In vitro salinity stress tolerance in Urochloa brizantha cultivars

Abstract

Urochloa brizantha is the main forage grass to raise cattle in Brazil, but salt stress can reduce yield. Physiological and molecular mechanisms of adaptation to salt stress remain poorly understood in this species. The objective of this work was to evaluate the responses of three cultivars of U. brizantha to in vitro salt stress. Seeds of three cultivars (Piatã, Marandu, and Xaraés) germinated in filter paper and then transferred to growth on culture media in vitro containing 0, 50, 100, and 200 mg L-1 of sodium chloride (NaCl). Biometric parameters and proline content were determined after 28 days. The data were subjected to analysis of variance and the separation of means was performed by the LSD test (p<0.05). Semi-quantitative expression of the Δ1-pyrroline-5-carboxylate synthase (P5CS1) gene was performed. In all cultivars, an increase of NaCl concentration in the media affected roots and shoots growth. Xaraes cultivar presented the greater biomass reduction while Marandu cultivar was the least affected. Salt stress increased by approximated 0.7 folds transcription of the P5CS1 gene in all cultivars. However, the Marandu cultivar presented a higher proline content and least biomass reduction suggesting a better response to in vitro to salt stress.

Keywords

• Estresse abiótico
• Capim braquiária
• salinidade