THE GLOBAL LIPSCHITZ SOLUTION FOR A PEELING MODEL

This paper focusses on a peeling phenomenon governed by a nonlinear wave equation with a free boundary.Under the hypotheses that the total variation of the intial data and the boundary data are small,the global existence of a weak solution to the nonlinear problem(1.1)-(1.3)is proven by a modified Glimm scheme.The regularity of the peeling front is established,and the asymptotic behaviour of the obtained solution and the peeling front at infinity is also studied.

Brassinosteroid and gibberellin coordinate rice seed germination and embryo growth by regulating glutelin mobilization

Seed germination is the beginning of a new lifecycle,and involves many complex physiological and biochemical reactions including seed reserve mobilization in the endosperm and nutrient transport and reuse in the embryo.Although glutelin is a dominant storage protein in rice,its contribution to seed germination and its regulatory mechanisms are mostly unknown.Gibberellin (GA) and brassinosteroid (BR),two major growth-promoting phytohormones,also play positive roles in controlling seed germination.However,how GA and BR interact and coordinate seed germination and facilitate glutelin mobilization remains unclear.In the present study,biochemical and physiological analyses of seed germination indicated that both GA and BR promote seed germination and post-germination growth.Exogenous application of GA restored germination defects caused by BR deficiency or insensitivity.Proteomic and q RT-PCR results showed that the expression of several glutelin proteins and their encoding genes was induced by BR and GA in the embryo.Expression assays suggested that the increased accumulation of glutelin protein in the embryo was due to the accelerated degradation of glutelin by a cysteine proteinase (REP-1) in the endosperm.The breakdown of glutelin in the endosperm showed a strict positive correspondence with the length of the shoot.The GluA2 mutation led to reduced degradation rate of glutelin and defects in seed germination,and the promotion effect of GA on seed germination was weakened in the glua2mutant.In vitro culture assay of rice embryos showed that glutelin mobilization functioned downstream of the GA and BR pathways to promote shoot elongation.These findings suggest a mechanism that mediates crosstalk between BR and GA in co-regulating rice seed germination and embryo growth.

Mapping QTLs for Heat Tolerance in Rice (Oryza sativa L. ) at Heading Stage Using Chromosome Segment Substitution Lines

In the present study, a japonica rice （ Oryza sativa L. ） variety Nipponbare, an indica variety 9311 and a set of chromosome segment substitution lines （CSSLs） which were generated using Nipponbare as the recipient parent and 9311 as the donor parent were used as the experimental materials. The CSSLs were grown in 2012 （normal temperature condition） and 2013 （high temperature condition） in Yangzhou, Jiangsu, and were used to map the quantitative trait loci （QTLs） for heat tolerance, based on the heat tolerance index [ （The seed setting rate under normal temperature condition -The seed setting rate under high temper- ature condition） / The seed setting rate under normal temperature condition]. As a result, three QTLs related to heat tolerance in rice were mapped on chromo- somes 2, 4 and 12, respectively. They had LOD （logarithm of rntds） scores of 2.56, 4.02 and 2.79, and contributian rates of 4.95%, 7.99% and 5.44%. Among them, qHT12.1 showed positive effect, while qHT2.1 and qHT4. t showed negative effect on heat tolerance. The results lay a foundation for the fine mapping and cloning of the QTLs and genes related to heat tolerance, and for the breeding of heat-tolerant rice varieties.

Effect and Its Mechanism of Brassinolide-regulated Starch Metabolism in Rice Germination

The study was aimed to explore the effect and mechanism of brassinolide（ BL） regulated starch metabolism in rice endosperm during seed germination.The radicle elongation of rice seeds treated with 1 μmol/L BL was inhibited during germination. The analysis on rice seeds with a GUS-fused promoter showed that BL had different regulatory effects on Wx,SBEI,and AGPS1. The effect of BL treatment on the physicochemical properties of rice starch was further investigated by scanning electron microscopy,Fourier transform infrared spectroscopy,and X-ray diffraction. The results showed that the starch treated with BL maintained better crystallinity and orderly structure,indicating that during the germination process,the degradation of starch in endosperm was slow,which might be one of the reasons for the slow radicle growth in the early stages of seed germination. This study provided important clues for further analysis of the molecular mechanisms underlying BR-regulated rice seed germination.

Generation of selectable marker-free soft transgenic rice with transparent kernels by downregulation of SSSⅡ-2

The amylose content(AC)of rice endosperm starch varies from 0 to 35%,and is associated with rice cooking and eating quality.Soft rice has low AC,generally between 6%and 15%,and its eating quality is high whether it is consumed hot or cold.However,the appearance quality of current soft rice cultivars needs to be improved,especially opaque endosperm.Conventional genetic engineering has improved some agronomic traits of soft rice varieties,but not endosperm appearance.In the present study,a RNAi construct of the soluble starch synthase II-2(SSSII-2)and the hygromycin phosphotransferase(HPT)gene were introduced into an elite japonica rice variety,Kangtiaowuyunjing(KWY8)by co-transformation.Several selectable marker-free(SMF)transgenic lines were obtained,and SSSII-2 expression was significantly downregulated in selected transgenic lines,resulting in lower AC of the endosperm.The physicochemical properties of the transgenic rice kernels,including gel consistency(GC)and rapid visco analyzer(RVA)profile,differed significantly from those of wild-type rice and were similar to those of a soft rice variety,Nanjing 46(NJ46).These findings indicate that the cooking,eating,and processing qualities of transgenic rice are comparable to those of NJ46.However,the transgenic rice endosperm retained a transparent appearance under low-moisture conditions.Thus,SMF SSSII-2 RNAi rice provides a resource for breeding soft rice with transparent endosperm.

A rare Waxy allele coordinately improves rice eating and cooking quality and grain transparency

In rice(Oryza sativa), amylose content(AC) is the major factor that determines eating and cooking quality(ECQ). The diversity in AC is largely attributed to natural allelic variation at the Waxy(Wx)locus. Here we identified a rare Wx allele, Wx^(mw) ,which combines a favorable AC, improved ECQ and grain transparency. Based on a phylogenetic analysis of Wx genomic sequences from 370 rice accessions, we speculated that Wx^(mw) may have derived from recombination between two important natural Wx alleles, Wx^(in) and Wx^(b). We validated the effects of Wx^(mw) on rice grain quality using both transgenic lines and near-isogenic lines(NILs). When introgressed into the japonica Nipponbare(NIP) background, Wx^(mw) resulted in a moderate AC that was intermediate between that of NILs carrying the Wx^(b)allele and NILs with the Wx^(mp) allele. Notably, mature grains of NILs fixed for Wx^(mw) had an improved transparent endosperm relative to soft rice. Further, we introduced Wx^(mw) into a high-yielding japonica cultivar via molecular marker-assisted selection: the introgressed lines exhibited clear improvements in ECQ and endosperm transparency. Our results suggest that Wx^(mw) is a promising allele to improve grain quality, especially ECQ and grain transparency of high-yielding japonica cultivars, in rice breeding programs.

机械球磨改性零价铝的作用机制

零价铝(Zero-valent aluminum,ZVAl)具有良好的延展性和质轻等物理特性以及极低的氧化还原电位等化学特性。在新型轻质高强度复合材料的制备中,ZVAl已被优先考虑作为理想的金属基体;另一方面,作为优良的电子供体,ZVAl被用于产氢领域铝水反应的快速析氢和环境领域污染物的高效去除。机械球磨作为一种操作简单和易于工程化的材料加工新方法,可有效克服传统铝基金属材料制备方法中的混合不均匀及界面结合差等问题;也可有效破坏ZVAl表面的致密氧化膜,促进ZVAl的电子释放。已有研究发现,通过球磨ZVAl与助磨剂,控制研磨强度,可以实现复合材料的均匀分散和良好的界面结合,并伴随有少量的金属间化合物和化学活性物质的生成,获得具有优异材料性能的复合物;另外,通过机械球磨过程中的"切割器"作用,置换、碳化或脱氯等机械化学反应,微观结构的改变,以及水介质中的点蚀作用、原电池效应和副反应的减少等作用机制,可提高产氢量和污染物的去除率。本文综述了利用机械球磨来增强ZVAl基复合材料的机械性能的基本原理,系统总结了ZVAl机械球磨表面改性及其用于产氢和污染物去除时的内在作用,探讨了球磨参数和水化学参数对体系的影响规律,并就值得深入研究的问题进行了展望,以期通过对不同学科相关领域的深入了解,来推动机械球磨改性ZVAl在环境领域的进一步发展。

铁基材料改性零价铝的作用机制及应用

近年来,零价铝(Zero-Valent Aluminum, ZVAl)因其具有极低的氧化还原电位、是优良的电子供体等化学特性,已被广泛地用于水中污染物的去除;但因其表面致密的氧化膜会阻碍其活性释放,并且在反应中表面易形成(氢)氧化物而造成二次钝化,从而导致其反应寿命短。研究表明,零价铁、铁矿石、含铁黏土矿物等铁基材料与ZVAl复合后可克服ZVAl自身的弊端,除了可以改变ZVAl的硬度、磁性等物理性能外,更有意义的是,可以通过:1)加快反应速率、2)拓宽pH范围、3)延长反应持久性、4)增强反应选择性等化学作用机制实现提高其去除水中污染物效能的目的。因此,本文在系统总结不同方法下铁基材料对ZVAl的改性机制(即发生氧化还原反应、金属间的反应或是自蔓延反应)的基础上,重点对该改性作用在去除水中污染物时的增强机制,以及进一步的优化策略(引入第三金属、外加非金属单质、添加聚合物、投加配体和构建负载物等)进行了详细综述;并对铁基材料改性ZVAl后构筑的复合材料值得深入研究的方向进行了展望,以期推动ZVAl水处理新技术在环境领域更深入的研究和更广泛的应用。

miR172-AP2模块调控植物生长发育及逆境响应的研究进展

MicroRNA(miRNA)是一类具有调控能力的非编码小分子RNA,通过与靶基因mRNA特异或非特异性结合,诱导靶基因mRNA降解或抑制其翻译,从而调控植物的生长发育。其中,miR172的靶基因AP2所编码的转录因子为植物所特有,miR172在转录后或翻译水平对AP2进行表达调控,进而调控植物的花发育、时序转换、小穗形态、块茎和果实发育、结瘤(豆科)以及逆境响应等过程。该文综述了近年来miR172-AP2模块在植物生长发育调控方面的最新研究进展。

Wx^lv、the Ancestral Allele of Rice Waxy Gene

In rice grains,the Waxy (Wx) gene is responsible for the synthesis of amylose,the most important determinant for eating and cooking quality.The effects of several Wx alleles on amylose content and the taste of cooked rice have been elucidated.However,the relationship between artificial selection and the evolution of various Wx alleles as well as their distribution remain unclear.Here we report the identification of an ancestral allele,Wx^lv,which dramatically affects the mouthfeel of rice grains by modulating the size of amylose molecules.We demonstrated that WF originated directly from wild rice,and the three major Wx alleles in cultivated rice (Wx^b,Wx^a,and Wx^in) differentiated after the substitution of one base pair at the functional sites.These data indicate that the Wx^lv allele played an important role in artificial selection and domestication.The findings also shed light on the evolution of various Wx alleles,which have greatly contributed to improving the eating and cooking quality of rice.

Starch biosynthesis in cereal endosperms: An updated review over the last decade

Starch is a vital energy source for living organisms and is a key raw material and additive in the food and non-food industries.Starch has received continuous attention in multiple research fields.The endosperm of cereals(e.g.,rice,corn,wheat,and barley)is the most important site for the synthesis of storage starch.Around 2010,several excellent reviews summarized key progress in various fields of starch research,serving as important references for subsequent research.In the past 10 years,many achievements have been made in the study of starch synthesis and regulation in cereals.The present review provides an update on research progress in starch synthesis of cereal endosperms over the past decade,focusing on new enzymes and non-enzymatic proteins involved in starch synthesis,regulatory networks of starch synthesis,and the use of elite alleles of starch synthesis-related genes in cereal breeding programs.We also provide perspectives on future research directions that will further our understanding of cereal starch biosynthesis and regulation to support the rational design of ideal quality grain.