小麦进化过程中叶片气孔和光合特征演变趋势

根据小麦属内种间的进化关系选取21种小麦品种为实验材料,研究了小麦进化过程中气孔特征和光合特征的演变趋势。结果表明,无论是A,B,D染色体组还是A,G染色体组,气孔长度、宽度、周长、面积均随倍性水平的升高而呈增大趋势,而气孔指数无显著变化;A,B,D染色体组气孔密度随倍性升高呈减少趋势。二倍体小麦的Pn值最高,六倍体小麦的Fv/Fm值较高,二倍体小麦叶片叶绿素含量显著高于四倍体和六倍体小麦。不同倍性小麦的净光合速率与气孔导度间均存在极显著相关关系,表明气孔传导力是小麦光合能力的主要限制因素之一。气孔导度与单一气孔特征之间无显著相关关系。A,B,D染色体组不同倍性小麦叶片气孔密度差异显著,其大小顺序为二倍体〉四倍体〉六倍体;A,B,D染色体组不同倍体小麦叶片的气孔长度、宽度、周长、面积差异显著,顺序均为六倍体〉四倍体〉二倍体,气孔密度降低可能是A,B,D染色体组六倍体小麦光合能力降低的原因。随着倍性的升高,小麦的抵抗光抑制能力越强,因此光化学能转换效率可能不是小麦进化过程中光合能力变化的原因。A,B,D染色体组中二倍体的叶绿素含量显著大于四倍体和六倍体,而A,G染色体组中倍体间叶绿素含量差异不显著,说明叶绿素的降低可能是A,B,D染色体组六倍体光合能力降低的原因之一。     

Differences in stomatal and photosynthetic characteristics of five diploidy wheat species

Five diploidy wheat species were chosen as research materials to determine the differences in stomatal and photosynthetic characteristics. The results of the study showed that species with S genomes (Ae. Sect. Sitopsis) had the largest values in stomatal length, girth and area, and the lowest values in stomatal width, density and index. On the contrary, the species with D genomes (Ae. Tauschii) had the highest values in stomatal width, density and index, and the lowest values in stomatal length, girth and area. The net photosynthetic rate (Pn) and stomatal conductance (Gs) were higher in species with D genomes (Ae. Tauschii) and lower in species with S genomes (Ae. Sect. Sitopsis), respectively. The net photosynthetic rate showed significant correlation with stomatal conductivity, and the changes in intercellular CO₂ content showed the opposite trend to the changes in stomatal limitation, indicating that the stomatal conductivity is the main factor limiting the photosynthetic rate. T. urartu with higher net photosynthetic ability showed higher values in stomatal conductivity and stomatal limitation, and lower values in intercellular CO₂ content. However, T. boeoticum showed the opposite trend. T. urartu had higher values of chlorophyll content in flag leaf area, while T. boeoticum had lower values, indicating that there might be higher chlorophyll content.     

二倍体小麦种间气孔与光合特征差异

选取5个二倍体小麦种为实验材料,利用数码图像显微镜处理系统、气体交换参数测定系统和叶绿素荧光动力学参数测定系统,研究了二倍体小麦种间气孔特征与光合特性的差异.结果表明,二倍体小麦种间气孔和光合特征存在较大的差异:其中S基因型(Ae.Sect.Sitopsis)的气孔长度、周长和面积最大,而其宽度、密度和气孔指数却是最小的;D基因型(Ae.Tauschii)的气孔宽度、密度和气孔指数最大,而其长度、周长和面积却是最小的;D基因型(Ae.Tauschii)的净光合速率最大,而S基因型(Ae.Sect.Sitopsis)的净光合速率最小.气孔周长与气孔面积呈显著正相关关系,而气孔密度与气孔面积呈显著负相关关系.二倍体小麦的净光合速率与气孔导度呈显著正相关关系,同时气孔限制值的变化趋势与细胞间隙CO2浓度的变化趋势相反,说明二倍体小麦的光合能力主要受气孔限制.在几个种中,乌拉尔图小麦(T.urartu)具有较高的净光合速率和气孔导度,同时细胞间隙CO2浓度最低,气孔限制值最大,在光合能力和耐光抑制方面有较明显的优势;而野生一粒小麦(T.boeoticum)则在光合能力和耐光抑制方面不存在优势.同时,乌拉尔图小麦(T.urartu)的叶绿素含量最高,而野生一粒小麦(T.boeoticum)最低,叶绿素含量可能也是造成二倍体种间光合能力差异的原因之一.     

Changes in Root Hydraulic Conductivity During Wheat Evolution

A better understanding of the mechanisms of water uptake by plant roots should be vital for improving drought resistance and water use efficiency (WUE). In the present study, we have demonstrated correlations between root system hydraulic conductivity and root characteristics during evolution using six wheat evolution genotypes (solution culture) with different ploidy chromosome sets (Triticum boeoticum Bioss., T. monococcum L.: 2n=2x=14;T. dicoccides Koern., T. dicoccon (Schrank) Schuebl.:2n=4x=28;T. vulgare Vill., T. aestivum L. cv. Xiaoyan No. 6:2n=6x=42). The experimental results showed that significant correlations were found between root system hydraulic conductivity and root characteristics of the materials with the increase in ploidy chromosomes (2x→6x) during wheat evolution. Hydraulic conductivity of the wheat root system at the whole-plant level was increased with chromosome ploidy during evolution, which was positively correlated with hydraulic conductivity of single roots, whole plant biomass,root average diameter, and root growth (length, area), whereas the root/shoot ratio had an inverse correlation with the hydraulic conductivity of root system with increasing chromosome ploidy during wheat evolution. Therefore, it is concluded that that the water uptake ability of wheat roots was strengthened from wild to modern cultivated species during evolution, which will provide scientific evidence for genetic breeding to improve the WUE of wheat by genetic engineering.     

Changes in Root Hydraulic Conductivity During Wheat Evolution

A better understanding of the mechanisms of water uptake by plant roots should be vital for improving drought resistance and water use efficiency (WUE). In the present study, we have demonstrated correlations between root system hydraulic conductivity and root characteristics during evolution using six wheat evolution genotypes (solution culture) with different ploidy chromosome sets (Triticum boeoticum Bioss., T. monococcum L.: 2n = 2x = 14; T. dicoccides Koern., T. dicoccon (Schrank) Schuebl.: 2n = 4x = 28;T. vulgare Vill., T. aestivum L. cv. Xiaoyan No. 6: 2n = 6x = 42). The experimental results showed that significant correlations were found between root system hydraulic conductivity and root characteristics of the materials with the increase in ploidy chromosomes (2x→6x) during wheat evolution. Hydraulic conductivity of the wheat root system at the whole-plant level was increased with chromosome ploidy during evolution, which was positively correlated with hydraulic conductivity of single roots, whole plant biomass,root average diameter, and root growth (length, area), whereas the root/shoot ratio had an inverse correlation with the hydraulic conductivity of root system with increasing chromosome ploidy during wheat evolution. Therefore, it is concluded that that the water uptake ability of wheat roots was strengthened from wild to modern cultivated species during evolution, which will provide scientific evidence for genetic breeding to improve the WUE of wheat by genetic engineering.     

土壤水分对冬小麦生育后期叶片气体交换及叶绿素荧光参数的影响

通过防雨棚小区栽培,控制土壤供水系数(Kw)分别为0.8、0.6、0.4、0.2,以自然状况下的小区为对照(CK),研究土壤水分条件对冬小麦生育后期叶片气体交换及叶绿素荧光参数的影响。结果表明:Kw为0.6处理的冬小麦叶片叶绿素含量与0.8处理接近,且显著高于其他处理(P<0.05);Kw为0.6处理对冬小麦叶片的气孔导度和蒸腾速率有轻度抑制,但其光合速率却高于0.8处理,而Kw为0.2处理的光合速率、气孔导度及蒸腾速率均为最低;气孔限制值在Kw为0.4处理下最高,其次为0.2处理,0.8处理下最低;冬小麦叶片的表观量子效率在Kw为0.4处理下最高,光补偿点总体上随着土壤水分含量的降低呈下降趋势,而光饱和点及最大光合速率则以Kw为0.6处理最高,其次为0.8处理,0.2处理最低;冬小麦叶片的天线转化效率Fv’/Fm’、电子传递速率ETR、实际量子效率ФPSII及光化学猝灭qP均以Kw为0.6处理最高,其次为0.8处理,0.2处理下最低;在Kw为0.2处理下,冬小麦光合作用主要受非气孔因素限制,而在0.4处理下,则主要受气孔因素限制。     

5种松属树种光合功能及叶绿素快相荧光动力学特征比较

以松属5种代表树种日本五针松、华山松、白皮松、油松和赤松为研究对象,比较了它们针叶的形态特征、光合速率和叶绿素快相荧光动力学方面的异同.结果表明:5种松树的针叶形态特征存在显著差异,油松的针叶长度和密度最大;白皮松的叶绿素含量最高;但赤松的光合速率最大,日本五针松的光合速率最小.5种松树针叶的光合速率与气孔导度呈正相关.5种松树的叶绿素快速荧光诱导动力学曲线的差异主要表现在J相和I相.尽管5种松树光系统Ⅱ(PSⅡ)最大光化学效率(Fv/Fm)、潜在光化学活性(Fv/Fo)以及到达最大荧光所需的时间(Tfm)差异不显著,但日本五针松的反应中心关闭净速率dV/dto和dVG/dto以及J相和I相的相对可变荧光强度(Vj和Vi)显著大于其他4种松树,能量分配比率Ψo、φEo、φRo显著低于其他4种松树.这可能与日本五针松的质体醌库大小(Sm)、质体醌库还原速率(Sm/Tfm)和质体醌A(QA)的周转次数(N)最小有关.日本五针松的性能指数PI(ABS/CSo/CSm)和光合驱动力(DF)均显著低于其他4种松树,而赤松PI和DF最高.其中PI(Cso)和PI(CSm)与5种松树的净光合速率呈显著正相关,可以作为评价松树光合能力的荧光指标.     

盐胁迫对不同种源麻栎叶片光合特征的影响

采用5 个不同盐浓度处理,研究了盐胁迫对山东费县、安徽滁州和四川万源3个种源地麻栎叶片光合特征的影响.结果表明：随着盐浓度的增加,3个种源的麻栎叶片叶绿素a、叶绿素b、净光合速率（P_n）均呈下降趋势,其中叶绿素a在山东种源中降幅最大,下降了21.5%～36.1%,四川种源降幅最小,在3.5%～19.8%之间.所有种源对照组的P_n均成“单峰”曲线,未出现“午休”现象;高盐浓度处理下则有明显的午休现象,经通径分析,P_n主要受饱和水汽压差和叶温的影响,气孔导度、胞间CO₂浓度和光强是次要因子.不同种源对照处理的麻栎叶片光合特征受原种源地环境因子的影响较大.麻栎的耐盐胁迫能力大小为：四川万源种源>安徽滁州种源>山东费县种源.     

Differential adaptation of two varieties of common bean to abiotic stress: II. Acclimation of photosynthesis

The photosynthetic characteristics of two contrasting varieties of common bean (Phaseolus vulgaris) have been determined. These varieties, Arroz and Orfeo, differ in their productivity under stress conditions, resistance to drought stress, and have distinctly different stomatal behaviour. When grown under conditions of high irradiance and high temperature, both varieties displayed evidence of photosynthetic acclimation at the chloroplast level-there was an increase in chlorophyll a/b ratio, a decreased content of Lhcb proteins, and an increased xanthophyll cycle pool size. Both varieties also showed reduced chlorophyll content on a leaf area basis and a decrease in leaf area. Both varieties showed an increase in leaf thickness but only Arroz showed the characteristic elongated palisade cells in the high light-grown plants; Orfeo instead had a larger number of smaller, rounded cells. Differences were found in stomatal development: whereas Arroz showed very little change in stomatal density, Orfeo exhibited a large increase, particularly on the upper leaf surface. It is suggested that these differences in leaf cell structure and stomatal density give rise to altered rates of photosynthesis and stomatal conductance. Whereas, Arroz had the same photosynthetic rate in plants grown at both low and high irradiance, Orfeo showed a higher photosynthetic capacity at high irradiance. It is suggested that the higher yield of Orfeo compared with Arroz under stress conditions can be explained, in part, by these cellular differences.     

Assessment of genetic diversity among Syrian durum (<Emphasis Type="Italic">Triticum</Emphasis> ssp. <Emphasis Type="Italic">durum</Emphasis>) and bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) using SSR markers

Genetic diversity among 49 wheat varieties (37 durum and 12 bread wheat) was assayed using 32 microsatellites representing 34 loci covering almost the whole wheat genome. The polymorphic information content (PIC) across the tested loci ranged from 0 to 0.88 with average values of 0.57 and 0.65 for durum and bread wheat respectively. B-genome had the highest mean number of alleles (10.91) followed by A genome (8.3) whereas D genome had the lowest number (4.73). The correlation between PIC and allele number was significant in all genome groups accounting for 0.87, 074 and 0.84 for A, B and D genomes respectively, and over all genomes, the correlation was higher in tetraploid (0.8) than in hexaploid wheat varieties (0.5). The cluster analysis discriminated all varieties and clearly divided the two ploidy levels into two separate clusters that reflect the differences in genetic diversity within each cluster. This study demonstrates that microsatellites markers have unique advantages compared to other molecular and biochemical fingerprinting techniques in revealing the genetic diversity in Syrian wheat varieties that is crucial for wheat improvement.     

The role of calcium in improving photosynthesis and related physiological and biochemical attributes of spring wheat subjected to simulated acid rain

The response of photosynthesis parameters, catalase, superoxide dismutase and peroxidase activity, malondialdehyde, proline, chlorophyll, yield and yield components to foliar application of calcium and simulated acid rain in wheat were investigated. Foliar treatment of calcium led to significant increases in the photosynthesis rate, transpiration rate, stomatal conductance, proline, chlorophyll, yield and yield components in plants subjected to acid rain. Antioxidant enzyme activity and lipid peroxidation in the wheat leaves decreased because of calcium foliar application. Calcium hindered degradation of the rubisco subunits under acid rain treatment compared with water-treated plants. Results suggest that acid rain induces the production of free radicals resulting in lipid peroxidation of the cell membrane so that significant increase in antioxidant enzyme activity was observed. In addition, photosynthetic parameters i.e. photosynthesis rate, transpiration rate and stomatal conductance were drastically suppressed by acid rain. The cellular damage caused by free radicals might be reduced or prevented by a protective metabolism including antioxidative enzymes and calcium. We report that foliar application of calcium before acid rain may ameliorate the adverse effects of acid rain in wheat plants.     

坡地和沼泽地野牡丹(Melastoma candidum)叶片的解剖特征与气孔气体交换特性

对在坡地和沼泽地生长的野牡丹叶的解剖特征与气孔气体交换特性的研究表明：两者在形态结构方面存在着一定的差异,坡地野牡丹叶较窄,上表皮细胞小而排列紧密,气孔密度较大,上表皮厚,沼泽地野牡丹整个叶片和海绵组织比较厚,最大导管直径和栅栏细胞长度／宽度比值大,但栅栏组织厚／海绵组织厚比值较小。坡地野牡丹与沼泽地野牡丹的叶绿素a、叶绿素b的含量和类胡萝卜素的含量以及叶绿素a,b比值的差异都很小。沼泽地野牡丹净光合速率、蒸腾速率及气孔导度较高,常用的水分利用效率(Pn／Tr)接近,沼泽地野牡丹的内在水分利用效率(Pn／Gs)略高于坡地,但差异不显著。综合分析其生境条件,土壤与野牡丹叶片解剖结构和生理生态特性相关性密切。但实验结果不足以确定两种生境下生长的野牡丹为不同的生态型。     

Assessment of genetic diversity among Syrian durum (Triticum turgidum ssp. durum) and bread wheat (Triticum aestivum L.) using SSR markers

Genetic diversity among 49 wheat varieties (37 durum and 12 bread wheat) was assayed using 32 microsatellites representing 34 loci covering almost the whole wheat genome. The polymorphic information content (PIC) across the tested loci ranged from 0 to 0.88 with average values of 0.57 and 0.65 for durum and bread wheat respectively. B genome had the highest mean number of alleles (10.91) followed by A genome (8.3) whereas D genome had the lowest number (4.73). The correlation between PIC and allele number was significant in all genome groups accounting for 0.87, 074 and 0.84 for A, B and D genomes respectively, and over all genomes, the correlation was higher in tetraploid (0.8) than in hexaploid wheat varieties (0.5). The cluster analysis discriminated all varieties and clearly divided the two ploidy levels into two separate clusters that reflect the differences in genetic diversity within each cluster. This study demonstrates that microsatellites markers have unique advantages compared to other molecular and biochemical fingerprinting techniques in revealing the genetic diversity in Syrian wheat varieties that is crucial for wheat improvement.     

FACE条件下大气O3浓度增高对小麦剑叶光合色素含量的影响

应用FACE研究平台,采用烟农19、扬麦16、嘉兴002、扬麦15和扬辐麦2号等5个小麦品种,以O3自然浓度为对照,研究了大气O3浓度增高50％对不同小麦品种剑叶光合色素含量的影响.结果表明:开放式大气O3浓度增高条件下,小麦剑叶叶绿素a(Chl a)、叶绿素b(Chl b)、叶绿素总量Chl(a+b)和类胡萝卜素含量在孕穗期和开花期与对照差异不显著,而花后各时期均不同程度的降低,其中,Chl a、Chl b和Chl(a+b)含量下降达显著水平,说明大气O3浓度增高对叶绿素合成影响较小,但加速了其衰降过程.不同品种小麦剑叶光合色素含量对大气O3浓度增高的反应存在基因型差异,扬麦15和嘉兴002对大气O3浓度增高的敏感性弱于扬麦16、扬辐麦2号和烟农19.在籽粒灌浆盛期(花后21 d左右),剑叶Chl a、Chl b和Chl(a+b)含量与千粒重呈显著正相关.     

Ploidy effects on anatomy and gas exchange of tall fescue leaves

A growth chamber study was designed to interpret differences in CO₂ exchange rate (CER) and leaf diffusive resistance among 4X, 6X, 8X, and 10X ploidy levels of tall fescue (Festuca arundinacea, Schreb). Mesophyll cell size, stomatal density, number of major and minor veins, and bundle cap size of leaf blades were evaluated. Diffusive resistance tended to decrease and CER to increase with increasing ploidy level. Mean stomatal density decreased from 43.6 per square millimeter to 30.6 per square millimeter as ploidy level increased from 4X to 8X. The 10X ploidy level exhibited the highest stomatal density, 47.2 per square millimeter. Major veins decreased from a mean of 14.2 to 10.2, and minor veins increased from a mean of 4.2 to 6.6, per leaf blade as ploidy increased from 4X to 10X. Total number of veins decreased significantly from a mean of 18.4 to 15.7 as ploidy increased from 4X to 8X.     

FACE条件下大气O3浓度增高对小麦剑叶光合色素含量的影响

应用FACE研究平台,采用烟农19、扬麦16、嘉兴002、扬麦15和扬辐麦2号等5个小麦品种,以O₃自然浓度为对照,研究了大气O₃浓度增高50%对不同小麦品种剑叶光合色素含量的影响.结果表明：开放式大气O₃浓度增高条件下,小麦剑叶叶绿素a (Chl a)、叶绿素b (Chl b)、叶绿素总量Chl(a+b)和类胡萝卜素含量在孕穗期和开花期与对照差异不显著,而花后各时期均不同程度的降低,其中,Chl a、Chl b和Chl(a+b)含量下降达显著水平,说明大气O₃浓度增高对叶绿素合成影响较小,但加速了其衰降过程.不同品种小麦剑叶光合色素含量对大气O₃浓度增高的反应存在基因型差异,扬麦15和嘉兴002对大气O₃浓度增高的敏感性弱于扬麦16、扬辐麦2号和烟农19.在籽粒灌浆盛期(花后21 d左右),剑叶Chl a、Chl b和Chl(a+b)含量与千粒重呈显著正相关.     

不同年代推出的冬小麦品种叶片气体交换日变化的差异

选择 6 0年来北京地区广泛种植的 3个冬小麦 (TriticumaestivumL .)品种 ,在相同的环境条件下种植。为了研究它们的产量与单位叶面积的净光合速率 (Pn)的关系 ,测定了不同生育期Pn、蒸腾速率 (Tr)的日变化 ,并用Pn/Tr计算叶片瞬时的水分利用率 (WUE)。结果表明 :单位叶面积净光合速率与产量之间的关系随生育期不同而变化。在拔节期高产品种“京冬 8号”(九十年代推出 )的光合速率和蒸腾速率在一天中总是最高 ,一天中差异最大时 ,分别比低产品种“燕大 1817”(四十年代推出 )高 77%和 6 9%。而其水分利用率却小于低产品种。这种差异随小麦的生长发育而变化 ,一般上午 10 :0 0前“京冬 8号”的光合速率较高 ,而 10 :0 0后“燕大 1817”的光合速率较高。到腊熟期 ,低产品种“燕大 1817”的光合速率在一天中始终最高。蒸腾速率的变化规律与光合速率相似 ,然而“燕大1817”叶片的水分利用率一般最高。与现代推出的品种不同 ,老品种“燕大 1817”叶片的光合作用午休现象不明显 ,说明它可能具有一定的抗光氧化性。我们认为 ,在品种改良的过程中 ,叶片光合作用的潜力可能有所提高 ,但它的抗光氧化性可能减弱。     

Genetic diversity of photosynthetic characters in native populations of Triticum dicoccoides

Wild emmer wheat (Triticum dicoccoides Korn) has shown wide genetic diversity for disease resistance and morpho-physiological traits of economic importance. Our objectives were to test for genetic variation (V_G) in photosynthetic characteristics residing within and between native populations sampled from three ecogeographical regions of Israel, and to identify potential sources of high photosynthetic efficiency for future wheat improvement. Accessions sampled in the center of wild emmer distribution (upper Jordan Valley) in a relatively narrow geographical range showed the greatest diversity in CO₂-assimilation rate per unit leaf area (A) or per unit chlorophyll (A/Chl). Genetic variation was absent for internal CO₂ concentration (Ci) and water-use efficiency (WUE) and generally lacking for stomatal conductance (gs). Leaf area, although quite variable, was not a significant cofactor in assessing genetic potential for photosynthesis. Accessions within a given population showed 10-times more variation in A and A/Chl than populations sampled from different locations in a region. Accessions with the highest photosynthetic efficiency were derived from upland steppic populations located in marginal habitats extending southward into Israel. Some accessions having high photosynthetic capacity (A=32 mol m^-2 s^-1) with no significant reduction in leaf size constitute a potentially valuable genetic resource yet untapped for genetic improvement of hexaploid (T. aestivum L.) wheat.Abbreviations LA total leaf area - V_G total genetic variance - PPFD photosynthetic photon flux density - WUE water-use efficiency     

两种生态型榕树的叶绿素含量、荧光特性和叶片气体交换日变化的比较研究

比较盆栽 生榕树和两栖型树的形态差异、叶片叶绿素含量、叶绿素荧光特性和气体交换的日变化。两栖型榕树具有较发达的气生根和水生不定根,叶片比陆生榕树宽,并有向中生性 倾向,陆生榕树的叶绿素含量比两栖榕树高,净光合速率略高于水培两栖型榕树,但明显高于土培两栖型榕树,蒸腾速率以水培两栖型树最高,陆生榕树次之,土培两栖型榕树最低,线性回归分析表明,三者的叶片气孔导度与净光合速率变化均呈正相关,气孔导度的变化     

Intraspecific variability of ecophysiological traits of four Magnoliaceae species growing in two climatic regions in China

Plants may change their ecophysiological traits to adapt to new environments, but the responses strongly depend on species and environmental conditions. Magnoliaceae species are of great scientific importance but are extremely endangered, therefore, it is crucial to study their ecophysiological adaptations for ex situ conservation. Here, we chose four common Magnoliaceae species growing in two botanical gardens located in south and north subtropical monsoon regions, and measured hydraulic and photosynthetic traits in both wet and dry seasons. We found that plants growing in north region showed significant lower leaf water potential at predawn and midday than those in south region, indicating that species suffered more severe drought stress in north region. As a result, species in north region had lower stomatal conductance and photosynthetic rates, as well as smaller stomatal pore index. In addition, significantly lower stem hydraulic conductivity of the two deciduous species in north region were observed compared with species in south region, while the two evergreen species at both regions showed similar values of stem hydraulic conductivity. Non-significant differences in leaf turgor loss points, leaf conductance, specific leaf area, and wood density were found when comparing species from the north and south regions. Our results suggested that the adjustment of plant hydraulics to local climatic conditions of Magnoliaceae species occurs primarily through changes in stomatal morphology and function, whereas the contribution of intraspecific variation in leaf hydraulic traits appears to be limited.