Gamma-ray Irradiation Induces Useful Morphological Variation in Bermudagrass

Abstract

Bermudagrass, Cynodon dactylon (L.) Pers. is a widely used warm-season turfgrass species in warmer regions of the world. Gamma (ɣ) irradiation has been used to generate useful variations in turfgrass breeding for various morphological traits. The objective of the present study was to measure and determine variations in morphology and turfgrass characteristics of a native drought resistant bermudagrass germplasm irradiated with 70, 90 or 110 Gy using a 60 Co source. The stolons containing a single node were irradiated and immediately planted for regeneration in a greenhouse at the Akdeniz University, Antalya, Turkey. Selected mutants regenerated from the irradiated stolons were clonally propagated and transplanted into plastic pots for further observations of turfgrass characteristics. Survival rates of stolons exposed to 70, 90 and 110 Gy were 76%, 43% and 17% respectively, 6 weeks after treatment. Dosages of 85 and 57 Gy were determined as LD50 and LD20 for the cuttings, respectively. The linear reduction of survival rate with increasing gamma-rays was highly correlated (r 2 =0.99). A total of four mutant lines (0.3 % of the irradiated plants) showed a distinct dwarfed growth habit. Three of these lines were originated from 70 Gy and one from 110 Gy. These mutant lines exhibited more dwarf growth habit, higher shoot density, finer leaf texture than parental genotype. Mutant lines developed in this study can be used for the development of improved bermudagrass cultivars for landscaping and sports turf.

Gamma‐Ray Irradiation Improves Turfgrass Characteristics of St. Augustinegrass

“…The linear reduction of survival rate with increasing gamma‐ray dose was highly correlated, with r 2 values of 0.87 and 0.96 for S1 and S2 genotypes, respectively (data not shown). The result concurs with earlier reports of St. Augustinegrass (Busey, 1980), bermudagrass (Sever Mutlu et al, 2015) and other species of Poaceae family (Krishna et al, 1984; Hase et al, 1999; Zaka et al, 2002). Growth inhibition induced through high‐dose irradiation has been attributed to cell cycle arrest in the G 2 /M phase during somatic cell division and/or to a variety of damages in the entire genome (Preuss and Britt, 2003).…”

“…In total, of the 4301 treated stolon cuttings, 15 morphological mutants (0.35% of the irradiated plants) with a semidwarfed growth habit were identified. Similar to our results, the useful mutant rates were 0.3% in Raleigh St. Augustinegrass (Li et al, 2010) and bermudagrass (Lu et al, 2009; Sever Mutlu et al, 2015). The practical doses for the two genotypes were 40 and 50 Gy.…”

“…On the contrary, the mutant line S1‐100‐3 exhibited two times as many inflorescences as S1 did and a 66% increase in spikelet number. Compared with parental lines, substantial increase (up to threefold) in inflorescence was reported for mutant bermudagrass lines derived from gamma irradiation (Sever Mutlu et al, 2015). Similarly, the mutant lines originating from the S2 genotype exhibited shorter internode length (13–31%), stolon leaf length (16–36%), stolon length (17–34%), plant height (18–40%), and thinner internode diameter (10–27%) (Table 1, Fig.…”

“…Gamma‐ray irradiation has successfully been used to induce useful variations for morphological traits in turfgrass breeding (Busey, 1980; Dickens et al, 1981; Burton, 1985; van Harten, 1998; Hanna and Elsner, 1999). The most frequent mutant characteristic in the irradiated plants is dwarfism (Powell et al, 1974; Burton, 1985; Hanna and Elsner, 1999; Sever Mutlu et al, 2015). Several turfgrass cultivars, including ‘Tifeagle’ bermudagrass [ Cynodon dactylon (L.) Pers.…”

“…. The most frequent mutant characteristic in the irradiated plants is dwarfism (Powell et al, 1974;Burton, 1985;Hanna and Elsner, 1999;Sever Mutlu et al, 2015). Several turfgrass cultivars, including 'Tifeagle' bermudagrass [Cynodon dactylon (L.) Pers.…”