BackgroundThe yield of wheat (Triticum aestivum L.), an important crop, is adversely affected by heat stress in many regions of the world. However, the molecular mechanisms underlying thermotolerance are largely unknown.ResultsA novel ferritin gene, TaFER, was identified from our previous heat stress-responsive transcriptome analysis of a heat-tolerant wheat cultivar (TAM107). TaFER was mapped to chromosome 5B and named TaFER-5B. Expression pattern analysis revealed that TaFER-5B was induced by heat, polyethylene glycol (PEG), H2O2 and Fe-ethylenediaminedi(o-hydroxyphenylacetic) acid (Fe-EDDHA). To confirm the function of TaFER-5B in wheat, TaFER-5B was transformed into the wheat cultivar Jimai5265 (JM5265), and the transgenic plants exhibited enhanced thermotolerance. To examine whether the function of ferritin from mono- and dico-species is conserved, TaFER-5B was transformed into Arabidopsis, and overexpression of TaFER-5B functionally complemented the heat stress-sensitive phenotype of a ferritin-lacking mutant of Arabidopsis. Moreover, TaFER-5B is essential for protecting cells against heat stress associated with protecting cells against ROS. In addition, TaFER-5B overexpression also enhanced drought, oxidative and excess iron stress tolerance associated with the ROS scavenging. Finally, TaFER-5B transgenic Arabidopsis and wheat plants exhibited improved leaf iron content.ConclusionsOur results suggest that TaFER-5B plays an important role in enhancing tolerance to heat stress and other abiotic stresses associated with the ROS scavenging.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0958-2) contains supplementary material, which is available to authorized users.

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BackgroundIn upland cotton (Gossypium hirsutum L.), genotypes with the same mature fiber length (FL) might possess different genes and exhibit differential expression of genes related to fiber elongation at different fiber developmental stages. However, there is a lack of information on the genetic variation influencing fiber length and its quantitative trait loci (QTLs) during the fiber elongation stage. In this study, a subset of upland cotton accessions was selected based on a previous GWAS conducted in China and grown in multiple environments to determine the dynamic fiber length at 10, 15, 20, and 25 days post-anthesis (DPA) and maturity. The germplasm lines were genotyped with the Cotton 63 K Illumina single-nucleotide polymorphism (SNP) array for GWAS.ResultsA total of 25, 38, 57, 89 and 88 SNPs showed significant correlations with fiber length at 10, 15, 20 and 25 DPA and maturity, respectively. In addition, 60 more promising SNPs were detected in at least two tests and two FL developmental time points, and 20 SNPs were located within the confidence intervals of QTLs identified in previous studies. The fastest fiber-length growth rates were obtained at 10 to 15 DPA in 69 upland cotton lines and at 15 to 20 DPA in 14 upland cotton accessions, and 10 SNPs showed significant correlations with the fiber-length growth rate. A combined transcriptome and qRT-PCR analysis revealed that two genes (D10G1008 and D13G2037) showed differential expression between two long-fiber genotypes and two short-fiber genotypes.ConclusionsThis study provides important new insights into the genetic basis of the time-dependent fiber-length trait and reveals candidate SNPs and genes for improving fiber length in upland cotton.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-5309-2) contains supplementary material, which is available to authorized users.

BackgroundSmall auxin-up RNA (SAUR) gene family is the largest family of early auxin response genes in higher plants, which have been implicated in the regulation of multiple biological processes. However, no comprehensive analysis of SAUR genes has been reported in cotton (Gossypium spp.).ResultsIn the study, we identified 145, 97, 214, and 176 SAUR homologous genes in the sequenced genomes of G. raimondii, G. arboreum, G. hirsutum, and G. barbadense, respectively. A phylogenetic analysis revealed that the SAUR genes can be classified into 10 groups. A further analysis of chromosomal locations and gene duplications showed that tandem duplication and segmental duplication events contributed to the expansion of the SAUR gene family in cotton. An exon-intron organization and motif analysis revealed the conservation of SAUR-specific domains, and the auxin responsive elements existed in most of the upstream sequences. The expression levels of 16 GhSAUR genes in response to an exogenous application of IAA were determined by a quantitative RT-PCR analysis. The genome-wide RNA-seq data and qRT-PCR analysis of selected SAUR genes in developing fibers revealed their differential expressions. The physical mapping showed that 20 SAUR genes were co-localized with fiber length quantitative trait locus (QTL) hotspots. Single nucleotide polymorphisms (SNPs) were detected for 12 of these 20 genes between G. hirsutum and G. barbadense, but no SNPs were identified between two backcross inbred lines with differing fiber lengths derived from a cross between the two cultivated tetraploids.ConclusionsThis study provides an important piece of genomic information for the SAUR genes in cotton and lays a solid foundation for elucidating the functions of SAUR genes in auxin signaling pathways to regulate cotton growth.Electronic supplementary materialThe online version of this article (10.1186/s12864-017-4224-2) contains supplementary material, which is available to authorized users.

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Wheat (Triticum aestivum L.) yield and quality are adversely affected by heat, drought, or the combination of these two stresses in many regions of the world. A phosphoenolpyruvate carboxylase kinase-related kinase gene, TaPEPKR2, was identified from our previous heat stress-responsive transcriptome analysis of heat susceptible and tolerant wheat cultivars. Based on the wheat cultivar Chinese Spring genome sequence, TaPEPKR2 was mapped to chromosome 5B. Expression analysis revealed that TaPEPKR2 was induced by heat and polyethylene glycol treatment. To analyze the function of TaPEPKR2 in wheat, we transformed it into the wheat cultivar Liaochun10, and observed that the transgenic lines exhibited enhanced heat and dehydration stress tolerance. To examine whether TaPEPKR2 exhibits the same function in dicotyledonous plants, we transformed it into Arabidopsis, and found that its overexpression functionally enhanced tolerance to heat and dehydration stresses. Our results imply that TaPEPKR2 plays an important role in both heat and dehydration stress tolerance, and could be utilized as a candidate gene in transgenic breeding.

Conditions that disrupt protein folding, such as heat stress, can overwhelm the capacity of cells to fold proteins, thus causing endoplasmic reticulum (ER) stress. In Arabidopsis thaliana and other plants, inositol-requiring enzyme-1 mediated unconventional splicing of bZIP60 plays a crucial role in the heat and ER stress responses. However, little is known about this pathway in wheat (Triticum aestivum), especially its importance in heat tolerance. Here, we found that heat stress induced upregulation and unconventional splicing of TabZIP60 occurred in wheat seedlings. Constitutive expression of the spliced form of TabZIP60 (TabZIP60s) enhanced heat tolerance in Arabidopsis, but overexpression of the unspliced form (TabZIP60u) did not. RNA-sequencing analysis revealed ER stress related genes involved in heat responses in TabZIP60s-overexpression transgenic Arabidopsis. Chromatin immunoprecipitation-qPCR showed that TabZIP60s directly binds to 17 target genes including AtbZIP60. Also, the 26S proteasome pathway post-translationally regulates TabZIP60s levels during heat stress responses. Our findings suggest that unconventional splicing of TabZIP60 could contribute to heat tolerance in transgenic plants by modulating the expression of ER stress-related genes.

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