Identification of a cold tolerant mutant in seashore paspalum (Paspalum vaginatum)

Abstract

Seashore paspalum (Paspalum vaginatum Swartz) is a commonly used warm-season turfgrass with superior salt tolerance. Low temperature is one of the major abiotic stresses limiting its growth and plantation regions. A protocol for ethyl methane sulphonate (EMS) induced mutations from embryogenic callus and selection of seashore paspalum mutant line with enhanced cold tolerance was established in the study. Treatment of embryogenic callus with 5 h of 0.8% EMS resulted in an approximate 50% survival rate of callus, which was used for inducing mutations from embryogenic callus of seashore paspalum. One mutant line (A6) with enhanced cold tolerance was selected and identified from about 10,000 regenerated plantlets. A6 had lower TEL50 (the temperature resulted in 50% electrolyte leakage) and higher survival rate than its wild type (WT) plants after 7 days of cold acclimation. Antioxidant defense system was responsive to low temperature in both genotypes, while higher CAT activity was maintained in A6 than in WT after 3 days of cold treatment. Among four DREB1/CBF genes induced by cold treatment, higher levels of DREB1A, DREB1D, DREB1E transcripts were observed in A6 than in WT. Free amino acids concentrations in response to cold treatment also showed difference between A6 and WT. The results suggest that the response of DREB1/CBFs expression, CAT activity, and free amino acids concentrations to cold is differentially altered in A6 compared with WT, which is associated with the enhanced cold tolerance in A6. A mutant line with enhanced cold tolerance was selected by EMS mutagenesis in seashore paspalum. It had higher catalase activity and DREB1/CBFs transcripts with altered free amino acids than WT.