Root sample under control condition
(1) The digested total RNA samples were selected, denatured at appropriate temperature, the secondary structure was opened, and the mRNA was enriched with oligo (DT) magnetic beads.    (2) Interrupt reagent is added to the mRNA obtained in the previous step, and the mRNA is fragmented after a certain temperature reaction time.    (3) Add one strand synthesis reaction system prepared in advance to the interrupted mRNA, synthesize one strand cDNA according to the corresponding program on the PCR instrument, prepare two strand synthesis reaction system, and react at an appropriate temperature for a certain time to synthesize two strand cDNA.    (4) The reaction system is prepared, the temperature is suitable for a certain time, the double stranded cDNA end is repaired, and a base is added at the 3 'end to prepare the connector connection reaction system. The temperature is suitable for a certain time to connect the connector with the cDNA.    (5) The PCR reaction system was prepared and the reaction procedure was set to amplify the linked products.    (6) After the PCR product is denatured into a single strand, the cyclization reaction system is prepared, fully mixed and reacted at an appropriate temperature for a certain time to obtain a single strand ring product. After digesting the non cyclized linear DNA molecules, the final library is obtained.    (7) The fragment size and concentration of the library were detected by Agilent 2100 Bioanalyzer.    (8) After the PCR product is denatured into a single strand, the cyclization reaction system is prepared, fully mixed and reacted at an appropriate temperature for a certain time to obtain a single strand ring product. After digesting the non cyclized linear DNA molecules, the final library is obtained.    (9) Single stranded circular DNA molecules replicate through rolling rings to form a DNA nanosphere (DNB) containing more than 200 copies. The obtained DNBS were added into the mesh holes on the chip by using high-density DNA nano chip technology. Sequencing was performed by combined probe anchored polymerization (CPAs).    (10) The library building kit is mgieasy RNA library prep kit for BGI