Cytological and Molecular Characterization of Genetic Diversity inStenotaphrum

Abstract

RESEARCH S t. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is widely adapted as a lawn grass in warm, tropical and subtropical regions of the world (Sauer, 1972). The grass is highly resistant to weed infestation (Busey, 2003), grows well in a broad range of soil conditions, and exhibits good performance under shade conditions relative to other warm-season grasses (Busey and David, 1991; Busey et al., 1982b). Broad leaf blades and rapid stolon production allow the grass to form a coarse-textured monostand that is well suited for sod production, home lawns, and commercial landscapes. All these characteristics make St. Augustinegrass a valued turfgrass in the southern United States. The genus Stenotaphrum is comprised of seven species, all indigenous to coastlines from East Africa to islands of the South Pacific (Busey, 1995; Sauer, 1972). Pembagrass [S. dimidatum (L.) Brongn.] is the most closely related species to St. Augustinegrass. Evidence of introgression from this species in some polyploid St. Augustinegrass introductions has been observed (Busey, 1993, 1995). The base chromosome number of S. secundatum is

Development of colchicine‐induced tetraploid St. Augustinegrass (Stenotaphrum secundatum) lines

“… As reported in Milla‐Lewis et al, , whereas flow cytometry identifies Floralawn as a tetraploid, this genotype is an aneuploid with 2 n = 4 x = c.32. …”

“…Corn ( Zea mays L . ‘Bicolor Sweet Frisky F1’) with a known nuclear 2C DNA content of 5.43 pg (Milla‐Lewis et al, ) was used as an internal standard for flow cytometry analysis. Approximately 1 cm 2 of fresh tissue from newly emerging leaves from both the treated plant and corn were placed in 47 mm petri dishes (Millipore SAS,67,120 Molsheim, France) with 600 µl of nuclei extraction buffer (CyStain PI Absolute P, Sysmex Partec GmbH).…”

“…The genus Stenotaphrum comprises seven species with different ploidy levels (Sauer, ). The base chromosome number of S. secundatum is x = 9, with diploids (2 n = 2 x = 18), triploids (2 n = 3 x = 27), tetraploids (2 n = 4 x = 36), hexaploids (2 n = 6 x = 54) and aneuploids (2 n = 28 – 32) being reported (Long & Bashaw, ; Milla‐Lewis, Zuleta, Esbroeck, Quesenberry, & Kenworthy, ). Polyploid genotypes have been found to have greater resistance against several biotic stresses (Yildiz, ) such as lance nematodes ( Hoplolaimus galeatus ) (Giblin‐Davis, Busey, & Center, ), the sting nematode ( Belonolaimus longicaudatus Rau) (Busey, Giblin‐Davis, & Center, ), the St. Augustine Decline Strain of Panicum Mosaic Virus (Horn, Dudeck, & Toler, ), southern chinch bugs ( Blissus insularis Barber) (Busey, ; Busey & Zaenker, ) and Pyricularia oryzae , (Milla‐Lewis et al, ) the causal agent of grey leaf spot.…”

Registration of ‘DALSA 0605’ St. Augustinegrass

“…DALSA 0605 is an interploid hybrid resulting from a cross made between TAES 5382 (Africa polyploid) and Palmetto (diploid) in 2004. TAES 5382 is the program designation given to PI 291594, a germplasm introduction from Zimbabwe, Africa obtained from the USDA–ARS Plant Genetic Resources Conservation Unit, Griffin, GA. PI 291594 was reported by Milla‐Lewis et al (2013) to be triploid, 2 n = 27, which is sterile and incapable of setting fertile seed when crossed with a diploid cultivar. Results of the flow cytometry show that DALSA 0605 has intermediate 2C DNA content (1.24 pg/2C) compared with TAES 5382 (1.78 pg/2C) and Palmetto (1.03 pg/2C).…”

Registration of ‘NUF-76’ St. Augustinegrass

“…NUF‐76 is a fertile diploid (2 n = 2 x = 18) (Nagata and Cherry, 2003; Milla‐Lewis et al, 2013) and fine leaf‐textured St. Augustinegrass cultivar. NUF‐76 relies on rapid growth of lateral stolons to cover ground, differing from Floratam, which covers ground by rapid extension of a primary stolon (Fig.…”