Mapping And Genetic Study On The Single Segment Substitution Early Rice Heading Stage Material

Rice is the staple food to more than 50%population of the world and it is one of the most important food crop to the survival of humans.Rice is the classical model plant in genetic science and genomics research of monocot,and it has important guiding significance to other plants for the similar research.especial cereal crops.Due to in the course of construction of the SSSLs(Single segment substituted lines),the ratio of donor parent genome decreased continuously,and the backcross progeny genetic background tends to the recipient parent by multiple backcrosses.As a result,SSSLs eliminate the interference of the genetic background.Therefore.SSSLs is one of the most ideal material for fine mapping of QTL,it has the characteristics of unicity,stability.and fragments segmentation.From the SSSLs which constructed with D702B(the three lines Inica male sterile line)as the donor parent and 9311(Indica rice cultivar)as the acceptor parent,an early heading material SSSL4-6 was screened in this study.The research of fine mapping of the heading date QTL,the utilization and identification of hybrid superiority,the interaction between the HD gene and Hdl,the interaction between the HD gene and Ghd8 had been done.The main results as follows:1.The heading date of the single segment substitution line SSSL4-6 is about 10 days earlier than control material 9311 under natural long day conditions and natural short day conditions.At the same time,we found that the difference of the plant height,panicle length,1000-grain weight,grain length and grain number per spike was extremely significant,grain density and grain width was significant,yet the number of effective panicles and seed setting rate was not significant by testing the important agronomic traits.2.The heading date QTL was located in the position between SNP1 and SNP2 on chromosome 7 by the 9K-SNP-chip genotyping technology.The length of the segment was about 11.9M.Morever,the SSR markers with polymorphism were used and new Indel markers were developed for the QTL mapping.As a result,the QTL was located between AK35 and AK65,and the physics distance was about 4.8M.Furthermore,RM5436 and AK61 were co-separated with the trait of early heading,so that the early heading gene,named EH7,was closely to the two markers.The result of qRT-PCR to the key heading date gene in SSSL4-6 and 9311 showed that there was almost no expression of Ghd7 in the SSSL4-6.3.SSSL4-6 was hybridized with Y58s,abcgl5,Luo Hong 4A and Lu 56s,respectively.The utilization and identification of hybrid superiority of their F1 showed that their heading date,in addition to Lu 56s/SSSL4-6,was significantly earlier than the F1 of the combination with 9311,and daily yeild significantly increased.In addition,Y58s/SSSL4-6,Luo Hong 4A/SSSL4-6 exhibited heterosis in yield.4.SSSL-/Hd1 and SSSL4-6,SSSL-Ghd8 and SSSL4-6,SSSL-/Hd1,SSSL-Ghd8 and SSSL4-6 were respectively polymerized to 9311 background to research the interaction between EH7,Hdl and Ghd8.The analysis showed that EH7 and Hdl had significantly epistatic effect,as well as Ghd8 and Hdl,while epistatic effect wasn't observed between EH7 and Ghd8.