title: A Novel Two-Step Method for Screening Shade Tolerant Mutant Plants via Dwarfism.
abstract: When subjected to shade, plants undergo rapid shoot elongation, which often makes them more prone to disease and mechanical damage. Shade-tolerant plants can be difficult to breed; however, they offer a substantial benefit over other varieties in low-light areas. Although perennial ryegrass (Lolium perenneL.) is a popular species of turf grasses because of their good appearance and fast establishment, the plant normally does not perform well under shade conditions. It has been reported that, in turfgrass, induced dwarfism can enhance shade tolerance. Here we describe a two-step procedure for isolating shade tolerant mutants of perennial ryegrass by first screening for dominant dwarf mutants, and then screening dwarf plants for shade tolerance. The two-step screening process to isolate shade tolerant mutants can be done efficiently with limited space at early seedling stages, which enables quick and efficient isolation of shade tolerant mutants, and thus facilitates development of shade tolerant new cultivars of turfgrasses. Using the method, we isolated 136 dwarf mutants from 300,000 mutagenized seeds, with 65 being shade tolerant (0.022%). When screened directly for shade tolerance, we recovered only four mutants from a population of 150,000 (0.003%) mutagenized seeds. One shade tolerant mutant,shadow-1, was characterized in detail. In addition to dwarfism,shadow-1and its sexual progeny displayed high degrees of tolerance to both natural and artificial shade. We showed that endogenous gibberellin (GA) content inshadow-1was higher than wild-type controls, andshadow-1was also partially GA insensitive. Our novel, simple and effective two-step screening method should be applicable to breeding shade tolerant cultivars of turfgrasses, ground covers, and other economically important crop plants that can be used under canopies of existing vegetation to increase productivity per unit area of land.
authors.affiliation: Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT USA.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Katin-Grazzini
authors.affiliation: Department of Crop Science, Michigan State University, East Lansing, MI USA.
authors.forename: Sanalkumar
authors.initials: S
authors.lastname: Krishnan
authors.affiliation: Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT USA.
authors.forename: Chandra
authors.initials: C
authors.lastname: Thammina
authors.affiliation: Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CTUSA; Department of Floriculture, Ornamental Horticulture and Landscape Gardening, Faculty of Agriculture, Alexandria University, AlexandriaEgypt.
authors.forename: Rania
authors.initials: R
authors.lastname: El-Tanbouly
authors.affiliation: Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT USA.
authors.forename: Huseyin
authors.initials: H
authors.lastname: Yer
authors.affiliation: Department of Crop Science, Michigan State University, East Lansing, MI USA.
authors.forename: Emily
authors.initials: E
authors.lastname: Merewitz
authors.affiliation: Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT USA.
authors.forename: Karl
authors.initials: K
authors.lastname: Guillard
authors.affiliation: Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT USA.
authors.forename: John
authors.initials: J
authors.lastname: Inguagiato
authors.affiliation: Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: McAvoy
authors.affiliation: Appalachian Fruit Research Station, United States Department of Agriculture, Agricultural Research Service, Kearneysville, WV USA.
authors.forename: Zongrang
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Li
keywords: dwarfism; gibberellins; mutation breeding; screening method; shade tolerance