ZmbZIP27 regulates nitrogen-mediated leaf angle by modulating lignin deposition in maize

In grain crops such as maize(Zea mays),leaf angle(LA)is a key agronomic trait affecting light interception and thus planting density and yield.Nitrogen(N)affects LA in plants,but we lack a good understanding of how N regulates LA.Here,we report that N deficiency enhanced lignin deposition in the ligular region of maize seedlings.In situ hybridization showed that the bZIP transcription factor gene ZmbZIP27 is mainly expressed in the phloem of maize vascular bundles.Under N-sufficient conditions,transgenic maize overexpressing ZmbZIP27 showed significantly smaller LA compared with wild type(WT).By contrast,zmbzip27_(ems)mutant showed larger LA under both N-deficient and N-sufficient conditions compared with WT.Overexpression of ZmbZIP27 enhanced lignin deposition in the ligular region of maize in the field.We further demonstrated that ZmbZIP27 could directly bind the promoters of the microRNA genes ZmMIR528a and ZmMIR528b and negatively regulate the expression levels of ZmmiR528.ZmmiR528 knockdown transgenic maize displayed erect architecture in the field by increasing lignin content in the ligular region of maize.Taken together,these results indicate that ZmbZIP27 regulates N-mediated LA size by regulating the expression of ZmmiR528 and modulating lignin deposition in maize.

Identification and Validation of a Major Quantitative Trait Locus for Slow-rusting Resistance to Stripe Rust in Wheat

Stripe （yellow） rust, caused by Puccinia striiformis Westend. f. sp. tritici Eriks （Pst）, is one of the most important wheat （Triticum aestivum L.） diseases and causes significant yield losses. A recombinant inbred （RI） population derived from a cross between Yanzhan 1 and Xichang 76-9 cultivars was evaluated for resistance to wheat stripe rust strain CYR32 at both the seedling and adult plant stages. Four resistance quantitative trait loci （QTLs） were detected in this population, in which the major one, designated as Yrql, was mapped on chromosome 2DS. The strategy of using the Brachypodium distachyon genome, wheat expressed sequence tags and a draft DNA sequences （scaffolds） of the D-genome （Aegilops tauschfi Coss.） for the development of simple sequence repeat （SSR） markers was successfully used to identify 147 SSRs in hexaploid wheat. Of the 19 polymorphic SSRs in the RI population, 17 SSRs were mapped in the homeologous group 2 chromosomes near Yrql region and eight SSRs were genetically mapped in the 2.7 cM region of Yrql, providing abundant DNA markers for fine-mapping of Yrql and marker-assisted selection in wheat breeding program. The effectiveness of Yrql was validated in an independent population, indicating that this resistance QTL can be successfully transferred into a susceptible cultivar for improvement of stripe rust resistance.

Nitrogen supply affects ion homeostasis by modifying root Casparian strip formation through the miR528-LAC3 module in maize

Although nitrogen(N)is known to affect mineral element homeostasis in plants,the molecular mechanisms of interactions between N and other nutrients remain largely unclear.Wereport here that N supply affects ion homeostasis inmaize.Berberine hemisulfate staining and a propidiumiodide penetration assay showed that N luxury significantly delayed Casparian strip(CS)formation in maize roots.We further demonstrated that N-mediated CS formation in maize was independent of RBOHF-activated H2O2 production.N luxury induced the expression of ZmmiR528 inwhole roots and root tips.Knockdown and loss-of-function ofZmmiR528 promoted CS formation under both N-luxury and N-deficient conditions.Both ZmMIR528a and ZmMIR528b contribute to early CS formation under different N conditions.RNA-seq and real-time RT-PCR analysis demonstrated that ZmLAC3,but not ZmLAC5,responded to N treatments.Consistent with results obtained with ZmmiR528 TM transgenic maize and mir528a/b loss-of-function mutants,transgenic maize overexpressing ZmLAC3 displayed early CS formation under different N conditions.Under field conditions,K,Ca,Mn,Cu,Mg,and Zn concentrations were greater in the ear leaf of ZmLAC3-overexpressing transgenicmaize than in the wild type.These results indicate that ZmmiR528 affects CS formation in maize by regulating the expression of ZmLAC3,and modification of CS formation has the potential to improve maize quality.

A review of multiscale expansion of low permeability reservoir cracks

The study of rock crack propagation by multi-scale method is of great significance to comprehensively and accurately understand the law of rock crack evolution.In this paper,the theoretical,experimental and numerical methods from macroscale,mesoscale and microscale used for crack propagation in recent years are summarized and analyzed.Firstly,the evolution mechanism of the crack and the related research status are analyzed from a single scale.Secondly,multi-scale theory,modeling,meshing algorithm and macro-mesoscopic parameters are reviewed in the multi-scale coupling method.Through the analysis of the results published in recent years,it is considered that the following aspects need to be further studied:the characteristic parameters of the rock are different at different scales,so the extraction of the characteristic parameters under different scales is essential to modeling and coupling;the heterogeneity of rock and the prefabrication of cracks are greatly affected by human factors,so that 3D printing will be a good breakthrough to build the model of crack owing to its accurate control on the distribution and the size of cracks.The internal stress field of the rock is complex and varied,and the generation and expansion of the microcracks in the process of crack propagation are closely related to the surrounding environment.Therefore,it is of great importance to combine theoretical,experimental and numerical research with practical engineering.