PHOSPHORUS-STARVATION TOLERANCE 1 (OsPSTOL1) is prevalent in upland rice and enhances root growth and hastens low phosphate signaling in wheat.

PHOSPHORUS-STARVATION TOLERANCE 1 (OsPSTOL1) is a variably present gene that benefits crown root growth and phosphorus (P) sufficiency in rice (Oryza sativa). To explore the ecophysiological importance of this gene, we performed a biogeographic survey of landraces and cultivars, confirming that functional OsPSTOL1 alleles prevail in low nutrient and drought-prone rainfed ecosystems, whereas loss-of-function and absence haplotypes predominate in control-irrigated paddy varieties of east Asia. An evolutionary history analysis of OsPSTOL1 and related genes in cereal, determined it and other genes are kinase-only domain derivatives of membrane-associated receptor like kinases. Finally, to evaluate the potential value of this kinase of unknown function in another Gramineae, wheat (Triticum aestivum) lines overexpressing OsPSTOL1 were evaluated under field and controlled low P conditions. OsPSTOL1 enhances growth, crown root number, and overall root plasticity under low P in wheat. Survey of root and shoot crown transcriptomes at two developmental stages identifies transcription factors that are differentially regulated in OsPSTOL1 wheat that are similarly controlled by the gene in rice. In wheat, OsPSTOL1 alters the timing and amplitude of regulators of root development in dry soils and hastens induction of the core P-starvation response. OsPSTOL1 and related genes may aid more sustainable cultivation of cereal crops.

Identification of Rf Genes in Hexaploid Wheat (Triticumaestivum L.) by RNA-Seq and Paralog Analyses.

Among the natural mechanisms used for wheat hybrid breeding, the most desirable is the system combining the cytoplasmic male sterility (cms) of the female parent with the fertility-restoring genes (Rf) of the male parent. The objective of this study was to identify Rf candidate genes in the wheat genome on the basis of transcriptome sequencing (RNA-seq) and paralog analysis data. Total RNA was isolated from the anthers of two fertility-restorer (Primépi and Patras) and two non-restorer (Astoria and Grana) varieties at the tetrad and late uninucleate microspore stages. Of 36,912 differentially expressed genes (DEGs), 21 encoding domains in known fertility-restoring proteins were selected. To enrich the pool of Rf candidates, 52 paralogs (PAGs) of the 21 selected DEGs were included in the analyses. The expression profiles of most of the DEGs and PAGs determined bioinformatically were as expected (i.e., they were overexpressed in at least one fertility-restorer variety). However, these results were only partially consistent with the quantitative real-time PCR data. The DEG and PAG promoters included cis-regulatory elements common among PPR-encoding genes. On the basis of the obtained results, we designated seven genes as Rf candidate genes, six of which were identified for the first time in this study.

Response of spring wheat and potato to foliar application of Zn, Mn and EDTA fertilizers on 137Cs uptake.

The impact of foliar fertilization with zinc (ZnSO4) and manganese (MnSO4 on 137Cs uptake by spring wheat and potato was studied. The experiments were conducted during 3 years (2014-2016) in a137Cs-contaminated area, Zhytomyr region of Ukraine. The fertilization was carried out on podzolic loamy sand soil, poor in most of the microelements. Both crops were fertilized at four successive stages of growth. Foliar application of fertilizers caused higher yield of wheat grain/straw and potato tubers yield in 2014-2015 years but had no effect in 2016. Thus, the overall effect of fertilization between 2014 and 2016 was less pronounced and generally insignificant. Application of Zn, Mn and EDTA reduced 137Cs uptake by wheat grain and potato tubers, when fertilized at earlier stages of growth and development in years 2014 and 2015 by factor 1.5-2.0, while in 2016 the effect was generally statistically insignificant. It is suggested, that reduction of 137Cs uptake by spring wheat and potato, at least partly, was caused by an effect of radionuclide dilution due to the higher biomass of the plants. A foliar spray of EDTA at earlier stages of plant growth and development may be considered as a potential countermeasure aiming reducing 137Cs uptake from soil to plants, even if such effect appeared to be conditional.

Sequenced application of glutathione as an antioxidant with an organic biostimulant improves physiological and metabolic adaptation to salinity in wheat.

Globally, salinity threatens the agricultural crops productivity by inhibiting plant growth and development through osmotic stress and ionic cytotoxicity. The polygenic nature of salinity offers several pragmatic shotgun approaches to improve salinity tolerance. The present study investigated the potential of glutathione (GSH; 1 mM) as an antioxidant and moringa leaf extract (MLE; 3%) as an organic biostimulant applied in sequence as seed priming and foliar spray on wheat growth, physiology and metabolic adaptation under saline conditions (9.16 dS m-1). Plants without any treatment and water spray (H2O) were considered controls. Salinity induced osmotic stress reduced the plant tissue water status and photosynthetic performance, and perturbed ionic (K+/Na+, Ca2+/Na+, K++Ca2+/Na+) and hormonal (IAA, GA3, zeatin, ABA) homeostasis, consequently affected growth and yield in wheat. Sequenced applied MLE and/or GSH improved osmotic stress tolerance by stabilizing membrane integrity and decreasing electrolyte leakage. These positive results were owed to enhanced endogenous GSH and ascorbate levels. Improved tissue water status was attributed to increased osmotic adjustment, better ionic and hormonal homeostasis contributed to improving photosynthetic efficiency and growth under salinity. Exogenously applied MLE and GSH sequences improved grain yield, which was attributed to the maintenance of green leaf area and delayed senescence associated with an increase in photosynthetic pigments and chlorophyll fluorescence traits. In crux, exogenous applied MLE and/or GSH can be the best physiological strategy to reduce the deleterious effects of salinity and improve physiological and metabolic adaptation in wheat under saline field conditions.

Light promoted brown staining of protoplasm by Ag+ is ideal to test wheat pollen viability rapidly.

Pollen viability is crucial for wheat breeding programs. The unique potential of the protoplasm of live cells to turn brown due to the synthesis of silver nanoparticles (AgNPs) through rapid photoreduction of Ag+, was exploited for testing wheat pollen viability. Ag+-viability test medium (consisting of 0.5 mM AgNO3 and 300 mM KNO3) incubated with wheat pollen turned brown within 2 min under intense light (~600 µmol photon flux density m-2s-1), but not in dark. The brown medium displayed AgNPs-specific surface plasmon resonance band in its absorption spectrum. Light microscopic studies showed the presence of uniformly stained brown protoplasm in viable pollen incubated with Ag+-viability medium in the presence of light. Investigations with transmission electron microscope coupled with energy dispersive X-ray established the presence of distinct 5-35 nm NPs composed of Ag. Powder X-ray diffraction analysis revealed that AgNPs were crystalline and biphasic composed of Ag0 and Ag2O. Conversely, non-viable pollen and heat-killed pollen did not turn brown on incubation with Ag+-medium in light. We believe that the viable wheat pollen turn brown rapidly by bio-transforming Ag+ to AgNPs through photoreduction. Our findings furnish a novel simplest and rapid method for testing wheat pollen viability.

Comprehensive analysis of polygalacturonase gene family highlights candidate genes related to pollen development and male fertility in wheat (Triticum aestivum L.).

MAIN CONCLUSION: Four polygalacturonase gene family members were highlighted that contribute to elucidate the roles of polygalacturonase during the fertility conversion process in male-sterile wheat. Polygalacturonase (PG) belongs to a large family of hydrolases with important functions in cell separation during plant growth and development via the degradation of pectin. Specific expressed PGs in anthers may be significant for male sterility research and hybrid wheat breeding, but they have not been characterized in wheat (Triticum aestivum L.). In this study, we systematically studied the PG gene family using the latest published wheat reference genomic information. In total, 113 wheat PG genes were identified, which could be classified into six categories A-F according to their structure characteristics and phylogenetic comparisons with Arabidopsis and rice. Polyploidy and segmental duplications in wheat were proved to be mainly responsible for the expansion of the wheat PG gene family. RNA-seq showed that TaPGs have specific temporal and spatial expression characteristics, in which 12 TaPGs with spike-specific expression patterns were detected by qRT-PCR in different fertility anthers of KTM3315A, a thermo-sensitive cytoplasmic male-sterile wheat. Four of them specific upregulated (TaPG09, TaPG95, and TaPG93) or downregulated (TaPG87) at trinucleate stage of fertile anthers, and further aligning with the homologous in Arabidopsis revealed that they may undertake functions such as anther dehiscence, separation of pollen, pollen development, and pollen tube elongation, thereby inducing male fertility conversion in KTM3315A. These findings facilitate function investigations of the wheat PG gene family and provide new insights into the fertility conversion mechanism in male-sterile wheat.

Phenotypic and genetic variation in phosphorus-deficiency-tolerance traits in Chinese wheat landraces.

BACKGROUND: Phosphorus deficiency is a major limiting factors for affecting crop production globally. To understand the genetic variation of phosphorus-deficiency-tolerance, a total of 15 seedling traits were evaluated among 707 Chinese wheat landraces under application of phosphorus (AP) and non-application of phosphorus (NP). A total of 18,594 single-nucleotide polymorphisms and 38,678 diversity arrays technology sequencing markers were used to detect marker-trait associations under AP and NP. RESULTS: Top ten genotypes with extremely tolerance and bottommost ten genotypes with extremely sensitivity were selected from 707 Chinese wheat landraces for future breeding and genetic analysis. A total of 55 significant markers (81 marker-trait associations) for 13 traits by both CMLM and SUPER method. These were distributed on chromosomes 1A, 1B, 2A, 2B, 2D, 3A, 4B, 5A, 5B, 6A, 6B, 6D, 7A and 7B. Considering the linkage disequilibrium decay distance, 25 and 12 quantitative trait loci (QTL) were detected under AP and NP, respectively (9 QTL were specific to NP). CONCLUSIONS: The extremely tolerant landraces could be used for breeding phosphorus-deficiency-tolerant cultivars. The QTL could be useful in wheat breeding through marker-assisted selection. Our findings provide new insight into the genetic analysis of P-deficiency-tolerance, and will be helpful for breeding P-deficiency-tolerant cultivars.

The effect of supplementation of the soil-like substrate with wheat straw mineralized to different degrees on wheat productivity in closed ecosystems.

Successful incorporation of soil-like substrate (SLS) into biotechnical life support systems is often complicated by the necessity to maintain the balance between flows of mineral elements taken up from the substrate by growing plants and mineral elements added to the SLS as components of mineralized plant inedible biomass. An imbalance between these two flows can be caused by the addition of recalcitrant plant waste such as wheat straw. The purpose of this study was to determine whether the availability of essential nutrients to be taken up by the roots of the wheat plants grown on the SLS could be enhanced by supplementing the SLS with the products derived from wheat straw subjected to different levels of physicochemical mineralization in the aqueous solution of hydrogen peroxide. Different degrees of straw mineralization were achieved by using different ratios of the aqueous solution of hydrogen peroxide to straw. The study showed that supplementation of the SLS with insufficiently oxidized products of physicochemical mineralization of straw resulted in a decrease in the grain yields. The inhibitory effect of the straw subjected to physicochemical oxidation increased with a decrease in the degree to which the straw had been oxidized. Only supplementation with the straw mineralized to the highest possible degree did not inhibit plant growth and development, and the crop yield in that treatment was higher than in the other treatments.

Nitrogen supply modulates nitrogen remobilization and nitrogen use of wheat under supplemental irrigation in the North China Plain.

Excessive nitrogen (N) input and irrigation exacerbate N leaching in winter wheat production in the North China Plain (NCP). To explore the optimal N for better N remobilization and higher N utilization of wheat under water-saving irrigation will be conductive to less environmental contamination. A field experiment was conducted at 300 (N300), 240 (N240), 180 (N180), and 0 (N0) kg N ha-1 of N application under supplemental irrigation (SI) that brought the relative soil water content (RSWC) to 70% at jointing and 65% at anthesis. Compared with N0, N180 improved the free amino acid content in the flag leaf and grain after anthesis, dry matter and plant N accumulation at maturity, N translocation amount of vegetable organs and its contribution to grain from anthesis to maturity. Compared to N240 and N300, N180 increased the N translocation efficiency of vegetable organs, and reduced the soil NO3-N residue in the 60-180 cm soil layer, which contributing to no significant reduction in grain yield and grain protein yield, but higher grain N recovery efficiency (GREN), N recovery efficiency (REN), and N partial factor productivity (PFPN). Positive relationships were found between leaf N translocation efficiency and grain yield, grain protein yield, PFPN, GREN, and REN. Therefore, N180 is appropriate to obtain a steady grain yield over 7.5 t ha-1 for at least 2 years under SI based on RSWC in the NCP.

Integrative application of licorice root extract or lipoic acid with fulvic acid improves wheat production and defenses under salt stress conditions.

Although different plant extracts and plant growth regulators are used as biostimulants to support plants grown under salt stress conditions, little information is available regarding the use of licorice root extract (LRE) or lipoic acid (LA) as biostimulants. Studies on the application of LRE or LA in combination with fulvic acid (FA) as natural biostimulants have not been performed. Therefore, in this study, two pot experiments were conducted to evaluate the potential effects of LRE (5 g L-1) or LA (0.1 mM) supplemented as a foliar spray in combination with FA (0.2 mg kg-1 soil) on osmoprotectants and antioxidants, growth characteristics, photosynthetic pigments, nutrient uptake, and yield as well as on the anatomical features of the stems and leaves of wheat plants irrigated with three levels of saline water (0.70, 7.8, and 14.6 dSm-1). Moderate (7.8 dSm-1) and high (14.6 dSm-1) levels of salinity caused a significant (p ≤ 0.05) increase in the activities of SOD, APX CAT, POX, and GR as well as in electrolyte leakage, malondialdehyde level, and reactive oxygen species (O2‒ and H2O2) levels compared to those in controls (plants irrigated with tap water). However, the leaf relative water content, membrane stability index, NPK uptake, leaf area, plant height, spike length, straw yield, grain yield, and protein content of wheat grains significantly (p ≤ 0.05) decreased. Addition of LRE or LA and/or HA to wheat plants under saline stress significantly (p ≤ 0.05) enhanced their morphological and physio-biochemical characteristics in parallel with increases in the activities of enzymatic antioxidants. Salinity stress altered (p ≤ 0.05) wheat stem and leaf structures; however, treatment with LRE + FA significantly improved these negative effects. These findings indicate that FA + LRE treatment significantly improved the antioxidant defense system of the plants, thereby reducing ROS levels and increasing wheat growth and production under saline conditions.

In Vivo Modulation of Arbuscular Mycorrhizal Symbiosis and Soil Quality by Fungal P Solubilizers.

Phosphorus (P) is an essential nutrient with low bioavailability in soils for plant growth. The use of P solubilization fungi (PSF) has arisen as an eco-friendly strategy to increase this nutrient's bioavailability. The effect of PSF inoculation and its combination with P-transporting organisms (arbuscular mycorrhizal fungi, AMF) on plant growth has been previously studied. However, these studies did not evaluate the combined effect of PSF and AMF inoculation on plant growth, symbiosis, and soil quality. Therefore, the aim of this study is to assess the impact of PSF on the AMF-wheat symbiosis establishment and efficiency, considering the effect on plant growth and soil quality. We performed a greenhouse experiment with wheat under different treatments (+/-AMF: Rhizophagus irregularis; +/-PSF strains: Talaromyces flavus, T. helicus L7B, T. helicus N24, and T. diversus) and measured plant growth, AMF root colonization, symbiotic efficiency, and soil quality indicators. No interaction between PSF and R. irregularis was found in wheat growth, showcasing that their combination is not better than single inoculation. T. helicus strains did not interfere with the AMF-wheat symbiosis establishment, while T. diversus and T. flavus decreased it. The symbiotic efficiency was increased by T. flavus and T. helicus N24, and unchanged with T. helicus L7B and T. diversus inoculation. The soil quality indicators were higher with microbial co-inoculation, particularly the alkaline phosphatases parameter, showing the beneficial role of fungi in soil. This work highlights the importance of microbial interactions in the rhizosphere for crop sustainability and soil quality improvement, assessing the effects of PSF on AMF-wheat symbiosis.

Variation in phosphorus and sulfur content shapes the genetic architecture and phenotypic associations within the wheat grain ionome.

Dissection of the genetic basis of wheat ionome is crucial for understanding the physiological and biochemical processes underlying mineral accumulation in seeds, as well as for efficient crop breeding. Most of the elements essential for plants are metals stored in seeds as chelate complexes with phytic acid or sulfur-containing compounds. We assume that the involvement of phosphorus and sulfur in metal chelation is the reason for strong phenotypic correlations within ionome. Adjustment of element concentrations for the effect of variation in phosphorus and sulfur seed content resulted in drastic change of phenotypic correlations between the elements. The genetic architecture of wheat grain ionome was characterized by quantitative trait loci (QTL) analysis using a cross between durum and wild emmer wheat. QTL analysis of the adjusted traits and two-trait analysis of the initial traits paired with either P or S considerably improved QTL detection power and accuracy, resulting in the identification of 105 QTLs and 617 QTL effects for 11 elements. Candidate gene search revealed some potential functional associations between QTLs and corresponding genes within their intervals. Thus, we have shown that accounting for variation in P and S is crucial for understanding of the physiological and genetic regulation of mineral composition of wheat grain ionome and can be implemented for other plants.

Blocked synthesis of sporopollenin and jasmonic acid leads to pollen wall defects and anther indehiscence in genic male sterile wheat line 4110S at high temperatures.

Environment-sensitive genic male sterility is a valid tool for hybrid production and hybrid breeding, but there are no previous reports of the molecular mechanism of fertility conversion. In this study, RNA-seq, phenotypic and cytological observations, and physiological indexes were applied to analyze thermo-sensitive genic male sterility line 4110S under different temperature conditions to explore the fertility transformation mechanism. In total, 3420 differentially expressed genes (DEGs) were identified comprising 2331 upregulated genes and 1089 downregulated genes. The DEGs were apparently distributed among 54 Gene Ontology functional groups. The phenylpropanoid, long-chain fatty acid, and jasmonic acid (JA) biosynthesis pathways were related to male sterility, where their downregulation blocked the synthesis of sporopollenin and JA. Phenotypic and cytological analyses showed that pollen wall defects and anther indehiscence at high temperatures induced sterility. Moreover, enzyme-linked immunosorbent assay results indicated that the abundance of JA was lower in 4110S under restrictive conditions (high temperature) than permissive conditions (low temperature). A possible regulated network of pathways associated with male sterility was suggested. These results provided insights into the molecular mechanism of fertility conversion in the thermosensitive male sterility system.

Cellular and physiological responses to drought stress in Aegilops tauschii genotypes.

Drought stress is one of the most important limiting factors in crop yield through impact on the cellular and physiological functions of the plant. Therefore, the study of physiological responses of plants can help to better understanding the drought tolerance mechanisms. In this experiment, 125 wild diploid wheat genotypes of Aegilops tauschii were evaluated for the physiological responses under rainfed and supplemental irrigation conditions. The physiological characteristics such as leaf relative water content (RWC), excised leaf water retention (ELWR), relative water loss (RWL), chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, ion leakage, membrane stability index (MSI) and proline content were measured. The results showed that the higher proline content, lower chlorophyll degradation rate and low amount of the membrane stability index (MSI) may inhibit the grain yield reduction under rainfed conditions. It was also found that the lower ion leakage due to the low cell membrane damage may led to the higher yield under rain-fed conditions. The results of regression analysis in both rainfed and supplemental irrigation conditions showed that proline content and total chlorophyll were introduced into the model, and explained the most variation in the grain yield. So, considering the above traits, the genotypes 16, 22, 43, 66 and 106 seems to be more drought tolerant and could be exploited in wheat breeding programs after further assessments.

Physiological and developmental traits associated with the grain yield of winter wheat as affected by phosphorus fertilizer management.

Although researchers have determined that attaining high grain yields of winter wheat depends on the spike number and the shoot biomass, a quantitative understanding of how phosphorus (P) nutrition affects spike formation, leaf expansion and photosynthesis is still lacking. A 3-year field experiment with wheat with six P application rates (0, 25, 50, 100, 200, and 400 kg P ha-1) was conducted to investigate this issue. Stem development and mortality, photosynthetic parameters, dry matter accumulation, and P concentration in whole shoots and in single tillers were studied at key growth stages for this purpose. The results indicated that spike number contributed the most to grain yield of all the yield components in a high-yielding (>8 t/ha) winter wheat system. The main stem (MS) contributed 79% to the spike number and tiller 1 (T1) contributed 21%. The 2.7 g kg-1 tiller P concentration associated with 15 mg kg-1 soil Olsen-P at anthesis stage led to the maximal rate of productive T1s (64%). The critical shoot P concentration that resulted in an adequate product of Pn and LAI was identified as 2.1 g kg-1. The thresholds of shoot P concentration that led to the maximum productive ability of T1 and optimal canopy photosynthetic capacity at anthesis were very similar. In conclusion, the thresholds of soil available P and shoot P concentration in whole plants and in single organs (individual tillers) were established for optimal spike formation, canopy photosynthetic capacity, and dry matter accumulation. These thresholds could be useful in achieving high grain yields while avoiding excessive P fertilization.

Nitrogen availability prevents oxidative effects of salinity on wheat growth and photosynthesis by up-regulating the antioxidants and osmolytes metabolism, and secondary metabolite accumulation.

BACKGROUND: Salinity is one of the damaging abiotic stress factor. Proper management techniques have been proposed to considerably lower the intensity of salinity on crop growth and productivity. Therefore experiments were conducted to assess the role of improved nitrogen (N) supplementation on the growth and salinity stress tolerance in wheat by analyzing the antioxidants, osmolytes and secondary metabolites. RESULTS: Salinity (100 mM NaCl) stress imparted deleterious effects on the chlorophyll and carotenoid synthesis as well as the photosynthetic efficiency. N supplementation resulted in increased photosynthetic rate, stomatal conductance and internal CO2 concentration with effects being much obvious in seedlings treated with higher N dose. Under non-saline conditions at both N levels, protease and lipoxygenase activity reduced significantly reflecting in reduced oxidative damage. Such effects were accompanied by reduced generation of toxic radicals like hydrogen peroxide and superoxide, and lipid peroxidation in N supplemented seedlings. Antioxidant defence system was up-regulated under saline and non-saline growth conditions due to N supplementation leading to protection of major cellular processes like photosynthesis, membrane structure and function, and mineral assimilation. Increased osmolyte and secondary metabolite accumulation, and redox components in N supplemented plants regulated the ROS metabolism and NaCl tolerance by further strengthening the antioxidant mechanisms. CONCLUSIONS: Findings of present study suggest that N availability regulated the salinity tolerance by reducing Na uptake and strengthening the key tolerance mechanisms.

Application of Rice Grain Husk Derived Biochar in Ameliorating Toxicity Impacts of Cu and Zn on Growth, Physiology and Enzymatic Functioning of Wheat Seedlings.

Livestock and poultry manure containing high levels of copper and zinc have led to contamination of farmland and products which could have an impact on human health. Biochar is an inexpensive and efficient heavy metal absorbent. In the present study, we have used biochar to mitigate the effects of heavy metals on the growth of wheat seedlings. The study showed that the effects of heavy metals on wheat seedlings growth were mitigated by increasing exposure to biochar. Compared to the control group, the germination potential, germination rate, germination index and vigor index of wheat seedlings with supplemented biochar increased significantly. Moreover, the specific activity of catalase, peroxidase, superoxide dismutase decreased and chlorophyll contents increased, which promote wheat growth and suggests that the addition of biochar could reduce the effects of heavy metals on wheat seedlings.

Effect of salinity stress on bioactive compounds and antioxidant activity of wheat microgreen extract under organic cultivation conditions.

This study was conducted to confirm the effects of salinity stress on bioactive compounds and antioxidant activity of wheat microgreen extract. The microgreens were cultivated for 8 days in organic media with different concentrations of Na [0 (control), 12.5, 25, 50, and 100 mM from sodium chloride] which was contained in a growth chamber with controlled temperature (20/15 °C, day/night), light (14/10 h, light/dark; intensity 150 µmol·m-2·s-1 with quantum dot light-emitting diodes), and humidity (60%). Treatment with increasing concentrations of Na resulted in an increase in the Na content of microgreens. Treatment with 12.5 mM of NaCl significantly maximized ß-carotene (1.21 µg/mL), phenolic acid (41.70 µg/mL), flavonoid (165.47 µg/mL), and vitamin C (29.51 µg/mL) levels and the nitrite-scavenging activities (37.33%) in wheat microgreen extracts. In addition, the salt-stress caused due to treatment with 25 mM of NaCl resulted in the highest anthocyanin (51.43 µg/mL), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (89.31%), and 2,2-diphenyl-1-picrylhydrazyl (63.28%) radical-scavenging activity. Therefore, attaining adequate levels of salt-stress may be useful for the industrial manufacturing of new products from wheat microgreen extract.

Cloning of a COBL gene determining brittleness in diploid wheat using a MapRseq approach.

Plant tissue brittleness is related to cellular structure and lodging. MED0031 is a mutant identified previously from ethyl methane sulfonate treatment of diploid wheat accession TA2726, showing brittleness in both stem and leaf. In microscopic and histological observations, the mutant was found to have less large vascular bundles per unit area, a thinner sclerenchyma cell wall, and a broader parenchyma, compared with the wild type. The mutated gene, TmBr1, was mapped to a 0.056 cM interval on chromosome 5Am. This gene was cloned using a MapRseq approach that searched the candidate gene through combination of the prior target gene mapping information with SNP calling and discovery of differentially expressed genes from RNA_seq data of the wild type and a BC3F2 bulk showing the mutant phenotype. TmBr1 encodes a COBL protein and a nonsense mutation within the region coding for the conserved COBRA domain caused premature translation termination. Introduction of TmBr1 to Arabidopsis AtCOBL4 mutant rescued the phenotype, demonstrating their functional conservation. Apart from the effect on cellulose content, the TmBr1 mutation might modulate synthesis of noncellulosic polysaccharide pectin as well. Application of the MapRseq approach to isolation of genes present in recombination cold spots and complicated genomes was discussed.

Molybdenum-induced effects on photosynthetic efficacy of winter wheat (Triticum aestivum L.) under different nitrogen sources are associated with nitrogen assimilation.

Different nitrogen (N) sources have been reported to significantly affect the photosynthesis (Pn) and its attributes. However, molybdenum (Mo) induced effects on photosynthetic efficacy of winter wheat under different N sources have not been investigated. A hydroponic study was carried out comprising of two winter wheat cultivars '97003' and '97014' as Mo-efficient and Mo-inefficient, respectively to underpin the effects of Mo supply (0 and 1 µM) on photosynthetic efficacy of winter wheat under different N sources (NO3̶, NH4NO3 or NH4+). The results revealed that Mo-induced increases in dry weight, gas exchange parameters, chlorophyll contents, NR activities, NO3̶ assimilation, total N contents and transcripts of TaNR and TaNRT1.1 genes under different N sources followed the trend of NH4NO3 > NO3̶ > NH4+, suggesting that Mo has more complementary effects to nitrate nutrition than sole ammonium. Interestingly, under Mo-deprivation environments, cultivar '97003' recorded more pronounced alterations in Mo-dependent parameters than '97014' cultivar. Moreover, Mo application significantly improved the chlorophyll contents and chloroplast configuration in all N sources showing that Mo has a key role in chlorophyll biosynthesis and chloroplast integrity. The results also highlighted that Mo-induced enhancements in total N contents and photosynthetic characteristics followed the same order as NH4NO3 > NO3- > NH4+, suggesting that Mo might affect Pn through N metabolism. In crux, our study findings imply that Mo supply increased Pn not only through chlorophyll synthesis and chloroplast configuration but also by N uptake and assimilation which may represent a strategy of Mo fertilizer to strengthen the photosynthetic machinery.