General and specialized metabolites in peanut roots regulate arbuscular mycorrhizal symbiosis

Arbuscular mycorrhizae(AM)fungi form symbiotic associations with plant roots,providing nutritional benefits and promoting plant growth and defenses against various stresses.Metabolic changes in the roots during AM fungal colonization are key to understanding the development and maintenance of these symbioses.Here,we investigated metabolic changes in the roots of peanut(Arachis hypogaea L.)plants during the colonization and development of AM symbiosis,and compared them to uncolonized roots.The primary changes during the initial stage of AM colonization were in the contents and compositions of phenylpropanoid and flavonoid compounds.These compounds function in signaling pathways that regulate recognition,interactions,and pre-colonization between roots and AM fungi.Flavonoid compounds decreased by 25%when the symbiosis was fully established compared to the initial colonization stage.After AM symbiosis was established,general metabolism strongly shifted toward the formation of lipids,amino acids,carboxylic acids,and carbohydrates.Lipid compounds increased by 8.5%from the pre-symbiotic stage to well-established symbiosis.Lyso-phosphatidylcholines,which are signaling compounds,were only present in AM roots,and decreased in content after the symbiosis was established.In the initial stage of AM establishment,the content of salicylic acid increased two-fold,whereas jasmonic acid and abscisic acid decreased compared to uncolonized roots.The jasmonic acid content decreased in roots after the symbiosis was well established.AM symbiosis was associated with high levels of calcium,magnesium,and D-(+)-mannose,which stimulated seedling growth.Overall,specific metabolites that favor the establishment of AM symbiosis were common in the roots,primarily during early colonization,whereas general metabolism was strongly altered when AM symbiosis was well-established.In conclusion,specialized metabolites function as signaling compounds to establish AM symbiosis.These compounds are no longer produced after the symbiosis between the roots and AM becomes fully established.

Magnesium fertilizer application increases peanut growth and pod yield under reduced nitrogen application in southern China

This study investigated the effect of magnesium application on peanut growth and yield under two nitrogen(N)application rates in acidic soil in southern China.The chlorophyll content,net photosynthetic rate and dry matter accumulation of the N-sensitive cultivar decreased under reduced N treatments,whereas no effect was observed on the relevant indicators in the N-insensitive variety GH1026.Mg application increased the net photosynthetic rate by increasing the expression of genes involved in chlorophyll synthesis and Rubisco activity in the leaves during the pegging stage under 50%N treatment,while no effect on the net photosynthetic rate was observed under the 100%N treatment.The rate of dry matter accumulation at the early growth stage,total dry matter accumulation and pod yield at harvest increased after Mg application under 50%N treatment by increasing the transportation of assimilates from stems and leaves to pods in both peanut varieties,whereas no effect was found under 100%N treatment.Moreover,Mg application increased the NUE under 50%N treatment.No improvement of NUE in either peanut variety was found under 100%N treatment,while Mg application under the 50%N treatment can obtain a higher economic benefit than the 100%N treatment.In acidic soil,application of 307.5 kg ha^(-1)of Mg sulfate fertilizer under 50%reduced nitrogen application is a suitable fertilizer management measure for improving carbon assimilation,NUE and achieve high peanut yields in southern China.

Calcium/calmodulin modulates salt responses by binding a novel interacting protein SAMS1 in peanut(Arachis hypogaea L.)

The Ca^(2+)/CaM signal transduction pathway helps plants adapt to environmental stress. However, our knowledge on the functional proteins of C^(2+)/CaM pathway in peanut(Arachis hypogeae L.) remains limited. In the present study, a novel calmodulin 4(CaM4)-binding protein S-adenosyl-methionine synthetase 1(SAMS1) in peanut was identified using a yeast two-hybrid assay. Expression of AhSAMS1was induced by Ca^(2+), ABA, and salt stress. To elucidate the function of AhSAMS1, physiological and phenotypic analyses were performed with wild-type and transgenic materials. Overexpression of AhSAMS1increased spermidine and spermidine synthesis while decreased the contents of ethylene, thereby eliminating excessive reactive oxygen species(ROS) in transgenic lines under salt stress. AhSAMS1 reduced uptake of Na+and leakage of K+from mesophyll cells, and was less sensitive to salt stress during early seedling growth, in agreement with the induction of SOS and NHX genes Transcriptomics combined with epigenetic regulation uncovered relationships between differentially expressed genes and differentially methylated regions, which raised the salt tolerance and plants growth. Our findings support a model in which the role of AhSAMS1 in the ROS-dependent regulation of ion homeostasis was enhanced by Ca^(2+)/CaM while AhSAMS1-induced methylation was regulated by CaM, thus providing a new strategy for increasing the tolerance of plants to salt stress.

Oil Crops:A Potential Source of Biodiesel

1.Introduction Oil crops such as soybeans,sunflower,canola,rapeseed,and peanuts play a vital role in the agricultural economy,second only to food crops in terms of area and yield.Vegetable oil is known for its high energy density,containing approximately 2.25 times more calories per unit mass than carbohydrates or protein.Therefore,vegetable oil is an important source of energy and provides a variety of fatty acids necessary for human health.

Effects of Allelochemicals on Root Growth and Pod Yield in Response to Continuous Cropping Obstacle of Peanut

Continuous cropping(CC)obstacle is a major threat in legume crops production;however,the underlying mechanisms concerning the roles allelochemicals play in CC obstacle are poorly understood.The current 2-year study was conducted to investigate the effects of different kinds and concentrations of allelochemicals,p-hydroxybenzoic acid(H),cinnamic acid(C),phthalic acid(P),and their mixtures(M)on peanut root growth and productivity in response to CC obstacle.Treatment with H,C,P,and M significantly decreased the plant height,dry weight of the leaves and stems,number of branches,and length of the lateral stem compared with control.Exogenous application of H,C,P,and M inhibited the peanut root growth as indicated by the decreased root morphological characters.The allelochemicals also induced the cell membrane oxidation even though the antioxidant enzymes activities were significantly increased in peanut roots.Meanwhile,treatment with H,C,P,and M reduced the contents of total soluble sugar and total soluble protein.Analysis of ATPase activity,nitrate reductase activity,and root system activity revealed that the inhibition effects of allelochemicals on peanut roots might be due to the decrease in activities of ATPase and NR,and the inhibition of root system.Consequently,allelochemicals significantly decreased the pod yield of peanut compared with control.Our results demonstrate that allelochemicals play a dominant role in CC obstacle-induced peanut growth inhibition and yield reduction through damaging the root antioxidant system,unbalancing the osmolytes accumulation,and decreasing the activities of root-related enzymes.