The Na+/H+ antiport genes namedTaNHX1andTaNHX2were cloned by screening a salt_stressed wheat cDNA library using rice Na+/H+ antiport cDNA fragment as the probe. Sequencing analysis showed thatTaNHX1was 2 029 bp in le...The Na+/H+ antiport genes namedTaNHX1andTaNHX2were cloned by screening a salt_stressed wheat cDNA library using rice Na+/H+ antiport cDNA fragment as the probe. Sequencing analysis showed thatTaNHX1was 2 029 bp in length and contained a complete ORF of 1 638 bp. TheTaNHX1encodes a polypeptide of 546 amino acids with a transmembrane domain DIFFIYLLPPI.TaNHX2was 1 693 bp in length consisting of a partial ORF followed by a 3′_UTR of 808 bp. The amino acid sequence of these two genes were about 70% identical to the known NHX genes from rice, Arabidopsis and Atriplex. A RT_PCR assay showed that the level ofTaNHX1transcripts was increased and reached a steady higher level in the seedlings after 3 h treatment with 400 mmol/L NaCl.展开更多
Maize is one of the most important crops worldwide, but it suffers from salt stress when grown in saline-alkaline soil. There is therefore an urgent need to improve maize salt tolerance and crop yield. In this study, ...Maize is one of the most important crops worldwide, but it suffers from salt stress when grown in saline-alkaline soil. There is therefore an urgent need to improve maize salt tolerance and crop yield. In this study, the SsNHX1 gene of Suaeda salsa, which encodes a vacuolar membrane Na~+/H~+ antiporter, was transformed into the maize inbred line 18-599 by Agrobacterium-mediated transformation. Transgenic maize plants overexpressing the SsNHX1 gene showed less growth retardation when treated with an increasing NaCl gradient of up to 1%, indicating enhanced salt tolerance. The improved salt tolerance of transgenic plants was also demonstrated by a significantly elevated seed germination rate(79%) and a reduction in seminal root length inhibition. Moreover, transgenic plants under salt stress exhibited less physiological damage. SsNHX1-overexpressing transgenic maize accumulated more Na~+ and K~+ than wild-type(WT) plants particularly in the leaves, resulting in a higher ratio of K~+/Na~+ in the leaves under salt stress. This result revealed that the improved salt tolerance of SsNHX1-overexpressing transgenic maize plants was likely attributed to SsNHX1-mediated localization of Na~+ to vacuoles and subsequent maintenance of the cytosolic ionic balance. In addition, SsNHX1 overexpression also improved the drought tolerance of the transgenic maize plants, as rehydrated transgenic plants were restored to normal growth while WT plants did not grow normally after dehydration treatment. Therefore, based on our engineering approach, SsNHX1 represents a promising candidate gene for improving the salt and drought tolerance of maize and other crops.展开更多
文摘The Na+/H+ antiport genes namedTaNHX1andTaNHX2were cloned by screening a salt_stressed wheat cDNA library using rice Na+/H+ antiport cDNA fragment as the probe. Sequencing analysis showed thatTaNHX1was 2 029 bp in length and contained a complete ORF of 1 638 bp. TheTaNHX1encodes a polypeptide of 546 amino acids with a transmembrane domain DIFFIYLLPPI.TaNHX2was 1 693 bp in length consisting of a partial ORF followed by a 3′_UTR of 808 bp. The amino acid sequence of these two genes were about 70% identical to the known NHX genes from rice, Arabidopsis and Atriplex. A RT_PCR assay showed that the level ofTaNHX1transcripts was increased and reached a steady higher level in the seedlings after 3 h treatment with 400 mmol/L NaCl.
基金supported by the National Natural Science Foundation of China(31561143014,30800687,31071434,and 31522041)the Major Project of Education Department of Sichuan Province,China(15ZA0022)
文摘Maize is one of the most important crops worldwide, but it suffers from salt stress when grown in saline-alkaline soil. There is therefore an urgent need to improve maize salt tolerance and crop yield. In this study, the SsNHX1 gene of Suaeda salsa, which encodes a vacuolar membrane Na~+/H~+ antiporter, was transformed into the maize inbred line 18-599 by Agrobacterium-mediated transformation. Transgenic maize plants overexpressing the SsNHX1 gene showed less growth retardation when treated with an increasing NaCl gradient of up to 1%, indicating enhanced salt tolerance. The improved salt tolerance of transgenic plants was also demonstrated by a significantly elevated seed germination rate(79%) and a reduction in seminal root length inhibition. Moreover, transgenic plants under salt stress exhibited less physiological damage. SsNHX1-overexpressing transgenic maize accumulated more Na~+ and K~+ than wild-type(WT) plants particularly in the leaves, resulting in a higher ratio of K~+/Na~+ in the leaves under salt stress. This result revealed that the improved salt tolerance of SsNHX1-overexpressing transgenic maize plants was likely attributed to SsNHX1-mediated localization of Na~+ to vacuoles and subsequent maintenance of the cytosolic ionic balance. In addition, SsNHX1 overexpression also improved the drought tolerance of the transgenic maize plants, as rehydrated transgenic plants were restored to normal growth while WT plants did not grow normally after dehydration treatment. Therefore, based on our engineering approach, SsNHX1 represents a promising candidate gene for improving the salt and drought tolerance of maize and other crops.
