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
Aluminum （AI） toxicity is a major factor limiting crop production and plant growth in acid soils. The complex inheritance of AI toxicity and tolerance mechanisms in maize has uncharacterized yet. In this study, the ...Aluminum （AI） toxicity is a major factor limiting crop production and plant growth in acid soils. The complex inheritance of AI toxicity and tolerance mechanisms in maize has uncharacterized yet. In this study, the maize inbred line 178 seedlings were treated with 200 μmol L-1 CaCI2＋0 μmol L^-1AICI3 （control） and 200μmol L^-1 CACI2＋60 IJmol L^-1 AICI3 （AI treatment） for I and 6 h, respectively. The experiment was repeated three times. Then a detailed temporal analysis of root gene expression was performed using an Agilent GeneChip with 34 715 genes, only the genes showing more than 2.0-fold difference （P〈0.01） between the control and the AI treatment maize seedlings were analyzed further. Thus, a total of 832 different expression genes, 689 significantly up-regulated and 143 down-regulated, were identified after the seedlings were treated with AI for 6 h. And 60 genes, 59 up-regulated and one down-regulated, were also detected after the seedlings were treated for 1 h. Replicated transcriptome analyses further showed that about 61% of total significantly genes could be annotated based on plant genome resources. Quantitative real-time PCR （qRT-PCT） of some selected candidate genes was used to demonstrate the microarray data, indicating significant differences between the control and AI-treated seedlings. Exposure to AI for 6 h triggered changes in the transcript levels for several genes, which were primarily related to cell wall structure and metabolism, oxidative stress response, membrane transporters, organic acid metabolism, signaling and hormones, and transcription factors, etc. After AI-treated for 1 h, differential abundance of transcripts for several transporters, kinase, and transcription factors were specifically induced. In this study, the diversity of the putative functions of these genes indicates that AI stress for a short stage induced a complex transcriptome changes in maize. These results would further help us to understand rapid and early mechanisms of AI toxicity and tolerance in maize regulated at the transcriptional level.展开更多
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.
基金supported by the National Basic Research Program of China(973 Program,2014CB138705)the National Natural Science Foundation of China(30800687,31071434)the PhD Programs Foundation of Ministry of Education of China(1.20125103110011)
文摘Aluminum （AI） toxicity is a major factor limiting crop production and plant growth in acid soils. The complex inheritance of AI toxicity and tolerance mechanisms in maize has uncharacterized yet. In this study, the maize inbred line 178 seedlings were treated with 200 μmol L-1 CaCI2＋0 μmol L^-1AICI3 （control） and 200μmol L^-1 CACI2＋60 IJmol L^-1 AICI3 （AI treatment） for I and 6 h, respectively. The experiment was repeated three times. Then a detailed temporal analysis of root gene expression was performed using an Agilent GeneChip with 34 715 genes, only the genes showing more than 2.0-fold difference （P〈0.01） between the control and the AI treatment maize seedlings were analyzed further. Thus, a total of 832 different expression genes, 689 significantly up-regulated and 143 down-regulated, were identified after the seedlings were treated with AI for 6 h. And 60 genes, 59 up-regulated and one down-regulated, were also detected after the seedlings were treated for 1 h. Replicated transcriptome analyses further showed that about 61% of total significantly genes could be annotated based on plant genome resources. Quantitative real-time PCR （qRT-PCT） of some selected candidate genes was used to demonstrate the microarray data, indicating significant differences between the control and AI-treated seedlings. Exposure to AI for 6 h triggered changes in the transcript levels for several genes, which were primarily related to cell wall structure and metabolism, oxidative stress response, membrane transporters, organic acid metabolism, signaling and hormones, and transcription factors, etc. After AI-treated for 1 h, differential abundance of transcripts for several transporters, kinase, and transcription factors were specifically induced. In this study, the diversity of the putative functions of these genes indicates that AI stress for a short stage induced a complex transcriptome changes in maize. These results would further help us to understand rapid and early mechanisms of AI toxicity and tolerance in maize regulated at the transcriptional level.
