Three Turf Grasses Induced By EMS And Preliminary Screening And Identification Of Its Mutants

Turf grass is one of the most common landscape plants and is widely used to beautify,improve and protect the urban environment.In recent years,with the intensification of the greenhouse effect and the urban heat island effect,urban high-temperature weather have frequently appeared,and drought problems have also occurred from time to time.High temperature and drought are the main factors that limit the growth of turf grass.These problems have caused the landscape quality of turfgrass to decrease significantly.Therefore,cultivating new varieties of turf grass that are drought tolerance and heat resistance has considerable economic value and social significance.This experiment used perennial ryegrass?Lolium perenne L.?,tall fescue?Festuca arundinacea Schreb.?,and manilagrass?Zoysia matrella?L.?Merr.?as the experimental materials.After EMS mutagenesis,a preliminary screening and identification of the variant strains was performed through traditional morphological analysis,DNA molecular markers and physiological index analysis.This lays the foundation for breeding new turf grass resistant to drought and high temperature.The main findings of this study are as follows:1?Selection of EMS mutagenic conditions for three turf grass species.Using orthogonal experiments with different concentrations of EMS and different time,the EMS concentration gradients were set as follows:0,0.2%,0.4%,0.6%,0.8%,1.0%;the length of time gradients were 0,12,24,36,48,60h.2?Selection of mutagenic seedlings of turf grass.In the three-leaf stage of M₁mutagenic seedlings,after two-week field drought stress treatment,the leaves of some mutagenic seedlings were observed to grow upright without wilting.Among them,there are 10 perennial ryegrass mutagenic plants,15 tall fescue mutagenesis plants,and 12 plants of Zoysia grass matrella.These phenotypically mutagenic seedlings were then numbered and seeds were collected individually.Morphological analysis and SCOT molecular marker analysis were performed on the numbered plants in the M₂ generation trifoliate stage.Morphological analysis revealed that there were some mutagenic seedlings such as the narrowing of leaf surface,the increase of root length and the variation of leaf color.Through the SCOT molecular marker analysis,more specific bands appeared in the SCOT amplification results of the five primers.This result indicates that the genetic diversity of the selected mutagenized plants has also undergone genetic variation.3?Evaluation of drought tolerance and heat resistance.The morphological characteristics of plants are often inextricably linked to their resistance.For example,the narrowing of the leaf surface will reduce the transpiration of the plant,and the long root growth will benefit the plant's absorption of water and inorganic salts.All of these are conducive to the survival of plants in arid and hot climates.Therefore,in this experiment,in the M₂ generation mutants of genetic mutations the narrowing of leaf surface,the increase of root length were selected to evaluate drought tolerance and heat tolerance.Under different treatments,the indicators of three turfgrass mutants and control seedlings were analyzed,including relative conductivity?EL?,Malondialdehyde content?MDA?,chlorophyll content?Chl?,proline content?Pro?and superoxide dismutase activity?SOD?.After data analysis,five drought-tolerant mutants?A-5?B-7?B-9?C-1?C-11?,three heat-resistant mutants?A-8?B-9?C-11?,and one drought-tolerant and heat-resistant mutant?B-9?were finally obtained.