BackgroundChanges in rainfall induced by climate change will likely influence the utilization of water resources and affect the nutrient cycle in plants in the water-limited desert steppe. In order to understand the response of nitrogen and phosphorus resorption characteristics of plant leaves to precipitation changes, this study compared the nitrogen (N) resorption efficiency, phosphorus (P) resorption efficiency and influencing factors of plants in a desert steppe through water treatment experiments.MethodsA 4-year field experiment was performed to examine the response and influencing factors of nitrogen (N) and phosphorus resorption efficiency of five dominant plants in Stipa breviflora desert steppe to simulated precipitation change in Inner Mongolia, with four simulated precipitation gradients including reducing water by 50%, natural precipitation, increasing water by 50%, increasing water by 100%.ResultsCompared with natural precipitation, increasing water by 100% significantly increased soil moisture, and significantly increased the aboveground biomass of S. breviflora, C. songorica, A. frigida, decreased the N concentrations in green leaves of S. breviflora, Cleistogenes songorica, Artemisia frigida, Kochia prostrata, decreased the N concentrations in senesced leaves of C. songorica, decreased the P concentrations in green leaves of K. prostrata and Convolvulus ammannii, decreased the NRE of S. breviflora. NRE was significantly negatively correlated with N concentration in senesced leaves, and PRE was significantly negatively correlated with P concentration in senesced leaves.ConclusionsIncreasing water indirectly reduces NRE by reducing plant leaf green leaves nitrogen concentration, and decreasing water indirectly reduces PRE by reducing soil moisture.

Oil is one of the main components in maize kernels. Increasing the total oil content (TOC) is favorable to optimize feeding requirement by improving maize quality. To better understand the genetic basis of TOC, quantitative trait loci (QTL) in four double haploid (DH) populations were explored. TOC exhibited continuously and approximately normal distribution in the four populations. The moderate to high broad-sense heritability (67.00-86.60%) indicated that the majority of TOC variations are controlled by genetic factors. A total of 16 QTLs were identified across all chromosomes in a range of 3.49-30.84% in term of phenotypic variation explained. Among them, six QTLs were identified as the major QTLs that explained phenotypic variation larger than 10%. Especially, qOC-1-3 and qOC-2-3 on chromosome 9 were recognized as the largest effect QTLs with 30.84% and 21.74% of phenotypic variance, respectively. Seventeen well-known genes involved in fatty acid metabolic pathway located within QTL intervals. These QTLs will enhance our understanding of the genetic basis of TOC in maize and offer prospective routes to clone candidate genes regulating TOC for breeding program to cultivate maize varieties with the better grain quality.

Longan (Dimocarpus Longan) is one of the most important fruit crops in Southern China. Lack of available Mg in acidic soil conditions is a limitation to further increasing longan yield. Magnesium transporter (MGT/MRS2) mediates the uptake, transport, and redistribution of Mg2+ in higher plants. To understand the role of MGTs family members in longan Mg deficiency. We identified and analyzed the protein characteristics, phylogeny, expression changes, subcellular localization, and transcriptional regulation of DlMGTs members. The results showed that, twelve DlMGTs are localized in the cell membrane, chloroplast, and nucleus. The evolutionary differences in MGTs between herbaceous and woody species in different plants. The DlMGTs promoters contained many cis-acting elements and transcription factor binding sites related to the hormone, environmental, and stress response. Subcellular localization assays showed that DlMGT1 localizes in the cell membrane of Arabidopsis protoplasts. The candidate transcription factor DlGATA16, which may regulate the expression of DlMGT1, was localized in the nucleus of tobacco leaves. Dual luciferase analysis demonstrated that DlGATA16 is a potential factor regulating the transcriptional activity of DlMGT1. In this study, we identified and analyzed DlMGTs on a genome-wide scale and the subcellular localization and interaction of DlMGT1 and DlGATA16, which has important implications for further functional analysis studies of MGTs and the use of MGT for longan genetic improvement.

IntroductionSalinity critically affects the growth and development of alfalfa (Medicago sativa), making it necessary to understand the molecular mechanism of alfalfa’s adaptation to salt stress.MethodsIn this study, alfalfa roots were subjected to salt stress and transcriptomics and metabolomics analyses were performed.ResultsThe results showed that flavonoid synthesis, hormone synthesis, and transduction pathways may be involved in the alfalfa salt stress adaptation reaction, and that they are related. Combined analysis of differential genes and differential metabolites found that dihydroquercetin and beta-ring hydroxylase (LUT5), ABA responsive element binding factor 2 (ABF2), protein phosphatase PP2C (PP2C) and abscisic acid (ABA) receptor PYL2 (PYL), luteolinidin was significantly correlated with PP2C and phytochrome-interacting factor 4 (PIF4) and (+)-7-isomethyl jasmonate were significantly correlated with flavonol synthase (FLS) gene. (+)-7-isomethyl jasmonate and homoeriodictyol chalcone were significantly correlated with peroxidase (POD). POD was significantly up-regulated under NaCl stress for 6 and 24 h. Moreover, flavonoids, gibberellin (GA), jasmonic acid (JA) and ABA were suggested to play an important role in alfalfa’s response to salt stress. Further, GA,ABA, and JA may be involved in the regulation of flavonoids to improve alfalfa’s salt tolerance, and JA may be a key signal to promote the synthesis of flavonoids. DiscussionThis study revealed the possible molecular mechanism of alfalfa adaptation to salt stress, and identified a number of salt-tolerance candidate genes from the synthesis and signal transduction pathways of flavonoids and plant hormones, providing new insights into the regulatory network of alfalfa response to salt stress.

Although foxtail millet, as small Panicoid crop, is of drought resilient, drought stress has a significant effect on panicle of foxtail millet at the yield formation stage. In this study, the changes of panicle morphology, photosynthesis, antioxidant protective enzyme system, reactive oxygen species (ROS) system, and osmotic regulatory substance and RNA-seq of functional leaves under light drought stress (LD), heavy drought stress (HD), light drought control (LDCK) and heavy drought control (HDCK) were studied to get a snap-shot of specific panicle morphological changes, physiological responses and related molecular mechanisms. The results showed that the length and weight of panicle had decreased, but with increased empty abortive rate, and then yield dropped off 14.9% and 36.9%, respectively. The photosynthesis of millet was significantly decreased, like net photosynthesis rate, stomatal conductance and transpiration rate, especially under HD treatment with reluctant recovery from rehydration. Under LD and HD treatment, the peroxidase (POD) was increased by 34% and 14% and the same as H2O2 by 34.7% and 17.2% compared with LDCK and HDCK. The ability to produce and inhibit O2- free radicals under LD treatment was higher than HD. The content of soluble sugar was higher under LD treatment but the proline was higher under HD treatment. Through RNA-seq analysis, there were 2,393 and 3,078 different genes expressed under LD and HD treatment. According to the correlation analysis between weighted gene coexpression network analysis (WGCNA) and physiological traits, the co-expression network of several modules with high correlation was constructed, and some hub genes of millet in response to drought stress were found. The expression changes relating to carbon fixation, sucrose and starch synthesis, lignin synthesis, gibberellin synthesis, and proline synthesis of millet were specifically analyzed. These findings provide a full perspective on how drought affects the yield formation of foxtail millet by constructing one work model thereby providing theoretical foundation for hub genes exploration and drought resistance breeding of foxtail millet.

Metabolomics is an indispensable part of modern systems biotechnology, applied in the diseases’ diagnosis, pharmacological mechanism, and quality monitoring of crops, vegetables, fruits, etc. Metabolomics of fruit trees has developed rapidly in recent years, and many important research results have been achieved in combination with transcriptomics, genomics, proteomics, quantitative trait locus (QTL), and genome-wide association study (GWAS). These research results mainly focus on the mechanism of fruit quality formation, metabolite markers of special quality or physiological period, the mechanism of fruit tree’s response to biotic/abiotic stress and environment, and the genetics mechanism of fruit trait. According to different experimental purposes, different metabolomic strategies could be selected, such as targeted metabolomics, non-targeted metabolomics, pseudo-targeted metabolomics, and widely targeted metabolomics. This article presents metabolomics strategies, key techniques in metabolomics, main applications in fruit trees, and prospects for the future. With the improvement of instruments, analysis platforms, and metabolite databases and decrease in the cost of the experiment, metabolomics will prompt the fruit tree research to achieve more breakthrough results.