普通野生稻和武育粳8号剑叶光合功能衰退的比较

以武育粳 8号 (Wuyujing8)和普通野生稻 (Oryza.sativaL .f.spontaneaRoschev .)为材料 ,比较了它们剑叶光合功能衰退的进程。结果表明 ,在剑叶一生中 ,武育粳 8号剑叶的叶绿素含量和光合速率都高于普通野生稻 ,光合速率的最高值前者为 2 3 .5 μmolCO2 m 2 ·S 1,后者为 1 5 .5 μmolCO2 m 2 ·S 1。前者剑叶光合速率的高值持续期比后者长近 2 0d ,其叶源量是后者的 2 .8倍。武育粳 8号剑叶叶绿素含量最大值的SPAD值为 5 0 .1 ,而普通野生稻最大值的SPAD值为 42 .7。在可溶性蛋白质的基础上 ,核酮糖 1 ,5 二磷酸羧化酶比活性二者之间没有太大区别。内肽酶活力上升落后于光合功能的衰退。在光合功能衰退的早期 ,内肽酶的活力仅有小幅度提高 ,但在叶片衰老的末期升高幅度则较大。这说明内肽酶主要在光合功能衰退的后期即不可逆衰退期才发挥较大作用。     

Daily changes in components of xanthophyll cycle and antioxidant systems in leaves of rice at different developing stage

The daily changes in the behavior of xanthophyll cycle and antioxidant systems in flag leaves of superhigh-yield hybrid rice were investigated in relation to various developing stages. Dark-adapted Fv/Fm decreased with the increasing incident light intensity on leaf surface in the morning and then minimized at midday; Deepoxidation State showed an opposed daily pattern to Fv/Fm at different developing stage. As compared with increased deepoxidation state maximum value, the relative content of xanthophyll cycle pigments remained almost constant during development. The daily changes in activities of superoxide dismutase, ascorbate-peroxidase and glutathione reductase and the content of ascorbate and glutathione displayed a similar pattern, where they increased from 8:00 and reached maximum at midday, however, a lower daily fluctuation of superoxide dismutase activity was observed in senescent leaves. The enhanced contribution of xanthophyll cycle and Mehler-ascorbate peroxidase reaction to photoprotection in old leaves could be partially due to the altered leaf posture. In conclusion, daily changes of xanthophyll cycle and antioxidant systems in leaves of rice at various developing stages were dependent on leaf age, leaf angle and intensity of solar irridiance.     

八倍体小偃麦和普通小麦旗叶及叶鞘光合日变化比较研究

以温室大棚中栽培的普通小麦'中国春'(对照)及八倍体小偃麦'小偃7430'(染色体组为ABDE_1)、'小偃693'(染色体组为ABDF_1)为材料,采用TPS-1光合作用测定系统及FMS-2荧光仪测定了开花期旗叶和叶鞘的净光合速率、气孔导度和叶绿素荧光参数的日变化,以揭示普通小麦与八倍体小偃麦旗叶及其叶鞘的光合作用差异.结果表明:八倍体小偃麦与普通小麦'中国春'的旗叶和叶鞘光合作用均有午休现象,净光合速率于上午11:00左右出现高峰,午间下降,下午又呈现上升趋势,且'小偃693'叶片在上午时上升较快;气孔导度和荧光参数F_v/F_m、Fv/F_o、 Φ_(PS)Ⅱ、ETR的变化趋势与净光合速率相似,而NPQ的变化趋势则相反.各光合作用和叶绿素荧光参数在材料间表现为八倍体小偃麦高于普通小麦'中国春',器官间表现为旗叶高于相应叶鞘,而'小偃693'的叶鞘和'中国春'叶片的相似.研究发现,八倍体小偃麦旗叶和叶鞘的光合效率优于普通小麦'中国春';'小偃693'的光合效率因其较高的光反应活性表现得尤为突出,其叶鞘的光合能力也不容忽视.     

杂交粳稻花优14及其亲本孕穗期剑叶的基因表达谱芯片分析

本文以孕穗期的杂交粳稻花优14及其母本申9A和父本繁14的剑叶为材料,利用Affymetrix水稻基因组芯片检测了3个样品中的基因表达谱,并用生物信息学方法对差异表达基因进行了分析。结果表明：与其亲本相比,杂交粳稻花优14中共有2057个基因的表达水平出现了2倍(变化倍数≥2或≤0.5)以上的变化。通过对这些差异表达基因进行GO(Gene Ontology)功能分类,发现差异表达基因在光合系统Ⅰ、叶绿体膜和叶绿体被膜等与叶绿体相关的细胞组分中显著富集;同时差异表达基因还在叶绿素合成、叶绿素代谢和类胡萝卜素合成等生物学过程中富集。光合作用效率的改变可能和花优14杂种优势的形成相关。与已报道结果不同,本文在代谢途径分析结果中并没有发现花优14中差异表达基因在碳固定和光合作用等途径中显著的富集,但是发现差异表达基因在光合作用-天线蛋白以及淀粉和蔗糖的代谢途径中显著富集。该结果表明,在不同的杂交组合中,参与杂种优势形成的基因或者代谢途径可能是不同的。     

甜瓜幼苗叶片光合变化特性

为探讨甜瓜光响应变化特性与环境因子的关系,选择光响应曲线适宜测定的时段,以甜瓜幼苗为试材,将1 d分为3个时段:10:00-12:00、12:00-15:00和15:00-17:00,每个叶位叶片测定1 d,并采用直角双曲线修正模型拟合光响应曲线,研究不同时段下甜瓜叶片光响应曲线、光响应参数的变化趋势和不同叶位叶片光响应参数特性。结果表明:当环境中光合有效辐射增强,叶面温度(Tl)升高,空气相对湿度(RH)降低;当环境中光合有效辐射减弱,Tl降低,RH升高。10:00-12:00光响应曲线和12:00-15:00的第1-4叶光响应曲线呈双曲线,在强光下趋向饱和状况,12:00-15:00的第5叶光合速率和15:00-17:00光合速率在强光下出现明显的光抑制现象。1 d的不同时段均表现为10:00-12:00最大净光合速率(P_max)和光饱和点(LSP)最高,12:00-17:00降低;12:00-15:00光补偿点(LCP)和暗呼吸速率(R_d)较高,其它两个时段较低,10:00-17:00光补偿点量子效率(φ_c)、气孔导度(G_s)和胞间CO₂浓度(C_i)总体呈降低趋势,气孔限制值(L_s)升高。10:00-15:00相同时段测得的不同叶位叶片光响应参数,以第4-5叶光合性能较好,15:00-17:00以第3叶P_max最高,第5叶次之;10:00-17:00 G_s和C_i以第5叶较低,第1叶较高,L_s以第5叶较高,第1叶较低。RH为影响P_max的主要决策因子,测定时段、叶面饱和蒸汽压亏缺(Vpdl)和Tl为主要限制因子。10:00-12:00适宜进行光响应曲线测定,气孔限制为不同时段光合作用不同的主要因素,非气孔限制为影响不同叶位叶片光合作用的主要因素。     

Phosphorus remobilization from rice flag leaves during grain filling: an RNA‐seq study

The physiology and molecular regulation of phosphorus (P) remobilization from vegetative tissues to grains during grain filling is poorly understood, despite the pivotal role it plays in the global P cycle. To test the hypothesis that a subset of genes involved in the P starvation response are involved in remobilization of P from flag leaves to developing grains, we conducted an RNA‐seq analysis of rice flag leaves during the preremobilization phase (6 DAA) and when the leaves were acting as a P source (15 DAA). Several genes that respond to phosphate starvation, including three purple acid phosphatases (OsPAP3, OsPAP9b and OsPAP10a), were significantly up‐regulated at 15 DAA, consistent with a role in remobilization of P from flag leaves during grain filling. A number of genes that have not been implicated in the phosphate starvation response, OsPAP26, SPX‐MFS1 (a putative P transporter) and SPX‐MFS2, also showed expression profiles consistent with involvement in P remobilization from senescing flag leaves. Metabolic pathway analysis using the KEGG system suggested plastid membrane lipid synthesis is a critical process during the P remobilization phase. In particular, the up‐regulation of OsPLDz2 and OsSQD2 at 15 DAA suggested phospholipids were being degraded and replaced by other lipids to enable continued cellular function while liberating P for export to developing grains. Three genes associated with RNA degradation that have not previously been implicated in the P starvation response also showed expression profiles consistent with a role in P mobilization from senescing flag leaves.     

Location Distribution Characteristics in Leaf Lateral Asymmetry of Hybrid Indica Rice

Rice leaves show lateral asymmetry. Differences in width, thickness, chlorophyll meter readings, nitrogen content, density, and yield on each asymmetrical have been reported. However, limited information is available on the distribution characteristics of the smooth side (SS) and rough side (RS) of rice leaves. The SS of rice leaves can be divided into two types according to its location in leaf: one is the smooth side appearing on the left (SSAL) of the leaf, while the smooth side of the other type appears on the right (SSAR). Through the investigation of four rice varieties, we identified that the proportion of SSAL or SSAR of flag leaves on main stems or tillers was close to 0.50 in the rice population. On the same tiller stem, SSAL and SSAR present alternately, and the SS always stretches ahead of the RS in the curled state. Among the tiller flag leaves of a single rice plant, the proportion of tiller flag leaves with SSAL or SSAR to the total number of tillers is a discrete random variable. Frequency distribution analysis of these proportions showed that the percent of frequency of some class limits was close to each other, and the ratios of percent of frequency of SSAL to SSAR were close to 1:1. To our knowledge, this is a novel finding in rice canopy morphology. According to this study, we can divide rice population into two groups in four hybrid rice varieties.     

Influence of ozone on ribonuclease activity in wheat (Triticum aestivum) leaves

Ribonucleases (RNases) degrade RNA and exert a major influence on gene expression during development and in response to biotic and abiotic stresses. RNase activity typically increases in response to pathogen attack, wounding and phosphate (P(i)) deficiency. Activity also increases during senescence and other programmed cell death processes. The air pollutant ozone (O(3)) often induces injury and accelerated senescence in many plants, but the biochemical mechanisms involved in these responses remain unclear. The objective of this study was to determine whether RNase activity and isozyme expression was stimulated in wheat (Triticum aestivum L.) flag leaves following treatment with O(3). Plants were treated in open-top chambers with charcoal-filtered air (27 nmol O(3) mol(-1)) (control) or non-filtered air plus O(3) (90 nmol O(3) mol(-1)) (O(3)) from seedling to reproductive stage. After exposure for 56 days, RNase activity was 2.1 times higher in flag leaf tissues from an O(3)-sensitive cultivar in the O(3) treatment compared with the control, which generally coincided with foliar injury and lower soluble protein concentration, but not soluble leaf [P(i)]. Soluble [P(i)] in leaf tissue extracts from the O(3) and control treatments was not significantly different. RNase activity gels indicated the presence of three major RNases and two nucleases, and their expression was enhanced by the O(3) treatment. Isozymes stimulated in the O(3) treatment were also stimulated in naturally senescent flag leaf tissues from plants in the control. However, soluble [P(i)] in extracts from naturally senescent flag leaves was 50% lower than that found in green flag leaves in the control treatment. Thus, senescence-like pathological responses induced by O(3) were accompanied by increased RNase and nuclease activities that also were observed in naturally senescent leaves. However, [P(i)] in the leaf tissue samples suggested that O(3)-induced injury and accelerated senescence was atypical of normal senescence processes in that P(i) export was not observed in O(3)-treated plants.     

生物有机肥对盐碱地水稻叶片的影响转录组分析

改良修复盐碱地对保障粮食安全和守护耕地红线具有重要意义,种植水稻配施生物有机肥是修复改良盐碱地的一项有效措施。基于生物有机肥肥料效应,测定水稻灌浆期农艺性状,开展叶片转录组测序,通过基因本体(GO)和京都基因与基因组百科全书(KEGG)数据库分析差异基因的生物学功能和代谢通路,以期揭示生物有机肥对盐碱地水稻的潜在促生机制。试验共设置4个处理,生物有机肥+化肥(T1)、生物有机肥灭活+化肥(T2)、化肥(T3)和空白对照(T4),结果表明,施用生物有机肥能够显著提高水稻叶面积和叶绿素、植株分蘖数和干物质量(P<0.05);T2vsT1、T3vsT1、T4vsT1、T4vsT3差异基因数量分别为6593、4796、6976和1866条,生物有机肥配施化肥引起差异基因表达数量最高,其次为灭活生物有机肥,单施化肥最小;GO分析显示,生物有机肥主要影响水稻叶片肽和酰胺的生物合成与代谢、翻译过程、细胞器及细胞器膜等,化肥对水稻叶片生物学过程影响的差异基因无显著富集(P>0.05);KEGG分析表明,施用生物有机肥差异显著基因主要富集在核糖体和能量代谢相关途径,核糖体相关基因差异表达较多...     

Starch-branching enzyme IIa is required for proper diurnal cycling of starch in leaves of maize

Starch-branching enzyme (SBE), a glucosyl transferase, is required for the highly regular pattern of α-1,6 bonds in the amylopectin component of starch. In the absence of SBEIIa, as shown previously in the sbe2a mutant of maize (Zea mays), leaf starch has drastically reduced branching and the leaves exhibit a severe senescence-like phenotype. Detailed characterization of the maize sbe2a mutant revealed that SBEIIa is the primary active branching enzyme in the leaf and that in its absence plant growth is affected. Both seedling and mature sbe2a mutant leaves do not properly degrade starch during the night, resulting in hyperaccumulation. In mature sbe2a leaves, starch hyperaccumulation is greatest in visibly senescing regions but also observed in green tissue and is correlated to a drastic reduction in photosynthesis within the leaf. Starch granules from sbe2a leaves observed via scanning electron microscopy and transmission electron microscopy analyses are larger, irregular, and amorphous as compared with the highly regular, discoid starch granules observed in wild-type leaves. This appears to trigger premature senescence, as shown by an increased expression of genes encoding proteins known to be involved in senescence and programmed cell death processes. Together, these results indicate that SBEIIa is required for the proper diurnal cycling of transitory starch within the leaf and suggest that SBEIIa is necessary in producing an amylopectin structure amenable to degradation by starch metabolism enzymes.     

蕾后期和花前期切花菊品种'神马'不同部位叶片光合作用和叶绿素荧光特性的比较

对蕾后期和花前期切花菊(Chrysanthemum morifolium Ramat.)品种'神马'('Jinba')不同部位叶片光合作用参数日变化、叶绿素荧光参数、光响应曲线及参数进行了研究.结果表明:蕾后期和花前期品种'神马'叶片蒸腾速率(Tr)、气孔导度(Gs)和净光合速率(Pn)的日变化均为单峰曲线,峰值出现在10:00或12:00;胞间CO2浓度(Ci)的日变化则先降低后升高,谷值出现在12:00.蕾后期和花前期品种'神马'叶片Tr、Ci和Gs值的平均值总体上随叶片位置降低而逐渐升高;蕾后期不同部位叶片Pn值的平均值差异较小,花前期叶片Pn值的平均值则随叶片位置降低而逐渐降低.随着叶片位置降低,蕾后期和花前期品种'神马'叶片的初始荧光(Fo)、最大荧光(Fm)、可变荧光(Fv)、表观量子效率(AQE)和最大净光合速率(Pmax)以及蕾后期的暗呼吸速率(Rd)均逐渐降低,而花前期的Rd值以及蕾后期和花前期的光补偿点(LCP)均逐渐升高.随着光合有效辐射(PAR)升高,蕾后期不同部位叶片以及花前期中部叶和下部叶的Pn值呈先急剧升高后趋于平稳的变化趋势,而花前期上部叶的Pn值则呈先急剧升高后逐渐下降的变化趋势.研究结果显示:在切花菊设施栽培过程中适当补充光照可提高切花菊品质.     

The anti-photooxidation of anthocyanins-rich leaves of a purple rice cultivar

In the leaf of rice (Oryza sativa L.) cultivar Yunnan purple rice,the anthocyanins with an obvious absorption peak at 530nm were distributed in the cells of upper and lower epidermis,bulliform tissue and bristle. The maximal photosynthetic oxygen evolution rate and chlorophyll content in flag leaves were 28% and 23%,respectively,more than the common green leaf rice cultivar Chijiaoru-anzhan. Higher chlorophyll content is probably one of the physiological adaptations for enhancing light harvesting capacity of the antenna in photosystems in this cyanic leaves species. Upon the photooxidation of leaf segments mediated by methyl viologen in weak light for 3 days,the distinct bleaching of anthocyanins in purple rice was associated with the reduction of scavenging ability to DPPH· free radical ability and the increase in membrane leakage rate. But almost no changes in contents of flavonoids and total phenolics were observed. Chlorophyll fluorescence parameters Fv/Fo,qP and φPSⅡ decreased with the increase in NPQ and DES of xanthophylls cycle after photooxidation treatment. Green rice leaves showed more decrease in DPPH· scavenging rate and more increase in cell membrane leakage rate but showed a trace of anthocyanins during photooxidation. It is sug-gested that anthocyanin may be a beneficial and primary antioxidant in sun cyanic rice leaves against oxidative stress induced by environmental adversity. And photooxidation could induce different changing patterns of anthocyanins between the tested purple and green rice leaves.