Studies On Tissue Culture And Transgene Of Several Turfgrasses

Turfgrasses are playing a more and more important role in our daily life. Tissueculture and plantlet regeneration of four turfgrasses, commoncentipedegrass[Eremochloa ophiuroides (Munro.)Hack.], tall fescue ( FestucaarundinaceaSchreb. ) , bermudagrass (Cynodondactylonvar. ) and perennial ryegrass(Lolium perenne L. ) were studied in the second part of thesis. The genetictransformation systems for common centipedegrass and tall fescue were established,and Barus gene and Chilu gene were transferred into common centipedegrassand tall fescue respectively by agrobacterium tumefaciesediated or biolisticbombardment, and many transgenic plants resistant to herbicide and fungi diseasehad been acquired.Establishment and optimization of tissue culture systems of turfgrasses would lay a solid foundation for traditional and transgenic breeding of turfgrasses. The major results studied in the part were abstracted as follows:1) According to selection of explants, excised mature seederived embryos as explants had higher induction and differentiation frequency of calli compared to seeds as explants in tall fescue, and in common centipedegrass, epicotyl from seeds buds germinated on induction medium containing low 2,4 ?D concentration was the best explant for callus induction and differentiation compared with other explants such as mature seeds.2) Tall fescue, common centipedegrass and ryegrass required different optimum 2,4 - D concentrations for callus induction, and the optimum 2,4 ?D concentration is 3. 5 mg/L and 6. 5 mg/L , respectively in common centipedegrass with the highest induction frequency 67.5% and in ryegrass with 85. 6%. Three cultivars of tall fescue also required different optimum 2,4 - D concentrations for callus induction, with 2.5 mg/L, 4.0 mg/L and 4.5 mg/L respectively in SAFari, Barleduc and Firewar II. There were similar effects on callus induction of SAFari, Barleduc and Firewar II between IAA and 2, 4, but more preminent with 2, 4. In addition, 0. 5 mg/L 6-BA decreased to an extent rate of callus induction in tall fescue,3) ABA could suppress to an extent germination of seeds and decrease callus induction frequency in tall fescue and bermudagrass, however, 4. 0 mg/L ABA for tall fescue and 0. 5 mg/L ABA for bermudagrass increased somatic embryogenisis frequency from appearance. Callus with different apparent characteristics had different indogenous GA3, ZT, IAA, ABA and IBA content and proportions.4) Mannitol, sucrose and PEG6000 could increase osmotic pressure of induction medium and affect induction frequency and quality of callus. 1% mannitol,3% sucrose and 1% PEG6000 could improve quality and increase somaticembryogenisis frequency, and 5% or higher PEG6000 caused cell drought , and decreased callus induction frequency , finally caused it to be brown and dead.5) There were different calli induction frequency on different basal mediums in tall fescue and common centipedegrass. There were the highest induction frequency (90%)on N6 medium and the lowest (65%) on MS in tall fescue, and highest(30.7%)and lowest(20%) in common centipedegrass. In addition, categories and concentrations of gelling agents had different effects on callus induction frequency and quality in tall fescue and common centipedegrass.6) Callus with different characteristic had different cell shapes and somatic embryogenisis. Bicellular proembryos, multicellular proembryos, globular embryo id, pear haped embryoid , heart haped embryoid and plumule could be observed by microscopy in embryogeni-c callus of tall fescue and common centipedegrass. Callus cells in bermudagrass showed characteristics of non -embryogenic cells with big shape and big vacuoles,but no nucleolus .7) There was different differentiation vigor in tall fescue and common centipedegrass with different characteristics, and high differentiation frequency with yellow hard granalous callus and low differentiation frequency with light white loose callus. The suitable concentrations of CoC...