The Ferric Hemoglobin Reductase (GmFLbR) Gene Of Soybean Mapping And Preliminary Function Analysis

Hemoglobins exist throughout in animals,plants and microorganisms.In plant,they play critical roles in nitrogen fixation,embryogeny and plant defense responses.In Soybean?Glycine max L.?,ferric hemoglobin reductase?FLbR?reduces ferric loghemoglobin(Lb³⁺)to ferrous hemoglobin(Lb²⁺),which provides a necessary condition for N₂-fixation in nodule.Increase the content of Lb²⁺by improving the activity of GmFlbR and then the nitrogen fixing capacity of the root nodules will increase as well.It will provide more gene resources for the improvement of nitrogen fixation efficiency in soybean and other crops.The main research results of the article are as follows:1.Glycine max Ferric Leghemoglobin Reductase?Gmflbr?mutant was obtained by screening EMS mutagenesis population library.Compared with wild type Williams82,the leaves of the mutant Gmflbr appeared reddish brown spots at the seedling stage.With the growth and development of plant,the number of spots increased gradually and then the leaves turned yellow and fell off.Meanwhile,the number of secondary roots,the number and volume of nodules of mutant Gmflbr decreased significantly.SPAD and net photosynthetic rate decreased with plant growth and development.However,intercellular CO₂ concentration was significantly higher than that of wild type Williams82.2.The expression pattern of GmFLbR in the leaf primordium was analyzed by in situ hybridization.It showed that the gene was expressed in the apical meristem,lateral leaf buds and leaf primordium,indicating that the GmFLbR gene plays an important role in the development of plant leaves.3.CRISPR/Cas9 vector of GmFLbR was constructed and then carried out the genetic transformation in soybean to verify the further gene function and the transgenic plants with the same phenotype are expected.4.EMS mutagenesis population was screened and then located the target gene in6.02-6.55 M on chromosome 18 by mapping of msp6214 mutant F2 population.5.The leaves of the mutant msp6214 was observed and analyzed by paraffin section.It was speculated that a series of changes in the xylem,phloem,phloem fiber and collenchyma led to the adaxial-abaxial polarity disappears,and then resulted in the rewinding phenotype in mutant leaves.