Screen Of TvNHX1-transformed Maize Linesand Analysis Of The Responses To NaCl And NaHCO₃Stresses

Zea mays is one of the largest cereal crops worldwide, and occupies a veryimportant position in agricultural production. Saline-alkali stresses are the most seriousfactors limiting the productivity of maize in recent years. To improve the tolerance ofmaize to saline-alkali stresses is significantly important for crop production.In this study, we screened the Tvnhx1-transformed maize, and analyzed theexpression of TvNHX1and ZmNHX1, and physiological characteristics in Tvnhx1-transgenic maize lines under NaCl and NaHCO3stresses. The main contents and resultsare as follow.Tvnhx1-transformed maize lines were09-1、09-2、09-5and09-11. Thirty-fiveTvnhx1-transgenic T1plants were selected after200mmol/L NaCl treatment andamplified Tvnhx1gene by PCR. Twenty Tvnhx1-transgenic T2plants were harvestedafter screening by spraying PPT and PCR.Expression of TvNHX1and ZmNHX1gene in Tvnhx1-transgenic maize after200mmol/L NaCl and NaHCO3treatment was studied by semi-quantitative RT-PCR.The results showed that TvNHX1gene were up-regulated in most of transgenic maizelines under salt and alkali stress. The up-regulated expression of TvNHX1genes couldhave an impact on ZmNHX1expression, thus improving stress resistance of transgenicmaize plants.SOD activity, MDA content in leaves, and Na+、K+、Ca2+、Mg2+contents of rootsand leaves of TvNHX1-transgenic and non-transgenic maize under200mmol/LNaCl andNaHCO3treatment were measured. The result showed that SOD activity in09-5transgenic maize line was higher than in non-transgenic control. Na+concentration inroots and leaves of four transgenic maize lines were lower than in non-transgeniccontrol, and Mg2+concentration were higher than those of non-transgenic maize undersalt stress or alkaline stress. K+and Ca2+concentration were different in various lines. Itwas possible that overexpreesion of TvNHX1affected SOD activity and MDA content,and reduced Na+excessive cumulative in maize under salt-alkaline stresses andimproved salt-alkaline tolerance in TvNHX1-transgenic maize.