The Molecular Mechnism Of Hd1 That Suppresses Rice Heading Under Long Day Conditions

Rice(Oryza sativa L.)is one of the most important crops in the world.Rice is a typical short-day plants.Heading date of rice was promoted under short day conditions,but was inhibited under long day conditions.Heading date is a key trait for rice cultivars to adapt different cultivation areas and crop seasons.Discovering the regulatory mechanism of rice heading date not only can help people to fully understand the molecular network of plant flowering,but also can provide theoretical guidance for rice breeding and production.The study is based on previous work,includes three parts.The frist part: Eighty one rice materials were collected and their heading date were observed both under long day and short day conditions.The photoperiod sensitivity index was calculated.In addition,exon of the Hd1,Ghd7 and DTH8 genes of these materials were sequenced and the function of alleles were determined.Though correlation analysis,materials with strongly photosensitive were found to carry functional Hd1,Ghd7 and DTH8 alleles,which indicate that the functional alleles of these three genes are necessary for strong photosensitivity.The second part,modified REPSA(REPSA,Restriction Endonuclease Protection Selection and Amplification)methods were used to identify the DNA elements that bind preferentially by different protein combinations of Hd1,Ghd7,DTH8 and HAP5 B.At the same time,DNA degenerate sequence library containing an endonuclease recognition site were prepared.Different protein combinations and degenerate libraries were subjected to binding and enzymatic reactions.Protein-bound DNA molecules were protected,molecules that not bound by the protein were cleaved,and the protected DNA molecules were amplified by PCR and enriched.The PCR products were cloned and sequenced to obtain the conserved DNA sequences bound by different protein combinations.The specific DNA elements for different protein combinations binding were preliminary identified.The third part,to fully explore downstream genes regulated by Hd1,Ghd7 and DTH8,RNA-seq experiments were performed using the strong-photosensitivity material NIL-NHLD1,near-isogenic line material NIL-nhld1,and materials that knocked out Hd1,Ghd7,and DTH8 respectively,in the NIL-NHLD1 background.Several new downstream genes were determined.This study lay foundation to elucidate the molecular mechanism of Hd1,Ghd7,and DTH8 that inhibite rice heading under long-day conditions from both genetic and biochemical perspectives.