高温对杂交水稻籽粒灌浆和剑叶某些生理特性的影响

以杂交籼稻特优559为材料,探讨了高温胁迫对水稻灌浆期剑叶中有关生理特性和籽粒灌浆速率的影响.结果表明:高温胁迫加速了剑叶叶绿素的丧失,使SOD活性明显降低,质膜透性和MDA含量明显增加,脯氨酸、AsA、GSH、可溶性蛋白质以及可溶性糖含量明显降低,籽粒灌浆速率和籽粒重下降.高温使灌浆期水稻叶片衰老加速、光合能力下降是其导致灌浆速率、结实率、粒重和籽粒产量降低的主要生理原因.     

结实期土壤水分亏缺影响水稻籽粒灌浆的生理原因

通过分析结实期土壤水分亏缺对水稻(Oryza sativa)籽粒中蔗糖向淀粉合成的生理代谢中关键酶活性及籽粒灌浆的调节作用, 探讨土壤水分亏缺影响水稻籽粒灌浆的生理机制。结果表明, 适度土壤水分亏缺诱导了灌浆高峰期(花后15-20天)水稻籽粒中蔗糖合成酶、腺苷二磷酶葡萄糖焦磷酸化酶、可溶性淀粉合成酶及淀粉分支酶活性的增加, 提高了籽粒灌浆中前期(花后10-20天)籽粒中淀粉积累速率和籽粒灌浆速率。但在灌浆后期(花后20-30天)籽粒中, 上述关键酶活性下降较快, 籽粒活跃灌浆期明显缩短, 灌浆前中期灌浆速率的增加不能完全补偿灌浆期缩短带来的同化物积累损失, 导致水分亏缺处理水稻籽粒充实不良, 结实率、籽粒重和产量显著降低。研究认为, 灌浆期土壤水分亏缺引起的灌浆后期籽粒中蔗糖向淀粉合成代谢中一些关键酶活性快速下降和籽粒内容物的供应不足是籽粒淀粉积累总量减少、粒重降低的主要生理原因。     

氮、硫肥与灌浆后期高温胁迫对小麦籽粒产量和品质的影响

灌浆期高温胁迫通常导致小麦籽粒产量降低、品质变差.为了探索有效缓解高温胁迫不利影响的有效措施,在大田条件下,以济麦20为试验材料,运用后期高温棚增温的方法,研究了氮、硫肥与灌浆后期高温对小麦籽粒产量和品质的影响.结果表明:高温处理后小麦千粒质量、籽粒产量显著降低(19.7%～28.3%),蛋白质含量升高,蛋白质组分中不溶性谷蛋白含量下降,可溶性谷蛋白含量上升,面团形成时间和稳定时间缩短;氮肥追施比例由50%增加到70%,非高温处理的籽粒产量无显著变化,不溶性谷蛋白质含量和谷蛋白聚合指数(不溶性谷蛋白含量/可溶性谷蛋白含量)升高,面团形成时间和稳定时间延长;高温处理的千粒质量和籽粒产量因氮肥追施比例提高而提高(2.07%～3.58%),面团形成时间和稳定时间缩短;不论高温处理还是非高温处理,与追施硫肥相比,硫肥基施提高籽粒产量、谷蛋白聚合指数,延长面团形成时间和稳定时间;为了有效缓解灌浆后期高温对小麦籽粒产量和品质的不利影响,硫肥基施、氮肥施用基追比50%:50%是较为适宜的施肥模式.     

氮肥基追比与灌浆中期高温胁迫对小麦产量和品质的影响

以优质强筋小麦品种‘济麦20’为供试材料,研究了不同氮肥基追比（基肥：追肥为1：1、1：2、1：5）和灌浆中期高温胁迫对小麦籽粒产量和品质的影响.结果显示,灌浆中期高温胁迫处理能显著降低小麦千粒重、籽粒产量以及籽粒的淀粉含量、支链淀粉含量、支链淀粉/直链淀粉比例,峰值粘度、稀懈值、最终粘度也相应降低,而籽粒蛋白质含量相应提高,导致淀粉品质变劣而面团的流变学特性得以改善;在基追比例1：1的基础上增大拔节期氮素追施比例,能显著提高小麦常温和高温胁迫下籽粒产量,缓解高温胁迫对小麦千粒重和籽粒产量的不良影响,而对小麦籽粒面团流变学特性及面粉的粘度指标影响甚微.研究表明,适当提高拔节期氮肥追施比例可有效减缓灌浆中期高温胁迫对小麦产量的负面影响,但对小麦籽粒品质影响较小.     

稻米直链淀粉含量的形成及其与灌浆结实期温度的关系

通过多类型品种的田间分期番种和人工气候箱控温处理等试验,对稻米直链淀粉含量（Ａｍｙｌｏｓｅ ｃｏｎｔｅｎｔ,简称ＡＣ）的形成动态变化特征及灌浆结实期温度的影响效应进行了分析。结果表明：水稻灌浆结实过程中稻米ＡＣ的形成动态变化过程叮嘱一次或二次曲线进行模拟,灌浆初期籽粒中的ＡＣ值很低,随之急剧上升,至２０～３０ｄ左右达到最大值,然后ＡＣ的变化基本趋于稳定;稻米ＡＣ的形成变化与籽粒于物质积累过程喑存在     

温度对小麦碳氮代谢、产量及品质影响

 摘 要 环境温度的变化影响植物的碳氮代谢过程,从而改变植物的生长发育。综述了小麦光合产物形成、叶片蔗糖合成、茎鞘中非结构碳水化合物合成与降解、籽粒淀粉合成的一般规律及其在不同温度条件下所发生的变化,指出了小麦灌浆期温度超过30 ℃后粒重和产量将会降低。小麦品质主要由胚乳中面筋蛋白的特性决定,从小麦籽粒蛋白质形成、含量、组分等方面分析了其与灌浆期温度的关系,根据面筋蛋白特性的变化,认为高温胁迫对小麦烘烤品质会产生不利影响。同时全球气候变暖可能加重小麦灌浆期的高温危害,提出了今后相关研究中将要出现的3个热点问题：1）CO2浓度升高和温度升高协同作用对小麦产量和品质的影响,2）小麦耐热性的生理机制及其栽培调控措施,3）筛选小麦耐热基因及选育耐热新品种。     

灌浆期高温对水稻光合特性、内源激素和稻米品质的影响

以2个籼稻品种:温度钝感型品种K30和温度敏感型品种R21为材料,利用人工气候室控温,在水稻灌浆期设置高温(日均温度34.9℃)和适温(日均温度28.0℃)处理,测定不同灌浆时期(5,10,15,20,25d和30d)光合特性、内源激素含量及稻米品质的变化。结果表明,高温增强了K30的光合能力,K30高温处理净光合速率(Pn)在整个灌浆期都明显高于对照;R21在灌浆前期(5、10d和15d)高温处理与适温处理Pn差异不明显,在灌浆后期(20、25d和30d)高温处理Pn下降。高温增加了K30叶片和籽粒脱落酸(ABA)含量;而R21高温处理和适温处理叶片与籽粒ABA含量的对比不明显。高温处理对两个水稻品种叶片和籽粒赤霉素(GA3)与生长素(IAA)含量也有不同程度影响。高温胁迫降低稻米品质,但K30比R21表现出更强的温度钝感特性。     

结实期相对高温对稻米淀粉粘滞性谱及镁、钾含量的影响

选用武育粳3号(粳稻)和扬稻6号(籼稻)两个水稻品种,利用人工气候室在水稻灌浆结实期进行控温试验,设置全结实期相对高温、结实前期相对高温、结实后期相对高温、全结实期适温(对照,日均温23 ℃)对照4个处理,探讨结实期不同时段相对高温(日均温度-30 ℃)对稻米淀粉粘滞性谱和Mg、K等元素含量的影响.结果表明：结实期相对高温使武育粳3号和扬稻6号淀粉粘滞性谱特征值发生改变,其中糊化开始温度、冷胶粘度、回复值和消减值升高,最高粘度、热浆粘度和崩解值下降;结实期相对高温促进了米粉中Mg、K、N含量的提高,特别是K含量的大幅提高,使稻米中Mg/K和Mg/(N·AC·K)明显降低;而2个水稻品种的直链淀粉含量（AC）对相对高温的反应截然相反,武育粳3号的AC降低、扬稻6号的AC升高.全结实期相对高温对稻米淀粉粘滞性谱和Mg、K等元素含量的影响最大,结实前期其次,结实后期的影响较小,开花后20 d内是稻米淀粉粘滞性谱和Mg、K等元素含量受温度影响的关键时期.Mg/K和Mg/(N·AC·K)与淀粉粘滞性谱特征值显著相关,可以作为稻米食味品质评价的参考指标.     

水稻中硅的营养功能及生理机制的研究进展

尽管硅还没有被列为植物生长的必需营养元素,但它在水稻生长发育、产量与品质形成、矿质营养吸收以及逆境生理等方面都具有重要的作用。硅不仅是水稻细胞结构成分和组成物质,还参与调节水稻各种生理生化代谢过程,促进光合作用,改善冠层结构,增强抗倒伏能力,提高群体质量,促进产量、品质和肥料吸收利用效率的协同提高。硅通过物理途径或生理生化途径增强水稻对重金属、盐渍、干旱、紫外线、高温等非生物胁迫以及病虫生物胁迫的抵抗力。还展望了水稻中硅研究的未来发展。     

灌溉对干旱区冬小麦干物质积累、分配和产量的影响

为探明灌溉对干旱区冬小麦(Triticum aestivum)产量、水分利用效率(WUE)、干物质积累及分配等的影响, 以甘肃河西走廊冬小麦适宜种植品种‘临抗2号’为材料进行了研究。在冬季灌水180 mm的条件下, 生育期以灌水量和灌水次数等共设置5个处理, 分别为: 拔节期灌水量165 mm (W1)、拔节期灌水量120 mm +抽穗期灌水量105 mm (W2)、拔节期灌水量105 mm +抽穗期灌水量105 mm +灌浆期灌水量105 mm (W3)、拔节期灌水量75 mm +抽穗期灌水量75 mm +灌浆期灌水量75 mm (W4)、拔节期灌水量105 mm +抽穗期灌水量75 mm +灌浆期灌水量45 mm (W5)。结果表明: 随着生育期的推进, 土壤有效含水量(AWC)受灌水次数及灌水量影响更加明显; W3、W4处理的土壤各层AWC在灌浆期均较高; 叶面积指数(LAI)下降慢, 延缓了生育后期的衰老; 生育后期干物质积累增加, 提高了穗粒数、千粒重和籽粒产量。籽粒产量以W3处理最高, 但W4具有最高的WUE, 且籽粒产量与W3无显著差异, 但W4较灌溉总量相同的W2和W5以及灌水量最少的W1具有明显的指标优势。W1、W2、W5处理灌浆期各层土壤AWC均较低, 花后LAI下降快, 干物质积累减少, 灌浆持续期缩短, 穗粒数和千粒重减少, 最终表现为籽粒产量和WUE下降。灌浆期水分胁迫可促进花前储存碳库向籽粒的再转运, 并随着干旱胁迫的加重而提高, 对籽粒产量起补偿作用; 水分胁迫提高了灌浆速率, 但缩短了灌浆持续期。相关性分析表明, 灌浆持续期、有效灌浆持续期、有效灌浆期粒重增加值和最大籽粒灌浆速率出现时间与千粒重和籽粒产量均呈正相关。综合考虑, 拔节、抽穗及灌浆期各灌溉75 mm是高产高WUE的最佳灌水方案。     

Genetic engineering of rice to resist rice tungro disease

Rice tungro disease (RTD), caused by the co-infection of rice tungro bacilliform virus (RTBV) and rice tungro spherical virus, is one of the most important viral diseases of rice in South and Southeast Asia. The disease remains one of the major threats to sustainable rice production in many countries. The lack of resistance genes to RTBV—the causal agent of tungro disease—makes it even more difficult to manage RTD. In this review, we summarize previous and current research efforts to genetically engineer rice in order to increase the crop’s resistance to tungro disease, including the use of pathogen-derived resistance and of host genes that confer RTD resistance and/or that restrict feeding by the insect vector. The prospects of developing rice cultivars with durable resistance to RTD are also discussed.     

田埂留草控制稻飞虱效果及对捕食性天敌多样性影响

为探讨稻田田埂保留杂草控制稻飞虱的效果及对捕食性天敌多样性的影响,以稻田田埂周年性保留杂草为处理,以稻田田埂不保留杂草为对照,对处理区和对照区稻田稻飞虱成若虫、捕食性天敌种类和数量进行系统调查和分析。结果表明,在调查期内(6—10月),田埂留草稻田百丛稻株稻飞虱数量为(891.11±133.12)头,较非留草稻田减少35.31%;田埂留草稻田捕食性天敌隶属5目23科35种,而田埂非留草稻田隶属5目21科33种;田埂非留草稻田捕食性天敌优势种为食虫沟瘤蛛Ummeliata insecticepsBoes.etStr.、拟水狼蛛Pirata subpiraticus Boes.etStr.和黑肩绿盲蝽Cyrtorrhinus livdipennis Reuter,而田埂留草后优势种为食虫沟瘤蛛U.insecticeps、草间小黑蛛Erigonidium graminicolum(Sundevall)、拟水狼蛛和拟环纹狼蛛Lycosa pseudoamulata(Bose.etStr.);田埂留草稻田捕食性天敌的个体数量、丰富度、多样性指数分别为(128.89±13.52)、(33.67±0.50)、(4.53±0.04)头/百丛,较田埂非留草稻田分别增加31.96%、25.73%、5.59%,而优势度指数和均匀性指数没有显著变化。研究结果为发展稻田景观多样化控害提供依据。     

Identification of rice genes induced in a rice blast-resistant mutant

To clarify mechanisms of rice blast resistance in rice plants we used suppression subtractive hybridization (SSH) to isolate genes induced upon rice blast inoculation in a rice blast-resistant mutant. A total of 26 rice cDNAs were isolated and found to have elevated expression upon rice blast infection in a rice blast-resistant derivative, SHM-11, of the rice cultivar, Sanghaehyanghyella. Sequencing of the cDNAs revealed that many of the proteins they encoded had been previously described as involved in plant responses against pathogen attack. Two interesting groups of the defense-related proteins consisted of three different PR5 homologues and four different protease inhibitors, all highly expressed in the rice blast mutant. Genes encoding proteins involved in signal transduction and regulation were also identified, including translation initiation factor eIF5A, C2 domain DNA binding protein, putative rice EDS and putative receptor like kinase. Most of the identified cDNAs were highly expressed 24 h after blast inoculation. Our results suggest that a pathway regulating defense gene expression may be altered in the mutant, resulting in early induction of the defense genes upon fungal infection.     

Characterization of rice mutants with enhanced susceptibility to rice blast

As a first step towards identifying genes involving in the signal transduction pathways mediating rice blast resistance, we isolated 3 mutants lines that showed enhanced susceptibility to rice blast KJ105 (91-033) from a T-DNA insertion library of the japonica rice cultivar, Hwayeong. Since none of the susceptible phenotypes co-segregated with the T-DNA insertion we adapted a map-based cloning strategy to isolate the gene(s) responsible for the enhanced susceptibility of the Hwayeong mutants. A genetic mapping population was produced by crossing the resistant wild type Hwayeong with the susceptible cultivar, Nagdong. Chi-square analysis of the F2 segregating population indicated that resistance in Hwayeong was controlled by a single major gene that we tentatively named Pi-hy. Randomly selected susceptible plants in the F2 population were used to build an initial map of Pi-hy. The SSLP marker RM2265 on chromosome 2 was closely linked to resistance. High resolution mapping using 105 F2 plants revealed that the resistance gene was tightly linked, or identical, to Pib, a resistance gene with a nucleotide binding sequence and leucine-rich repeats (NB-LRR) previously isolated. Sequence analysis of the Pib locus amplified from three susceptible mutants revealed lesions within this gene, demonstrating that the Pi-hy gene is Pib. The Pib mutations in 1D-22-10-13, 1D-54-16-8, and 1C-143-16-1 were, respectively, a missense mutation in the conserved NB domain 3, a nonsense mutation in the 5th LRR, and a nonsense mutation in the C terminus following the LRRs that causes a small deletion of the C terminus. These findings provide evidence that NB domain 3 and the C terminus are required for full activity of the plant R gene. They also suggest that alterations of the resistance gene can cause major differences in pathogen specificity by affecting interactions with an avirulence factor.     

产大米蛋白水解酶的菌株筛选、酶学性质及制备大米寡肽

【目的】旨在分离、筛选并鉴定具有大米蛋白降解作用的菌株及其关键蛋白酶,为高效制备大米寡肽提供制备酶及最优制备条件。【方法】以"水解圈"为评价指标,从粮食仓库附近土壤筛选获得具有降解大米蛋白能力的菌株;通过16S rRNA序列分析确定菌株归属;利用单因素实验获得最佳氮源并初步分析酶学性质;利用HPLC检测寡肽得率,并对制备条件进一步优化。【结果】经鉴定具有大米蛋白降解作用的菌株为沙雷氏菌(Serratia sp. JWG-D15),以大米蛋白为氮源培养菌株JWG-D15,蛋白酶So PRO产量最高,其最适温度40℃,最适pH 8.0;在加酶量20 U/mg,大米蛋白浓度40 mg/mL,40℃,4 h条件下寡肽得率最高72.38%。【结论】以大米蛋白为氮源培养菌株JWG-D15,蛋白酶So PRO产量最高;蛋白酶So PRO制得的大米寡肽,其得率是目前行业最高。本研究既丰富了大米寡肽的制备用酶的种类,又为深入大米寡肽产业化提供一定理论基础。     

Occurrence of D-serine in rice and characterization of rice serine racemase

Germinated, unpolished rice was found to contain a substantial amount of D-serine, with the ratio of the D-enantiomer to the L-enantiomer being higher for serine than for other amino acids. The relative amount of D-serine (D/(D + L)%) reached approximately 10% six days after germination. A putative serine racemase gene (serr, clone No. 001-110-B03) was found in chromosome 4 of the genomic DNA of Oryza sativa L. ssp. Japonica cv. Nipponbare. This was expressed as serr in Escherichia coli and its gene product (SerR) was purified to apparent homogeneity. SerR is a homodimer with a subunit molecular mass of 34.5 kDa, and is highly specific for serine. In addition to a serine racemase reaction, SerR catalyzes D- and L-serine dehydratase reactions, for which the specific activities were determined to be 2.73 and 1.42 nkatal/mg, respectively. The optimum temperature and pH were respectively determined for the racemase reaction (35 °C and pH 9.0) and for the dehydratase reaction (35 °C and pH 9.5). SerR was inhibited by PLP-enzyme inhibitors. ATP decreased the serine racemase activity of SerR but increased the serine dehydratase activity. Kinetic analysis showed that Mg²⁺ increases the catalytic efficiency of the serine racemase activity of SerR and decreases that of the serine dehydratase activity. Fluorescence-quenching analysis of the tryptophan residues in SerR indicated that the structure of SerR is distorted by the addition of Mg²⁺, and this structural change probably regulates the two enzymatic activities.     

Dynamic viscoelasticity of protease-treated rice batters for gluten-free rice bread making

Papain (cysteine protease), subtilisin (Protin SD-AY10, serine protease), and bacillolysin (Protin SD-NY10, metallo protease) increased the specific volume of gluten-free rice breads by 19–63% compared to untreated bread. In contrast, Newlase F (aspartyl protease) did not expand the volume of the rice bread. In a rheological analysis, the viscoelastic properties of the gluten-free rice batters also depended on the protease categories. Principal component analysis (PCA) analysis suggested that the storage and loss moduli (G′ and G″, respectively) at 35 °C, and the maximum values of G′ and G″, were important factors in the volume expansion. Judging from the PCA of the viscoelastic parameters of the rice batters, papain and Protin SD-AY10 improved the viscoelasticity for gluten-free rice bread making, and Protin SD-NY effectively expanded the gluten-free rice bread. The rheological properties differed between Protin SD-NY and the other protease treatments.     

Recent advances in rice biotechnology--towards genetically superior transgenic rice

Rice biotechnology has made rapid advances since the first transgenic rice plants were produced 15 years ago. Over the past decade, this progress has resulted in the development of high frequency, routine and reproducible genetic transformation protocols for rice. This technology has been applied to produce rice plants that withstand several abiotic stresses, as well as to gain tolerance against various pests and diseases. In addition, quality improving and increased nutritional value traits have also been introduced into rice. Most of these gains were not possible through conventional breeding technologies. Transgenic rice system has been used to understand the process of transformation itself, the integration pattern of transgene as well as to modulate gene expression. Field trials of transgenic rice, especially insect-resistant rice, have recently been performed and several other studies that are prerequisite for safe release of transgenic crops have been initiated. New molecular improvisations such as inducible expression of transgene and selectable marker-free technology will help in producing superior transgenic product. It is also a step towards alleviating public concerns relating to issues of transgenic technology and to gain regulatory approval. Knowledge gained from rice can also be applied to improve other cereals. The completion of the rice genome sequencing together with a rich collection of full-length cDNA resources has opened up a plethora of opportunities, paving the way to integrate data from the large-scale projects to solve specific biological problems.