Microsporogenesis and Chromosome Numbers in St. Augustinegrass

Interploid St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] hybrids recovered by embryo rescue

“…Artificial propagation is usually vegetative, by stolon cuttings, plugs, or sod. The base chromosome number of St. Augustinegrass is x=9, with diploids (2n=2x=18), triploids (2n=3x=27), and tetraploids (2n=4x=36; Long and Bashaw 1961). Adaptive and morphological variations in St. Augustinegrass are associated with chromosome differences.…”

“…Augustinegrass is a long day plant which makes it easy to manipulate for breeding purposes (Philley et al 1993) because inflorescence initiation can be triggered by artificially extending the photoperiod ) and its florets are relatively large and easy to emasculate (Philley 1994). Ploidy level differences, however, impede the full use of germplasm resources since attempted crosses between plants with different ploidy levels have failed (Long and Bashaw 1961;Busey 1995). It would therefore be desirable to use embryo rescue in order to bridge the ploidy barrier.…”

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

“…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.…”

Impacts of alien grass invasion in coastal seed banks vary amongst native growth forms and dispersal strategies

“…S. secundatum is a perennial, C 4 , stoloniferous, clonal grass (Poaceae), originating from the tropical and subtropical Atlantic coastlines of Africa and the Americas (Sauer 1972). Invasive populations along the eastern Australian coastline have been present since at least the late 1800s (first naturalised specimen collected from Sydney in 1882; Atlas of Living Australia 2013), were most likely derived from a sterile triploid variant (Long and Bashaw 1961) that originated from South Africa (Mullen and Shelton 1996;Sauer 1972), and which spread vegetatively from adventitious stolons. The contribution of newly-developed, commercial fertile cultivars to invasive populations is unknown.…”