根茎禾草乳熟期净光合速率日变化的比较研究

对6种具有不同根茎长度的禾草乳熟期净光合速率日变化进行了比较研究．结果表明,除了中间偃麦草(Elytrigia intermedia)为“单峰”曲线外,另外5种禾草的净光合速率日变化曲线均呈“双峰型”,且其总体趋势是根茎越发达、根冠比越大,其净光合速率越迟到达第1峰、“午降”经历时间也越短,而大气相对湿度偏低(<55％)和叶片温度偏高(>36℃)是导致“午降”的重要因素．羊草(Leymus chinense)、茹莎娜牧冰草(Pascopyrum smithii)、赖草(Leymus secalinus)、大赖草(Leymus racemosus)、蒙古冰草(Agropyron mongolicum)、中间偃麦草(Elytrigia intermedia)的净光合速率第1峰值分别出现在10：12、10：00、9：51、9：39、9：06、8：13;“午降”经历时间分别是471、474、464、467和551min;“午降”期间的叶片温度均值分别是37．8、37．5、36．9、37．0和36．3℃．羊草和蒙古冰草、赖草和大赖草分别具有相似的净光合速率日变化曲线。在P=0．01时,r值分别是0．88和0．96。     

Proteome analysis of male gametophyte development in rice anthers

We used proteomic analysis to investigate the changing patterns of protein synthesis during pollen development in anthers from rice plants grown under strictly controlled growth conditions. Cytological analysis and external growth measurements such as anther length, auricle distances and days before flowering were used to determine pollen developmental stages. This allowed the collection of synchronous anther materials representing six discrete pollen developmental stages. Proteins were extracted from the anther samples and separated by two-dimensional gel electrophoresis to produce proteome maps. The anther proteome maps of different developmental stages were compared and 150 protein spots, which were changed consistently during development, were analysed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry to produce peptide mass fingerprint (PMF) data. Database searches using these PMF data revealed the identities of 40 of the protein spots analyzed. These 40 proteins represent 33 unique gene products. Four protein spots that could not be identified by PMF analysis were analysed by N-terminal microsequencing. Multiple charge-isoforms of vacuolar acid invertase, fructokinase, beta-expansin and profilin were identified. These proteins are closely associated with sugar metabolism, cell elongation and cell expansion, all of which are cell activities that are essential to pollen germination. The existence of multiple isoforms of the same proteins suggests that during the process of pollen development some kind of post-translational modification of these proteins occurs.     

Response of four rice varieties to Rhodobacter capsulatus at seedling stage

The phototrophic purple nonsulphur bacterium (PPNSB) Rhodobacter capsulatus was used to inoculate seedlings of four rice varieties Giza 159, Giza 171, Giza 176 and Giza 181, grown in hydroponic culture with or without nitrogen. After three weeks the seedling growth parameters were measured. Inoculation with R. capsulatus enhanced seedling growth of all rice varieties tested. The response to inoculation as compared to control plants (no nitrogen, no R. capsulatus) were 52% to 75% for shoot height, 47% to 100% for aerial part dry weight, 45% to 78% for aerial part N content, –37% to –9% for maximum root length, –4% to 8% for root system dry weight and 50% to 62% for root N content.     

Proteome analysis and characterization of phenotypes of lesion mimic mutant spotted leaf 6 in rice

Rice spotted leaf 6 (spl6) mutant produces lesions caused by spontaneous cell death in the absence of pathogenic infection. Expression of this genetic trait was developmentally programmed. After the tillering stage, small red and brown lesions were initiated in groups on the leaf blade. Eventually, the lesions formed parallel lines along the midrib of the leaf. Under light and transmission electron microscopy, we observed that thylakoid membranes of mesophyll chloroplasts were progressively damaged in the nonspotted section of the mutant leaf. However, chloroplasts were absent in the mesophyll cells of the spotted area of the spl6 mutant. These results indicated that lesion formation of the spl6 mutant might be caused by oxidative burst. Proteome analysis revealed that 159 protein spots were up or downregulated in comparison between spotted leaves of the spl6 mutant plants and normal leaves of the wild type. Among them, protein disulfide isomerase (PDI), transketolase, thioredoxin peroxidase (TPX), ATP synthase, RuBisCO large subunit, and RuBisCO activase small subunit were not identified in the spl6 mutant but were abundant in the wild type. Especially, the absence of TPX and PDI might be the cause of the failure to protect cells against oxidative burst resulting in degradation of the thylakoid membranes and leading to programmed cell death and lesion development.     

Gibberellin-induced elongation and osmoregulation in internodes of floating rice

Internodal elongation in floating rice ( Oryza sativa L. cv. Habiganj Aman II) is known to be enhanced by treatment with ethylene or gibberellic acid (GA₃) at high relative humidity (RH). However, ethylene-induced internodal elongation is inhibited at low RH. while GA₃-induced internodal elongation is hardly affected by humidity. We examined the possible involvement of osmoregulation in the stimulation by GA₃ of the elongation of internodes at low RH. Submergence and treatment with ethylene or GA3₃ at 100% RH increased the osmotic potential in internodes of excised stem segments, while GA₃ at 20% RH maintained the osmotic potential at a low level. In internodes of stem segments that had been treated with GA₃ at 20% RH, the activity of invertase and the level of soluble sugars were almost 2- and 1.5-fold higher, respectively, than those in internodes that had been treated with GA₃ at 100% RH. These results indicate that one of the possible mechanisms by which GA₃ promotes elongation of internodes at low RH involves the osmoregulation that is achieved by promotion of the synthesis of invertase.     

Proteome analysis of cultivar-specific deregulations of Oryza sativa indica and O. sativa japonica cellular suspensions undergoing rice yellow mottle virus infection

We have used two-dimensional gel electrophoresis with mass spectrometry analysis to study the temporal patterns of protein expression during RYMV (Rice yellow mottle virus) infection in rice cells of two cultivars: IR64, Oryza sativa indica, susceptible, and Azucena, O. sativa japonica, partially resistant to RYMV. Proteomic analysis of nonstressed and RYMV inoculated cells showed statistically significant changes in the relative levels of 40 IR64 proteins and 24 Azucena proteins. Protein identification using mass spectrometry was attempted for all the differentially regulated proteins. This global analysis detected 32 hypothetical "new" proteins. Nineteen differentially regulated proteins were identified for IR64 cultivar, while 13 were identified for Azucena cultivar, including proteins in three functional categories: metabolism, stress-related proteins, and translation. These data revealed that a number of proteins regulated by abiotic stress response pathway were activated by RYMV in both cultivars (such as salt-induced protein, heat shock proteins (HSPs), superoxide dismutase (SOD), and others have functions consistent with the susceptibility or partially resistance trait (such as dehydrin, proteins involved in glycolysis pathway).     

不同生育阶段夜温升高对双季水稻物质生产与养分吸收的影响

利用2间玻璃室内夜间不同的温度条件,研究了水稻生长期间夜温升高对双季早、晚稻物质生产和养分积累的影响.结果表明:播种-幼穗分化期夜温升高增加早稻的干物质积累,而减少晚稻的干物质积累;幼穗分化期-抽穗的夜温升高对早、晚稻的干物质积累均有一定的负作用;抽穗后的夜温升高对早稻物质生产影响较小,但降低其茎鞘物质的转运,而晚稻的干物质生产和茎鞘物质的转运均提高.在早稻幼穗分化前夜温适度升高有利于提高根系活力,促进植株养分的积累,但不利于晚稻植株养分的积累;幼穗分化-抽穗期间的夜温升高均不利于早、晚稻植株的养分积累;灌浆结实期的夜温升高会造成早稻根系早衰,不利于养分吸收,但有利于保持晚稻根系较高活力,促进养分吸收.试验证明,不同生育阶段的夜温升高对双季水稻不同生育阶段的干物质生产和养分吸收的影响是不同的.     

灌浆期气温与源库强度对稻米品质的影响及其生理分析

利用自然条件下的早、晚季种植作为温度处理,选择米质低、中、优等级的6个水稻品种（组合）作为供试材料,研究了早、晚季种植下的稻米品质、淀粉分支酶活性变化,以及温度处理间的差异.结果表明,在籽粒灌浆初期,高温环境下灌浆充实的籽粒,其稻米的垩白增加、透明度变差、整精米率下降,对出糙率及精米率没有明显影响.与早季种植的稻米相比,晚季种植稻米的胶稠度、整精米率、透明度增加.早、晚季种植对稻米直链淀粉含量、蛋白质含量等没有显著影响.剪叶限源处理显著降低稻米质量,疏粒减库处理显著提高稻米品质.     

Oxygen evolution rate of rice cultivars

Under natural conditions we found a significant variation in oxygen evolution rate (OER) in flag leaves of different rice genotypes during the grain filling stage. Cv. Roxinho showed the highest OER [42 μmol(O₂) m⁻² s⁻¹], followed by BRS Taim, BRS Pelota, BRS Bojuru, IR58025B, BRS 6 Chui, and BR-IRGA 409, with 37.0, 34.0, 33.0, 31.8, 29.0, 28.0, and 27.6 μmol(O₂) m⁻² s⁻¹, respectively. The lack of fertility in the male-sterile rice line IR58025A prolonged the photosynthetic capacity by at least 15 d when compared to the normal fertility found in the IR58025B line. No difference was observed in OER among first (flag) and second leaves in both IR58025A and IR58025B rice lines.     

不同化感潜力水稻(Oryza sativa L.)苗期的氮素养分效率及相关基因的表达

为了阐明养分水平引起水稻(Oryza sativa L.)化感抑草潜力变化的生理生态机制,研究了不同N素营养处理下,不同化感潜力水稻苗期对N素营养逆境的响应特性及N素养分效率的差异,并运用实时荧光定量RT-PCR技术(FQ-PCR)检测与N素代谢和次生代谢关键酶的基因表达.结果表明:弱化感水稻品种Lemont对N素营养胁迫较敏感,强化感水稻品种PI312777对资源波动的适应性较强,N素养分效率较高.FQ-PCR分析结果显示,在低N条件下Lemont中的亚硝酸还原酶基因(nir),谷氨酰胺合成酶基因(gs)相对表达量均有不同幅度的下调, PI312777分别下调了1.2倍和1.4倍,而Lemont分别下调了3.0倍和1.8倍, Lemont下调的幅度分别是PI312777的2.5倍和1.3倍,但对于苯丙氨酸解氨酶基因(pal)与3-羟基-3甲基戊二酰辅酶A还原酶基因(hmgr)而言, PI312777叶组织中的pal和hmgr均上调表达,与对照相比上调了6.0倍和1.6倍,而Lemont中对应的基因均下调表达,分别下调了1.3倍和6.8倍,佐证了上述差异的分子生态学特性.     

Genetic analysis for drought resistance of rice at reproductive stage in field with different types of soil

Drought resistance of rice is a complex trait and is mainly determined by mechanisms of drought avoidance and drought tolerance. The present study was conducted to characterize the genetic basis of drought resistance at reproductive stage in field by analyzing the QTLs for drought response index (DRI, normalized by potential yield and flowering time), relative yield, relative spikelet fertility, and four traits of plant water status and their relationships with root traits using a recombinant inbred population derived from a cross between an indica rice and upland rice. A total of 39 QTLs for these traits were detected with individual QTL explained 5.1–32.1% of phenotypic variation. Only two QTLs for plant water status were commonly detected in two environments, suggesting different mechanisms might exist in two types of soil conditions. DRI has no correlation with potential yield and flowering time under control, suggesting that it can be used as a good drought resistance index in field conditions. The co-location of QTLs for canopy temperature and delaying in flowering time suggested a usefulness of these two traits as indexes in drought resistance screening. Correlation and QTL congruence between root traits and putative drought tolerance traits revealed that drought avoidance (via thick and deep root traits) was the main genetic basis of drought resistance in sandy soil condition, while drought tolerance may play more role in the genetic basis of drought resistance in paddy soil condition. Therefore, both drought mechanisms and soil textures must be considered in the improvement of drought resistance at reproductive stage in rice.     

水稻苗期磷高效基因型筛选研究

采用难溶性磷酸盐Ca3 (PO4) 2 为唯一磷源 ,在pH值为 5 .5条件下产生相对高浓度低磷胁迫及以NaH2 PO4为磷源配制P浓度为 0 .5mg·L-1的相对低浓度低磷胁迫的两个水培环境 ,分别对不同基因型水稻的磷效率进行评价 .以相对分蘖干重 (RTW )、相对总生物量 (RPW )、相对分蘖数 (RTN)、相对根系干重(RRW )、相对地上部干重 (RSW )、相对叶龄 (RLA)和相对株高 (RPH)作为耐性指标进行相关分析 .结果表明 ,供试材料的磷效率存在极显著差异 ,若以能产生分蘖的相对高浓度低磷胁迫进行筛选时 ,相对分蘖干重、相对地上部干重、相对总生物量可作为较好的筛选指标 ,其中相对分蘖干重不仅与其它指标间的相关性强 ,且品种间差异和变异系数均较大 ,能准确、灵敏地反映不同基因型间的耐低磷胁迫能力 ;若采用相对低浓度的低磷胁迫对不同基因型水稻进行耐低磷种质筛选时 ,筛选指标则不同 ,最好的单一筛选指标应是相对地上部干重或相对总生物量 .     

Effects of rhizosphere oxygen concentration on root physiological characteristics and anatomical structure at the tillering stage of rice

Oxygen is essential for all aerobic organisms. Higher plants need oxygen to sustain metabolism and growth. After experiencing anaerobic stress for a period of time, most plant tissues will be damaged. This study examined the physiological characteristics and anatomical structures in the root tips of rice seedlings (cultivars Xiushui09 and Chunyou84) in response to different rhizosphere oxygen environments. The results showed that moderate oxygen (MO: 2.5–3.5 mg L⁻¹) increased the dry weight accumulation and formation of rice roots (including length, surface area, number of tips) in both genotypes. Compared to under normal conditions (NC), the magnitudes of increase in these four variables were 4.67, 66.40, 35.44 and 49.50% in Xiushui09 and 12.25, 15.59, 13.57 and 13.48% in Chunyou84, respectively. Low oxygen (LO: 0–1.0 mg L⁻¹) stress decreased the root surface area but increased root volume and average diameter. LO and high oxygen (HO: >6.8 ± 0.21 mg L⁻¹) stress each damaged the apical cells' ultrastructure, reduced the number of organelles, and increased electrical conductivity. Meanwhile, the root activity and respiration of rice seedlings decreased; the abscisic acid content increased compared to levels under NC. Under MO treatment, the cell membrane was not damaged, the root tip organelles were rich, the soluble protein content, root activity, respiration rate and gibberellic acid content increased compared to levels under NC; the magnitudes of these increases were 24.76, 36.00, 8.00 and 283.00% in Xiushui09 and 4.78, 40.00, 15.45 and 49.35% in Chunyou84, respectively. In conclusion, MO optimised rice root morphology and enhanced root physiological activity.