Genetic Analysis And Gene Mapping Of A Low-tillering Mutant Lt8601 And Rolling-leaf Mutant Rl8354 In Rice

Tiller and leaf shape are ideal for rice.It is also the two most important agronomic characters that affect rice yield.The tiller number of rice directly affects the number of effective panicles.Then it affects the yield of rice per unit area.Rice leaf is an important place forphotosynthesis of rice and an important source of rice.So the research on the gene of tiller and leaf mutant of rice can provide the theoretical and material basis for the breeding of super-high yield.This research take advantage of ethylmethane sulfonate to mutagenic indica rice variety 676R and 188R,then a few tillering mutant lt8601 and a rolled leaf mutant rl8354 were obtained,and the main contents are summarized as follows:1.Genetic analysis and gene mapping of a low tillering mutant lt8601 in rice.（1）Phenotype and agronomic analysis:lt8601 had no significant phenotypic differences at seedling stage and showed fewer tillering traits at the tillering stage;agronomic traits showed that compared with wild type 676R,the effective panicles per plant,plant height,ear length,per panicle grain number,1000-grain weight,and seed setting rate all showed significant reductions,which were reduced by 78.7%,25.3%,24.5%,29.7%,4.8%,and 6.7%respectively,indicating that the lt8601 mutant gene had a greater effect on plant growth.（2）Genetic analysis:The lt8601 mutant and wild type 676R parents hybridization,all groups to F₁ plants for normal phenotype of tillers,F₂ populations appear normal tillering plants and tillering plants less two types,the statistical analysis results show that there are fewer normal tillering plants and tillering 3:1 in plant,indicated that the traits are controlled by 1 to the recessive nuclear gene.（3）Gene mapping:The lt8601 plants were crossed with the japonica rice variety Nipponbare（NP）to construct a F₂ mapping population.This gene was mapped to the short arm of chromosome 1 between InDel markers RM023 and S2.The genetic distance was2.3 cM and 1.1 cM.The distance is about 1026kb.（4）High throughput sequencing combined with MutMap method for gene mapping and selection of candidate gene results showed:On 12 chromosomes of SNP index scatterplot only SNP locus on chromosome 1 short arm is unimodal distribution and genetic mutations and 1 chromosome chain,is consistent with the results of previous positioning.Further analysis showed that only one locus on chromosome 1 short arm mutation amino acid change,and the site is located in the positioning range,gene encoding an unknown function protein,is a new gene.Therefore,it is speculated that the mutated gene may be the candidate gene that causes the mutant traits of less tiller,and is named lt8601.2.Genetic analysis and gene mapping of rolling leaf mutant rl8354 in rice.（1）Phenotype and agronomic analysis:The rl8354 mutant height,spike length and1000-grain weight were significantly reduced,respectively,18.6%,18.1%and 7.6%respectively.The number of effective panicles,the number of grains per ear and the percentage of seed yield per panicle were 12.3%,3.1%and 4.0%,respectively,compared with the wild type 188R.（2）Genetic analysis:rl8354 mutant and wild type 188R hybrid parents,F₁ group plant for normal leaf type,F₂ group performance normal foliage plants and leaf plant two types,statistical analysis results show that the normal foliage plants and 3:1 in leaf plant,shows the traits are controlled by 1 to the recessive nuclear gene.（3）Gene mapping:The rl8354 mutant and the japonica rice variety Nipponbare（NP）were crossed to construct a F₂ mapping population.The gene was mutated in the short arm of chromosome 2 between the InDel marker H3 and RM6641.The genetic distance was2.3 cM and 5.6 cM.The physical distance was approximately 1189kb.There are no reports of leaf-rolling gene cloning in this region,so it is considered to be a new rice leaf rolling gene,tentatively named rl8354.