植物科学顶尖文章导读|2月17日

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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

This article does not have an abstract to display.

http://www.cell.com/molecular-plant/abstract/S1674-2052(18)30054-6

Flowering plant (angiosperm) genomes are exceptional in their variability with respect to genome size, ploidy, chromosome number, gene content and gene arrangement. Gene movement, although observed in some of the earliest plant genome comparisons, has been relatively under-investigated. We present herein a description of several interesting properties of plant gene and genome structure that are pertinent to the successful movement of a gene to a new location. These considerations lead us to propose a model that can explain the frequent success of plant gene mobility, namely that Small Insulated Genes Move Around (SIGMAR). The SIGMAR model is then compared to known processes for gene mobilization, and predictions of the SIGMAR model are formulated to encourage future experimentation. The overall results indicate that the frequent gene movement in angiosperm genomes is partly an outcome of the unusual properties of angiosperm genes, especially their small size and insulation from epigenetic silencing.

http://www.cell.com/molecular-plant/abstract/S1674-2052(18)30053-4

The Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR) system has emerged as the revolutionary platform for DNA targeting. This system uses a site-specific RNA guide to direct a CRISPR effector (e.g., Cas9 and Cpf1) to a DNA target. Here, we elaborate a general strategy to simultaneously express multiple guide RNAs (gRNA) and CRISPR RNAs (crRNA) from introns of Cas9 and Cpf1. This method utilizes the endogenous tRNA processing system or crRNA processing activity of Cpf1 to cleave the spliced intron which contains tRNA-gRNA polycistron or crRNA-crRNA array. We demonstrated that the tRNA-gRNA intron is able to fuse with Cas9 as one gene. Such hybrid gene could be expressed using one polymerase II promoter and exhibited high efficiency and robustness to simultaneously targeting multiple sites. We also implemented this strategy in Cpf1-mediated genome editing using intronic tRNA-crRNA and crRNA-crRNA array. Interestingly, hybrid genes containing Cpf1 and intronic crRNA array exhibited remarkably increased efficiency than the conventional Cpf1 vectors. Taken together, this study presents a method to express CRISPR reagents from one hybrid gene to increase genome editing efficiency and capacity. Owing to its simplicity and versatility, this method could be broadly used to develop sophisticated CRISPR tools in eukaryotes.

http://www.cell.com/molecular-plant/abstract/S1674-2052(18)30055-8

This article does not have an abstract to display.

http://www.cell.com/molecular-plant/abstract/S1674-2052(18)30052-2

This article does not have an abstract to display.

http://www.cell.com/molecular-plant/abstract/S1674-2052(18)30051-0

Recognition of the AVRPM3A2/F2 avirulence protein from powdery mildew by the wheat PM3A/F immune receptor induces a hypersensitive response after co-expression in Nicotiana benthamiana. The molecular determinants of this interaction and how they shape natural AvrPm3a2/f2 allelic diversity are unknown.We sequenced the AvrPm3a2/f2 gene in a worldwide collection of 272 mildew isolates. Using the natural polymorphisms of AvrPm3a2/f2 as well as sequence information from related gene family members, we tested 85 single-residue-altered AVRPM3A2/F2 variants with PM3A, PM3F and PM3FL456P/Y458H (modified for improved signaling) in Nicotiana benthamiana for effects on recognition.An intact AvrPm3a2/f2 gene was found in all analyzed isolates and the protein variant recognized by PM3A/F occurred globally at high frequencies. Single-residue alterations in AVRPM3A2/F2mostly disrupted, but occasionally enhanced, the recognition response by PM3A, PM3F and PM3FL456P/Y458H. Residues enhancing hypersensitive responses constituted a protein domain separate from both naturally occurring polymorphisms and positively selected residues of the gene family.These results demonstrate the utility of using gene family sequence diversity to screen residues for their role in recognition. This approach identified a putative interaction surface in AVRPM3A2/F2 not polymorphic in natural alleles. We conclude that molecular mechanisms besides recognition drive AvrPm3a2/f2 diversification.

http://onlinelibrary.wiley.com/doi/10.1111/nph.15026/full

Rapidly determining root growth patterns is biologically important and technically challenging. Current methods focus on direct observation of roots and require destructive excavations or time-consuming root tracing.We developed a novel methodology based on analyzing soil particle displacement, rather than direct observation of roots. This inferred root growth method uses digital image correlation (DIC) analysis, an established and high-throughput method used in many engineering and science disciplines.By applying DIC analyses to repeated images of plants grown in clear window boxes, we produced visually intuitive and quantifiable strain maps, indicating the magnitude and direction of soil movement. From this, we could infer root growth and rapidly quantify root system metrics. Strain measures were closely associated with the spatial distribution of roots and correlated with root length measured using conventional approaches. The method also allowed for the detection of root proliferation in nutrient-enriched soil patches, indicating its suitability for quantifying biological patterns.This novel application of DIC in root biology is effective, scalable, low cost, flexible and complementary to existing technologies. This method offers a new tool for answering questions in plant biology and will be particularly useful in studies involving temporal dynamics of root processes.

http://onlinelibrary.wiley.com/doi/10.1111/nph.15009/full

The Barley stripe mosaic virus (BSMV) γb protein is a viral suppressor of RNA silencing (VSR) and symptom determinant. However, it is unclear how post-translational modification affects the different functions of γb.Here, we demonstrate that γb is phosphorylated at Ser-96 by a PKA-like kinase in vivo and in vitro. Mutant viruses containing a nonphosphorylatable substitution (BSMVS96A or BSMVS96R) exhibited reduced viral accumulation in Nicotiana benthamiana due to transient induction of the cell death response that constrained the virus to necrotic areas. By contrast, a BSMVS96D mutant virus that mimics γb phosphorylation spread similarly to the wild-type virus.Furthermore, the S96A mutant had reduced local and systemic γb VSR activity due to having compromised its binding activity to 21-bp dsRNA. However, overexpression of other VSRs in trans or in cis failed to rescue the necrosis induced by BSMVS96A, demonstrating that suppression of cell death by γb phosphorylation is functionally distinct from its RNA silencing suppressor activitiesThese results provide new insights into the function of γb phosphorylation in regulating RNA silencing and the BSMV-induced host cell death response, and contribute to our understanding of how the virus optimizes the balance between viral replication and virus survival in the host plants during virus infection.

http://onlinelibrary.wiley.com/doi/10.1111/nph.15065/full