The Contributions of Sub-Communities to the Assembly Process and Ecological Mechanisms of Bacterial Communities along the Cotton Soil-Root Continuum Niche Gradient.

Soil microbes are crucial in shaping the root-associated microbial communities. In this study, we analyzed the effect of the soil-root niche gradient on the diversity, composition, and assembly of the bacterial community and co-occurrence network of two cotton varieties. The results revealed that the bacterial communities in cotton soil-root compartment niches exhibited a skewed species abundance distribution, dominated by abundant taxa showing a strong spatial specificity. The assembly processes of the rhizosphere bacterial communities were mainly driven by stochastic processes, dominated by the enrichment pattern and supplemented by the depletion pattern to recruit bacteria from the bulk soil, resulting in a more stable bacterial community. The assembly processes of the endosphere bacterial communities were determined by processes dominated by the depletion pattern and supplemented by the enrichment pattern to recruit species from the rhizosphere, resulting in a decrease in the stability and complexity of the community co-occurrence network. The compartment niche shaped the diversity of the bacterial communities, and the cotton variety genotype was an important source of diversity in bacterial communities within the compartment niche. We suggest that the moderate taxa contribute to significantly more changes in the diversity of the bacterial community than the rare and abundant taxa during the succession of bacterial communities in the cotton root-soil continuum.

Genetic architecture and candidate gene identification for grain size in bread wheat by GWAS.

Grain size is a key trait associated with bread wheat yield. It is also the most frequently selected trait during domestication. After the phenotypic characterization of 768 bread wheat accessions in three plots for at least two years, the present study shows that the improved variety showed significantly higher grain size but lower grain protein content than the landrace. Using 55K SNP assay genotyping and large-scale phenotyping population and GWAS data, we identified 5, 6, 6, and 6 QTLs associated with grain length, grain weight, grain area, and thousand grain weight, respectively. Seven of the 23 QTLs showed common association within different locations or years. Most significantly, the key locus associated with grain length, qGL-2D, showed the highest association after years of multi-plot testing. Haplotype and evolution analysis indicated that the superior allele of qGL-2D was mainly hidden in the improved variety rather than in landrace, which may contribute to the significant difference in grain length. A comprehensive analysis of transcriptome and homolog showed that TraesCS2D02G414800 could be the most likely candidate gene for qGL-2D. Overall, this study presents several reliable grain size QTLs and candidate gene for grain length associated with bread wheat yield.

Identification and expression profiles of the YABBY transcription factors in wheat.

BACKGROUND: YABBY is a plant-specific transcription factor (TF) that belongs to the zinc finger protein superfamily and is composed of a C2-C2 domain at the N-terminus and a YABBY domain at the C-terminus. It plays a role in plant development and growth. METHODS: In this study, 20 YABBY TFs were identified in the wheat genome. Phylogenetic relationships, collinearity relationships, gene structures, conserved motifs, and expression patterns were analyzed. RESULTS: Twenty TaYABBY TFs were distributed unevenly on 15 chromosomes. Collinearity analysis showed that these genes have a close relationship with monocot plants. The phylogenetic tree of wheat YABBYs classified these TaYABBYs into FIL, YAB2, INO, and CRC clades. Gene structure and conserved motif analyses showed that they share similar components in the same clades. Expression profile analysis showed that many TaYABBY genes have high expression levels in leaf tissues and are regulated by abiotic stresses, especially salt stress. Our results provide a basis for further functional characterization of the YABBY gene family.

QTL mapping of root traits in wheat under different phosphorus levels using hydroponic culture.

BACKGROUND: Phosphorus (P) is an important in ensuring plant morphogenesis and grain quality, therefore an efficient root system is crucial for P-uptake. Identification of useful loci for root morphological and P uptake related traits at seedling stage is important for wheat breeding. The aims of this study were to evaluate phenotypic diversity of Yangmai 16/Zhongmai 895 derived doubled haploid (DH) population for root system architecture (RSA) and biomass related traits (BRT) in different P treatments at seedling stage using hydroponic culture, and to identify QTL using 660 K SNP array based high-density genetic map. RESULTS: All traits showed significant variations among the DH lines with high heritabilities (0.76 to 0.91) and high correlations (r = 0.59 to 0.98) among all traits. Inclusive composite interval mapping (ICIM) identified 34 QTL with 4.64-20.41% of the phenotypic variances individually, and the log of odds (LOD) values ranging from 2.59 to 10.43. Seven QTL clusters (C1 to C7) were mapped on chromosomes 3DL, 4BS, 4DS, 6BL, 7AS, 7AL and 7BL, cluster C5 on chromosome 7AS (AX-109955164 - AX-109445593) with pleiotropic effect played key role in modulating root length (RL), root tips number (RTN) and root surface area (ROSA) under low P condition, with the favorable allele from Zhongmai 895. CONCLUSIONS: This study carried out an imaging pipeline-based rapid phenotyping of RSA and BRT traits in hydroponic culture. It is an efficient approach for screening of large populations under different nutrient conditions. Four QTL on chromosomes 6BL (2) and 7AL (2) identified in low P treatment showed positive additive effects contributed by Zhongmai 895, indicating that Zhongmai 895 could be used as parent for P-deficient breeding. The most stable QTL QRRS.caas-4DS for ratio of root to shoot dry weight (RRS) harbored the stable genetic region with high phenotypic effect, and QTL clusters on 7A might be used for speedy selection of genotypes for P-uptake. SNPs closely linked to QTLs and clusters could be used to improve nutrient-use efficiency.

Transcriptome analysis reveals differentially expressed MYB transcription factors associated with silicon response in wheat.

Silicon plays a vital role in plant growth. However, molecular mechanisms in response to silicon have not previously been studied in wheat. In this study, we used RNA-seq technology to identify differentially expressed genes (DEGs) in wheat seedlings treated with silicon. Results showed that many wheat genes responded to silicon treatment, including 3057 DEGs, of which 6.25% (191/3057) were predicted transcription factors (TFs). Approximately 14.67% (28 out of 191) of the differentially expressed TFs belonged to the MYB TF family. Gene ontology (GO) enrichment showed that the highly enriched DEGs were responsible for secondary biosynthetic processes. According to KEGG pathway analysis, the DEGs were related to chaperones and folding catalysts, phenylpropanoid biosynthesis, and protein processing in the endoplasmic reticulum. Moreover, 411 R2R3-MYB TFs were identified in the wheat genome, all of which were classified into 15 groups and accordingly named S1-S15. Among them, 28 were down-regulated under silicon treatment. This study revealed the essential role of MYB TFs in the silicon response mechanism of plants, and provides important genetic resources for breeding silicon-tolerant wheat.

Salt-responsive transcriptome analysis of triticale reveals candidate genes involved in the key metabolic pathway in response to salt stress.

Triticale is tolerant of many environmental stresses, especially highly resistant to salt stress. However, the molecular regulatory mechanism of triticale seedlings under salt stress conditions is still unclear so far. In this study, a salt-responsive transcriptome analysis was conducted to identify candidate genes or transcription factors related to salt tolerance in triticale. The root of salt-tolerant triticale cultivars TW004 with salt-treated and non-salt stress at different time points were sampled and subjected to de novo transcriptome sequencing. Total 877,858 uniquely assembled transcripts were identified and most contigs were annotated in public databases including nr, GO, KEGG, eggNOG, Swiss-Prot and Pfam. 59,280, 49,345, and 85,922 differentially expressed uniquely assembled transcripts between salt treated and control triticale root samples at three different time points (C12_vs_T12, C24_vs_T24, and C48_vs_T48) were identified, respectively. Expression profile and functional enrichment analysis of DEGs found that some DEGs were significantly enriched in metabolic pathways related to salt tolerance, such as reduction-oxidation pathways, starch and sucrose metabolism. In addition, several transcription factor families that may be associated with salt tolerance were also identified, including AP2/ERF, NAC, bHLH, WRKY and MYB. Furthermore, 14 DEGs were selected to validate the transcriptome profiles via quantitative RT-PCR. In conclusion, these results provide a foundation for further researches on the regulatory mechanism of triticale seedlings adaptation to salt stress in the future.

Genome-wide identification and expression profiles of ERF subfamily transcription factors in Zea mays.

The Ethylene-Response Factor (ERF) subfamily transcription factors (TFs) belong to the APETALA2/Ethylene-Responsive Factor (AP2/ERF) superfamily and play a vital role in plant growth and development. However, identification and analysis of the ERF subfamily genes in maize have not yet been performed at genome-wide level. In this study, a total of 76 ERF subfamily TFs were identified and were found to be unevenly distributed on the maize chromosomes. These maize ERF (ZmERF) TFs were classified into six groups, namely groups B1 to B6, based on phylogenetic analysis. Synteny analysis showed that 50, 54, and 58 of the ZmERF genes were orthologous to those in rice, Brachypodium, and Sorghum, respectively. Cis-element analysis showed that elements related to plant growth and development, hormones, and abiotic stress were identified in the promoter region of ZmERF genes. Expression profiles suggested that ZmERF genes might participate in plant development and in response to salinity and drought stresses. Our findings lay a foundation and provide clues for understanding the biological functions of ERF TFs in maize.

[Effects of seeding pattern and phosphorus application on population structure, photosynthe-tic characteristics and yield of winter wheat]. / æ’­ç§æ–¹å¼å’Œæ–½ç£·å¯¹å†¬å°éº¦ç¾¤ä½“ç»“æž„ã€å ‰åˆç‰¹æ€§å’Œäº§é‡çš„å½±å“.

Under Xinjiang winter wheat seeding pattern, in order to sort out proper phosphorus application (PA) and find out the effects and mechanism of PA on population structure, photosynthesis characteristics and yield and provide reliable evidence for PA management of winter wheat, we arranged a two-factor complete split-plot design of wheat variety "Xindong 22". The main area consisted of two seeding ways: drill seeding pattern (D) and uniform seeding pattern (U), while in the sub-area there were four levels of PA(P2O5): 0, 60, 120, and 180 kg·hm-2(represented by P0, P60, P120 and P180 for those treatments, respectively). The results showed that the earbearing percentage in U was 15.9% higher than that in D, and the other features (PAR interception rate, extinction coefficient, leaf area index, SPAD and photosynthetic parameters) were more optimal in 120 kg·hm-2 treatment. Our results showed that the 120 kg·hm-2 treatment in U would be the optimal option with respect to population structure, photosynthetic characteristics, and yield.

A cupin domain is involved in α-amylase inhibitory activity.

Proteinaceous α-amylase inhibitors have specialized activities that make some strong inhibition of α-amylases. New α-amylase inhibitors continue to be discovered so far. A proteinaceous α-amylase inhibitor CL-AI was isolated and identified from chickpea seeds. CL-AI, encoded by Q9SMJ4, was a storage legumin precursor containing one α-chain and one ß-chain, and each chain possessed a same conserved cupin domain. Amino acid mutation and deficiency of cupin domain would lead to loss of α-amylase inhibitory activity, indicating that it was essential for inhibitory activity. CL-AI(α + ß) in its single stranded state in vivo had inhibitory activity. After it was processed into one α-chain and one ß-chain, the two chains were connected to each other via disulfide bond, which would cover the cupin domains and lead to the loss of inhibitory activity. The CL-AI(α + ß), α-chain and ß-chain could inhibit various α-amylases and delay the seed germination of wheat, rice and maize as well as the growth and development of potato beetle larva. Two cupin proteins, Glycinin G1 in soybean and Glutelinin in rice were also found to have inhibitory activity. Our results indicated that the cupin domain is involved in α-amylase inhibitory activity and the proteins with a cupin domain may be a new kind of proteinaceous α-amylase inhibitor.

[Diversity of endophytic fungi associated with Ferula sinkiangensis K. M. Shen].

OBJECTIVE: We studied the diversity of endophytic fungi associated with Ferula sinkiangensis K. M. Shen. METHOD: Endophytic fungi from different years (1-2 years, 3-4 years and > 5 years) and different parts (root, stemand leaf) of Ferula sinkiangensis K. M. Shen were isolated by tissue expand method. Strains were classified by morphology and similarity of internal transcribed spacer (ITS) sequence by Clustal X method. Composition, diversity and preference of endophytic fungal community were analyzed by the isolation rate (IR), isolation frequency (IF), Shannon-Wiener biodiversity index (H'), Margalef Richness index (R). RESULTS: In total 140 endophytic fungi were isolated from F. sinkiangensis K. M. Shen and classified into 18 genera. Among the 140 isolates, Aureobasidium (25.7%), Alternaria (16.4%) and Phyllosticta (15.7%) were the dominant genera. The isolation results show that there were some notable differences between distribution and composition of the endophytic fungi isolated from different years and different parts of Ferula sinkiangensis K. M. Shen. Meanwhile, a certain degree of years and tissue preference were also obvious. CONCLUSION: The results obtained in this study will be helpful to exploit the endophytic fungal resources of Ferula sinkiangensis K. M. Shen, which can also provide a new way for the realization of the artificial breeding of Ferula sinkiangensis K. M. Shen.

Transcriptional responses to drought stress in root and leaf of chickpea seedling.

Chickpea (Cicer arietinum L.) is an important pulse crop grown mainly in the arid and semi-arid regions of the world. Due to its taxonomic proximity with the model legume Medicago truncatula and its ability to grow in arid soil, chickpea has its unique advantage to understand how plant responds to drought stress. In this study, an oligonucleotide microarray was used for analyzing the transcriptomic profiles of unigenes in leaf and root of chickpea seedling under drought stress, respectively. Microarray data showed that 4,815 differentially expressed unigenes were either ≥ 2-fold up- or ≤ 0.5-fold down-regulated in at least one of the five time points during drought stress. 2,623 and 3,969 unigenes were time-dependent differentially expressed in root and leaf, respectively. 110 pathways in two tissues were found to respond to drought stress. Compared to control, 88 and 52 unigenes were expressed only in drought-stressed root and leaf, respectively, while nine unigenes were expressed in both the tissues. 1,922 function-unknown unigenes were found to be remarkably regulated by drought stress. The expression profiles of these time-dependent differentially expressed unigenes were useful in furthering our knowledge of molecular mechanism of plant in response to drought stress.

Molecular cloning and characterization of an F-box family gene CarF-box1 from chickpea (Cicer arietinum L.).

F-box protein family has been found to play important roles in plant development and abiotic stress responses via the ubiquitin pathway. In this study, an F-box gene CarF-box1 (for Cicer arietinum F-box gene 1, Genbank accession no. GU247510) was isolated based on a cDNA library constructed with chickpea seedling leaves treated by polyethylene glycol. CarF-box1 encoded a putative protein with 345 amino acids and contained no intron within genomic DNA sequence. CarF-box1 is a KFB-type F-box protein, having a conserved F-box domain in the N-terminus and a Kelch repeat domain in the C-terminus. CarF-box1 was localized in the nucleus. CarF-box1 exhibited organ-specific expression and showed different expression patterns during seed development and germination processes, especially strongly expressed in the blooming flowers. In the leaves, CarF-box1 could be significantly induced by drought stress and slightly induced by IAA treatment, while in the roots, CarF-box1 could be strongly induced by drought, salinity and methyl jasmonate stresses. Our results suggest that CarF-box1 encodes an F-box protein and may be involved in various plant developmental processes and abiotic stress responses.

Identification and characterization of a LEA family gene CarLEA4 from chickpea (Cicer arietinum L.).

Late-embryogenesis abundant (LEA) proteins have been reported to be closely correlated with the acquisition of desiccation tolerance during seed development and response of plant to drought, salinity, and freezing, etc. In this study, a LEA gene, CarLEA4 (GenBank accession no. GU247511), was isolated from chickpea based on a cDNA library constructed with chickpea seedling leaves treated by polyethylene glycol (PEG). CarLEA4 contained two exons and one intron within genomic DNA sequence and encoded a putative polypeptide of 152 amino acids. CarLEA4 had a conserved pfam domain, and showed high similarity to the group 4 LEA proteins in secondary structure. It was localized in the nucleus. The transcripts of CarLEA4 were detected in many chickpea organs including seedling leaves, stems, roots, flowers, young pods, and young seeds. CarLEA4 was inhibited by leaf age and showed expression changes in expression during seed development, pod development and germination. Furthermore, the expression of CarLEA4 was strongly induced by drought, salt, heat, cold, ABA, IAA, GA(3) and MeJA. Our results suggest that CarLEA4 encodes a protein of LEA group 4 and may be involved in various plant developmental processes and abiotic stress responses.