Lawn Genetic Improvement Of Genetic Resources, To Explore The Genetic Engineering Of Resistance And Turf-type Tall Fescue Preliminary Study,

Leaf senescence is a highly regulated progress that involves orderly,sequential changes in cellular physiology,biochemistry and gene expression.To screen stay-green mutants from mutagenized Arabidopsis seedlings(Col),mutants showing higher survivability under darkness stress were obtained.One of the mutants,which showed slow growth and premature rosette leaves,were named fnb45(fast neutron b 45).The mutant exhibited a pleiotropic phenotype,including small and thin cotyledons,slight opened hooks in etiolated seedlings,premature rosette leaves, increased apical dominance,decreased seeds.In addition,fnb45 showed delayed seed germination process(8 days) and reduced seed germination rate(42.7%),reduced plant stature,delayed flowering time(77 days) and prolonged lifespan of inflorescences(4 months).Genetic analysis showed the mutation was single recessive and mapped to the middle of chromosomeâ…¢.Fine mapping results showed the mutation was located in a region of 50kb between T16K5 and F3A4-1,a novel locus involved in the regulation of leaf senescence in Arabidopsis.Compared with the wild type,fnb45 was hypersensitive to the exogenous IAA, ABA,high concentration of sugars and PQ.Also there were a 8-fold increase in free IAA level and an 4-fold increase in ABA level in the mutant.The increased endogenous level of IAA in fnb45 plants is probably indirectly affected by the FNB45 mutation.Sucrose metabolism and/or signal transduction were also found being altered,inducing increased levels of anthocyanin.And the activities of SOD and CAT in seedlings were higher than wild type.When checking the expression pattern of several senescence and oxidative stress related genes,we found that ACS4,GD,GS have apparent changes in expression.