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植物学顶尖杂志 Plant Cell, New Phytol , Mol Plant, Plant Physiol, Plant Biotechnol J, Plant J, nature Plants及综合期刊Nucleic Acids Res. ， PNAS，NB，NC及NG有关植物学的研究文章导读，每日定时更新，了解行业最前沿进展。
The importance of wheat as a food crop makes it a major target for agricultural improvements. As one of the most widely grown cereal grains, together with maize and rice, wheat is the leading provider of calories in the global diet, constituting 29% of global cereal production in 2015. In the last few decades, however, yields have plateaued, suggesting that the green revolution, at least for wheat, might have run its course and that new sources of genetic variation are urgently required. The overall aim of our work is to identify novel variation that may then be used to enable the breeding process. As landraces are a potential source of such diversity, here we have characterised the A.E. Watkins Collection alongside a collection of elite accessions using two complementary high-density and high-throughput genotyping platforms. While our results show the importance of using the appropriate SNP collection to compare diverse accessions, they also show that the Watkins Collection contains a substantial amount of novel genetic diversity which has either not been captured in current breeding programmes or which has been lost through previous selection pressures. As a consequence of our analysis, we have identified a number of accessions which carry an array of novel alleles along with a number of interesting chromosome rearrangements which confirm the variable nature of the wheat genome.
Although starch degradation has been well studied in model systems such as Arabidopsis leaves and cereal seeds, this process in starchy fruits during ripening, especially in bananas, is largely unknown. In this study, 38 genes encoding starch degradation-related proteins were identified and characterized from banana fruit. Expression analysis revealed that 27 candidate genes were significantly induced during banana fruit ripening, with concomitant conversion of starch-to-sugars. Furthermore, iTRAQ-based proteomics experiments identified 18 starch degradation-associated enzymes bound to the surface of starch granules, of which 10 were markedly up-regulated during ripening. More importantly, a novel bHLH transcription factor, MabHLH6, was identified based on a yeast one-hybrid screening using MaGWD1 promoter as a bait. Transcript and protein levels of MabHLH6 were also increased during fruit ripening. Electrophoretic mobility shift assays, chromatin immunoprecipitation and transient expression experiments confirmed that MabHLH6 activates the promoters of 11 starch degradation-related genes, including MaGWD1, MaLSF2, MaBAM1,MaBAM2, MaBAM8, MaBAM10, MaAMY3, MaAMY3C, MaISA2, MaISA3, and MapGlcT2-2 by recognizing their E-box (CANNTG) motifs present in the promoters. Collectively, these findings suggest that starch degradation during banana fruit ripening may be attributed to the complex actions of numerous enzymes related to starch breakdown at transcriptional and translational levels, and that MabHLH6 may act as a positive regulator of this process via direct activation of a series of starch degradation-related genes.
Gossypium hirsutum is an allotetraploid with a complex genome. Most genes have multiple copies that belong to At and Dt subgenomes. Sequence similarity is also very high between gene homologs. To efficiently achieve site/gene-specific mutation is quite needed. Due to its high efficiency and robustness, the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/Cas9 system has exerted broad site-specific genome editing from prokaryotes to eukaryotes. In this study, we utilized a CRISPR/Cas9 system to generate two sgRNAs in a single vector to conduct multiple sites genome editing in allotetraploid cotton. An exogenously transformed gene Discosoma red fluorescent protein2(DsRed2)and an endogenous gene GhCLA1 were chosen as targets. The DsRed2 edited plants in T0 generation reverted its traits to wild type, with vanished red fluorescence the whole plants. Besides, the mutated phenotype and genotype were inherited to their T1 progenies. For the endogenous gene GhCLA1, 75% of regenerated plants exhibited albino phenotype with obvious nucleotides and DNA fragments deletion. The efficiency of gene editing at each target site is 66.7% to 100% .The mutation genotype were checked for both genes with Sanger sequencing. Barcode-based high-throughput sequencing, which could be highly efficient for genotyping to a population of mutants, was conducted in GhCLA1 edited T0 plants and it matched well with Sanger sequencing results. No off-target editing was detected at the potential off-target sites. These results proves that the CRISPR/Cas9 system is highly efficient and reliable for allotetraploid cotton genome editing.
Maize is a globally important food, feed crop and raw material for the food and energy industry. Plant architecture optimization plays important roles in maize yield improvement. PIN-FORMED (PIN) proteins are important for regulating auxin spatio-temporal asymmetric distribution in multiple plant developmental processes. In this study, ZmPIN1a overexpression in maize increased the number of lateral roots and inhibited their elongation, forming a developed root system with longer seminal roots and denser lateral roots. ZmPIN1a overexpression reduced plant height, internode length and ear height. This modification of the maize phenotype increased the yield under high density cultivation conditions, and the developed root system improved plant resistance to drought, lodging and a low-phosphate environment. IAA concentration, transport capacity determination and application of external IAA indicated that ZmPIN1a overexpression led to increased IAA transport from shoot to root. The increase in auxin in the root enabled the plant to allocate more carbohydrates to the roots, enhanced the growth of the root, and improved plant resistance to environmental stress. These findings demonstrate that maize plant architecture can be improved by root breeding to create an ideal phenotype for further yield increases.
Lateral Organ Boundaries Domain (LBD) proteins are plant-specific transcription factors playing crucial roles in growth and development. However, the function of LBD proteins in Eucalyptus grandis remains largely unexplored. In the present study, LBD genes in E. grandis were identified and characterized using bioinformatics approaches. Gene expression patterns in various tissues and the transcriptional responses ofEgLBDs to exogenous hormones were determined by qRT-PCR. Functions of the selected EgLBDs were studied by ectopically overexpressing in a hybrid poplar (Populus alba × Populus glandulosa). Expression levels of genes in the transgenic plants were investigated by RNA-seq. Our results showed that there were forty-sixEgLBD members in the E. grandis genome and three EgLBDs displayed xylem- (EgLBD29) or phloem-preferential expression (EgLBD22 and EgLBD37). Confocal microscopy indicated that EgLBD22, EgLBD29 and EgLBD37 were localized to the nucleus. Furthermore, we found that EgLBD22, EgLBD29 and EgLBD37 were responsive to the treatments of indol-3-acetic acid and gibberellic acid. More importantly, we demonstratedEgLBDs exerted different influences on secondary growth. Namely, 35S::EgLBD37 led to significantly increased secondary xylem, 35S::EgLBD29 led to greatly increased phloem fiber production, and 35S::EgLBD22 showing no obvious effects. We revealed that key genes related to gibberellin, ethylene and auxin signaling pathway as well as cell expansion were significantly up- or down-regulated in transgenic plants. Our new findings suggest that LBD genes in E. grandis play important roles in secondary growth. This provides new mechanisms to increase wood or fiber production.
Amylose content (AC) is a key quality trait in rice. A cross between Oryza glaberrima (African rice) and Oryza sativa (Asian rice) segregating for AC was analyzed by sequencing bulks of individuals with high and low AC. SNP associated with the granule bound starch synthase (GBSS1) locus on chromosome 6 were polymorphic between the bulks. In particular a G/A SNP that would result in an Asp to Asn mutation was identified. This amino acid substitution may be responsible for differences in GBSS activity as it is adjacent to a disulphide linkage conserved in all grass GBSS proteins. Other polymorphisms in genomic regions closely surrounding this variation may be the result of linkage drag. In addition to the variant in the starch biosynthesis gene, SNP on chromosomes 1 and 11 linked to AC were also identified. SNP were found in the genes encoding the NACand CCAAT-HAP5 transcription factors that have previously been linked to starch biosynthesis. This study has demonstrated that the approach of sequencing bulks was able to identify genes on different chromosomes associated with this complex trait.
Moso bamboo is a large, woody bamboo with the highest ecological, economic, and cultural value of all the bamboo types and accounts for up to 70% of the total area of bamboo grown. However, the spatio-temporal variation role of moso bamboo shoot during growth period is still unclear. We found that the bamboo shoot growth can be divided into three distinct periods, including winter growth, early growth, and late growth based on gene expression and anatomy. In the early growth period, lateral buds germinated from the top of the bamboo joint in the shoot tip. Intercalary meristems grew vigorously during the winter growth period and early growth period, but in the late growth period, mitosis in the intercalary meristems decreased. The expression of cell cycle-associated genes and the quantity of differentially-expressed genes (DGEs) were higher in early growth than that in late growth, appearing to be influenced by hormonal concentrations. Gene expression analysis indicates that hormone signaling genes play key roles in shoot growth, while auxin signaling genes play a central role. In situ hybridization analyses illustrate how auxin signaling genes regulates apical dominance, meristem maintenance, and lateral bud development. Our study provides a vivid picture of the dynamic changes in anatomy and gene expression during shoot growth in Moso bamboo, and how hormone signaling-associated genes participate in moso bamboo shoot growth.
Physico-chemical properties of storage starch largely determine rice grain quality and food characteristics. Therefore, modification of starch property is effective to fine-tune cooked rice textures. To obtain new resources with modified starch property as breeding materials, we screened a mutant population of ajaponica cultivar Nipponbare and found two independent mutant lines, altered gelatinization (age) 1 and age2, with moderate changes in starch gelatinization property. A combination of conventional genetic analyses and the latest mapping method, MutMapPlus, revealed that both of these lines harbor novel independent mutant alleles of starch branching enzyme IIb (BEIIb) gene. In age1, amino acid substitution of Met-723 to Lys completely abolished BEIIb enzyme activity without significant reduction of its protein level. A transposon insertion in an intron of BEIIb gene reduced BEIIb protein level and activity in age2. Production of a series of the mutant lines by combining age alleles and indica-type starch synthase IIa allele established stepwise alteration of the physico-chemical properties of starch including apparent amylose content, thermal property, digestibility by α-amylase, and branched structures of amylopectin. Consistent with the alteration of starch properties, the results of a sensory evaluation test demonstrated that warm cooked rice of the mutants showed a variety of textures without marked reduction of overall palatability. These results suggest that a series of the mutant lines are capable of manipulation of cooked rice textures.
Engineered minichromosomes could be stably inherited and serves as a platform for simultaneously transferring and stably expressing multiple genes. Chromosomal truncation mediated by repeats of telomeric sequence is a promising approach for the generation of minichromosomes. In the present work, direct repetitive sequences of Arabidopsis telomere were used to study telomere-mediated truncation of chromosomes in Brassica napus. Transgenes containing alien Arabidopsis telomere were successfully obtained, and Southern blotting and fluorescence in situ hybridization (FISH) results show that the transgenes successfully resulted in chromosomal truncation in B. napus. In addition, truncated chromosomes were inherited at rates lower than that predicted by Mendelian rules. To determine the potential manipulations and applications of the engineered chromosomes, such as the stacking of multiple transgenes, the Cre/lox and FRT/FLP recombination systems, both amenable for genetic manipulations through site-specific recombination in somatic cells, were tested for their ability to undergo recombination in B. napus. These results demonstrate that alien Arabidopsis telomere are able to mediate chromosomal truncation in B. napus. This technology would be feasible for chromosomal engineering and for studies on chromosome structure and function in B. napus.
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