ABSTRACT
C2H2 zinc finger proteins (ZFPs) play important roles in plant development and response to abiotic stresses, and have been studied extensively. However, there are few studies on ZFPs in mangroves and mangrove associates, which represent a unique plant community with robust stress tolerance. MpZFP1, which is highly induced by salt stress in the mangrove associate Millettia pinnata, was cloned and functionally characterized in this study. MpZFP1 protein contains two zinc finger domains with conserved QALGGH motifs and targets to the nucleus. The heterologous expression of MpZFP1 in Arabidopsis increased the seeds' germination rate, seedling survival rate, and biomass accumulation under salt stress. The transgenic plants also increased the expression of stress-responsive genes, including RD22 and RD29A, and reduced the accumulation of reactive oxygen species (ROS). These results indicate that MpZFP1 is a positive regulator of plant responses to salt stress due to its activation of gene expression and efficient scavenging of ROS.
Subject(s)
Arabidopsis/physiology , CYS2-HIS2 Zinc Fingers , Gene Expression Regulation, Plant , Millettia/physiology , Plant Proteins/metabolism , Plants, Genetically Modified/physiology , Salt Tolerance , Arabidopsis/genetics , Arabidopsis/metabolism , Droughts , Millettia/genetics , Millettia/metabolism , Plant Proteins/genetics , Plants, Genetically Modified/genetics , Plants, Genetically Modified/metabolism , Stress, PhysiologicalABSTRACT
Nickel is widely spread by different anthropogenic activities and shows toxicity for plant growth and development. Whether rhizobia symbiotically fix nitrogen can eliminate or reduce nickel toxic effect on plant or not is still unknown. This study was aimed to investigate the effect of different rhizobia genus inoculation on growth, nitrogen fixing ability, metal accumulation and enzymatic antioxidative balance of Pongamia pinnnaa. Inoculation with Rhizobium pisi and Ochrobacterium pseudogrignonense increased the all the growth parameters both in 0 and 40â¯mg/kg nickel as comparison with control. Only shoot length increased in presence of nitrogen as compared with no supply of nitrogen. Nitrogen content also increased both in rhizobia inoculation as compared to no nitrogen supply and non-inoculation control, respectively. Nickel uptake was higher in shoots and leaves but lower in roots in case of inoculation as compared to non-inoculation control. Rhizobia inoculation improved the plant antioxidant capacity by increasing the activity of enzymatic scavengers catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) and ascorbate (GR). However, 40â¯mg/kg of nickel adding showed mostly effect on the activity CAT, SOD, POD in leaves. All the enzymatic activity showed a significant increase in absence of nitrogen supply as compared nitrogen supply. Our results suggested that rhizobia inoculation effectively mediated nickel stress for legume plants by increasing nitrogen supplement and inducing antioxidant capacity.
Subject(s)
Brucellaceae/physiology , Millettia/physiology , Nickel/metabolism , Rhizobium/physiology , Antioxidants , Ascorbic Acid , Catalase/metabolism , Millettia/metabolism , Nitrogen , Oxidation-Reduction , Plant Roots/metabolism , Superoxide Dismutase/metabolism , SymbiosisABSTRACT
Soil salinity is gradually becoming a threat to the global economy by affecting agricultural productivity worldwide. Here, we analyze the salinity tolerance of Pongamia pinnata with an insight into the underlying physiological and molecular responses. Despite a reduction in net photosynthetic rate, P. pinnata efficiently maintained its leaf water potentials even at 500mM NaCl for 15days and displayed no visible stress symptoms. Na+ localization analysis using CoroNa-Green AM revealed effective Na+ sequestration in the roots when compared to leaves. Elemental analysis demonstrated that roots accumulated more of Na+ while K+ content was higher in leaves. At the molecular level, salt stress significantly induced the expression levels of salt overly sensitive1 (SOS1), SOS2, SOS3, high affinity K+ transporter (HKT1), ABA biosynthetic and receptor genes (NCED and PYL4), guaiacol peroxidase (POD) exclusively in roots while tonoplast localized Na+/H+ exchanger (NHX1) was significantly enhanced in leaves. Our results clearly demonstrate that leaves and roots of Pongamia exhibit differential responses under salt stress although roots are more efficient in sequestering the Na+ ions. The present study provides crucial inputs for understanding salt tolerance in a tree species which can be further utilized for developing salt tolerance in higher plants.
Subject(s)
Millettia/physiology , Salt-Tolerant Plants/physiology , Trees/physiology , Biofuels , Chlorophyll/metabolism , Microscopy, Confocal , Microscopy, Electron, Scanning , Millettia/metabolism , Millettia/ultrastructure , Photosynthesis/physiology , Photosystem II Protein Complex/physiology , Plant Leaves/physiology , Plant Leaves/ultrastructure , Plant Transpiration/physiology , Polymerase Chain Reaction , Spectrometry, X-Ray Emission , Trees/metabolism , Trees/ultrastructureABSTRACT
Macroinvertebrate colonization and breakdown of Pongamia pinnata and Morinda tinctoria leaves were studied in an astatic pond in Madura College, Madurai. Morinda tinctoria leaves broke down fasterthan the leaves of P. pinnata. Breakdown capacities of astatic pond cannot be attributed to colonization of macroinvertebrates. Instead, microbial processing, and abiotic fragmentation are suggested as factors controlling breakdown rates. Tanypus sp (midgelarva) was abundant in leaf bags during the experimental period. This midge-larva appeared to use litter accumulations as a microhabitat that provided shelter and a rich supply of food in the form of organic matter Their abundance and regular occurrence of two leaves suggest that midge larvae enhance leaf fragmentation and possibly mediate the incorporation of organic matter in pond sediments once the plant tissue is sufficiently macerated.
