR-A gene family,IAA was significantly down-regulated,EIN2 was significantly up-regulated;Sucrose phosphate synthetase(SPS)and sucrose synthase(SUS)were significantly down-regulated,and trehalase(TREH)was significantly upregulated,indicating that sucrose synthesis,flavonoid biosynthesis,fatty acid synthesis and ethylene signal transduction were relatively active during the process of mandormancy removal in RH80% environment. |
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