Phosphorus Limitation Improved Salt Tolerance in Maize Through Tissue Mass Density Increase, Osmolytes Accumulation, and Na+ Uptake Inhibition

Abstract

Low phosphorus (P) availability and salt stress are two major constraints for maize ( Zea mays L.) growth in north China. A combination of salinity and high P rather than low P is more detrimental to the growth of maize. However, little is known about the mechanisms by which P nutrition modifies the salt tolerance and P uptake of maize. The present study aimed to investigate the combined effects of salinity and P on maize growth and P uptake, and to address the physiological mechanisms of salt tolerance influenced by P availability in maize. Seedlings of a local maize cultivar XY335 were grown hydroponically for 35 days under low (5 μM) or sufficient P supply (200 μM) with or without 100 mM NaCl. Root morphological traits, tissue mass density, leaf osmolytes (sugars and proline) accumulation, and Na + /K + ratio were measured to allow evaluation of the combined effects of salinity and P on maize growth and P uptake. Both P deficiency and salinity markedly reduced the growth of maize. However, P deficiency had a more pronounced effect on shoot growth while salinity affected root growth more prominently. Combined effects of P deficiency and salinity on total root length, root surface area, and average root diameter were similar to that of plants grown under salt stress. The combination of P deficiency and salinity treatments had a more pronounced effect on tissue mass density, leaf proline and soluble sugars compared to individual treatment of either low P or NaCl. When exposed to salt stress, maize plants of sufficient P accumulated greater amount of Na + than those under P deficit, but similar amounts of K + were observed between the two P treatments. Salt stress significantly increased shoot P concentration of maize with sufficient P ( P < 0.01), but not for P-deficient plants. In sum, shoots and roots of maize exhibited different responses to P deficiency and salinity, with more marked effect of P deficiency on shoots and of salinity on roots. P deficiency improved salt tolerance of maize plants, which was associated with the increase of tissue mass density, accumulation of osmolytes, reduction of Na + accumulation, and selective absorption of K + over Na + .

Prescience of endogenous regulation in Arabidopsis thaliana by Pseudomonas putida MTCC 5279 under phosphate starved salinity stress condition

“…Present study also shows clustering of roots under P deprived conditions both in presence and absence of RAR, well correlated with higher phosphatase activity. However, under salinity alone and combined stress (P starved-salinity) conditions, lesser number of lateral roots accompanied with lesser root density is contrary to the report of Tang et al 53 . ABA, as a potential chemical signals in auxin independent manner is known to modulate the root system architecture under water stress 54,55 .…”

Genome-Wide Association Study (GWAS) Analysis of Camelina Seedling Germination under Salt Stress Condition

“…One SNP located on chromosome 1 (S1_1910174), control expression of serine/threonine-protein phosphatase PP1 isozyme 9, was identified to be significantly associated with dry weight affected by salt stress (Table 4, Figure 3). Previous studies reported a negative relationship between salinity level and phosphorus metabolism in plant roots and/or shoots [7,45,46]. However, an increase in phosphatase and ATPase activities have been observed in both roots and shoots under salt stress [19,45].…”

“…In general, salinity stress is one of the most harmful abiotic stresses affecting plant growth. Crop production in approximately 20% of the world's arable lands and nearly half of irrigated lands is adversely affected by salinity stress [6,7]. One of the effects of salinity stress is the inhibition of plant photosynthesis and growth by reducing water availability or osmotic stress, ion (Na + and Cl − ) toxicity, nutritional disorders and oxidative stress [7,8].…”

“…Crop production in approximately 20% of the world's arable lands and nearly half of irrigated lands is adversely affected by salinity stress [6,7]. One of the effects of salinity stress is the inhibition of plant photosynthesis and growth by reducing water availability or osmotic stress, ion (Na + and Cl − ) toxicity, nutritional disorders and oxidative stress [7,8]. Previous studies suggested that different plant growth stages might show different levels of salt tolerance [9,10].…”

Comparative metabolomic profiling in the roots of salt-tolerant and salt-intolerant maize cultivars treated with NaCl stress

“…Some amino acids play an adaptive role in mediating osmotic adjustment and protecting subcellular structure (He et al 2015). Proline can remove ROS and alleviate their effects on cell proteins and membranes (Tang et al 2019). Comparing the two maize genotypes revealed higher tendencies for the upregulation of proline in the roots of 'PH6WC', which testifies that NaCl stress can induce salt-tolerant maize to accumulate more proline to reduce membrane damage.…”