Lethal dose 50 of NaCl and ethyl methanesulfonate in jalape?o pepper (Capsicum annuum L.) seedlings and tolerance to salinity

Soil salinity is a factor affecting crop production and yield. An estimated 74% of agricultural soils are saline, a problem that could be aggravated due to climate change. Our goal was to determine the lethal dose 50 (LD50) of NaCl and ethyl methanesulfonate (EMS) in jalapeno pepper (Capsicum annuum L. cv. Jalapeno M.) for selecting putative salt-tolerant mutants. Root length was used as an indicator of the LD50 of NaCl in seedlings cultured for 35 days in MS medium containing 0 (without NaCl), 50, 100, 150, 200, or 250 mM NaCl and germination rate as an indicator of the LD50 of EMS in seeds exposed to 0% (without EMS), 0.01%, 0.1%, 0.25%, or 0.5% EMS for 3 and 6 h. We selected salt-tolerant seedlings after 35 days in medium with the determined LD50 of NaCl. Canonical and probit analyses to the LD50 of NaCl and EMS results and multinomial linear regression for germination and survival were applied. LD50 of NaCl (150 mM) and EMS (0.3%) were determined. Seed exposure to 0.5% EMS for 6 h reduced germination (67%) and seedling survival (18%). We obtained four putative salt-tolerant mutants by culturing in medium containing the LD50 of NaCl, two from seeds exposed for 6 h to 0.01 EMS, and one each from of the seeds treated with 0.1% or 0.5% EMS. The results show that it is possible to select putative salt-tolerant mutants of jalapeno pepper through mutagenesis with EMS and in vitro culture in media containing the LD50 of NaCl.