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Xerophytes, naturally growing in desert areas, have evolved multiple protective mechanisms to survive and grow well in harsh environments. Zygophyllum xanthoxylum, a succulent xerophyte with excellent adaptability to adverse arid environments and a fodder shrub with high palatability and nutrient value, colonizes arid areas in China and Mongolia. In this study, we found that Z. xanthoxylum grew better responding to salt condition with a typical feature for halophytes and became more tolerant to drought in the presence of moderate salinity (50 mM NaCl); 50 mM NaCl alleviated deleterious impacts of drought on the growth of Z. xanthoxylum by improving the relative water content, inducing a significant drop in leaf water potential and, concomitantly, increasing leaf turgor pressure and chlorophyll concentrations resulting in an enhancement of overall plant photosynthetic activity. Subsequently, co-expression of genes encoding the tonoplast Na+/H+ antiporter (ZxNHX) and H+-PPase (ZxVP1-1) which involve in leaf Na+ accumulation under stress condition by compartmentalizing Na+ into vacuoles in Z. xanthoxylum significantly improved both drought and salt tolerance in legume forages, Lotus corniculatus L. and Medicago sativa L.

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Mechanisms of Stress Tolerance in Xerophyte Zygophyllum xanthoxylum and Their Application in Genetic Improvement of Legume Forages

Xerophytes, naturally growing in desert areas, have evolved multiple protective mechanisms to survive and grow well in harsh environments. Zygophyllum xanthoxylum, a succulent xerophyte with excellent adaptability to adverse arid environments and a fodder shrub with high palatability and nutrient value, colonizes arid areas in China and Mongolia. In this study, we found that Z. xanthoxylum grew better responding to salt condition with a typical feature for halophytes and became more tolerant to drought in the presence of moderate salinity (50 mM NaCl); 50 mM NaCl alleviated deleterious impacts of drought on the growth of Z. xanthoxylum by improving the relative water content, inducing a significant drop in leaf water potential and, concomitantly, increasing leaf turgor pressure and chlorophyll concentrations resulting in an enhancement of overall plant photosynthetic activity. Subsequently, co-expression of genes encoding the tonoplast Na+/H+ antiporter (ZxNHX) and H+-PPase (ZxVP1-1) which involve in leaf Na+ accumulation under stress condition by compartmentalizing Na+ into vacuoles in Z. xanthoxylum significantly improved both drought and salt tolerance in legume forages, Lotus corniculatus L. and Medicago sativa L.