Evaluation of Chlorophyll Content and Fluorescence Parameters as Indicators of Drought Tolerance in Barley

Drought is a major abiotic stress that severely affects food production worldwide. Agronomic and physiological traits associated with drought tolerance are suitable indicators for selection of drought tolerance genotypes to reduce the impact of water deficit on crop yield in breeding program. The objective of this study was to identify indicators related to drought tolerance through analysis of photosynthetic traits in barley （Hordeum vulgare L.）. These traits included chlorophyll content, initial fluorescence （Fo）, maximum primary yield of photochemistry of photosystem Ⅱ （Fv /Fo） and maximum quantum yield of photosystem Ⅱ （Fv/Fm）. Four genotypes （Tadmor, Arta, Morocco9-75 and WI2291） variable in drought tolerance were used to investigate the correlation between these traits and drought tolerance. The results reflected that all of these traits were affected negatively in the four genotypes at different levels of post-anthesis drought stress, but the decrease in drought tolerant genotypes was much less than that of drought sensitive genotypes. The results further revealed that the components of the photosynthetic apparatus could be damaged significantly in drought sensitive genotypes, while drought tolerant genotypes were relatively less affected. On the other hand, the values of chlorophyll content, Fo, Fv/Fo and Fv/Fm in drought tolerance genotypes were significantly higher than those in drought sensitive genotypes under drought stress. It was concluded that chlorophyll content, Fo, Fv/Fo and Fv/Fm could be considered as reliable indicators in screening barley germplasm for drought tolerance.

Alleviation of Al Toxicity in Barley by Addition of Calcium

The potential mechanism by which Ca alleviates Al toxicity was investigated in barley seedlings. It was found that 100 Al-alone treatment inhibited barley plant growth and thereby reduced shoot height and root length, and dry weights of root, shoot and leaf; promoted Al accumulation but inhibited Ca absorption in plant tissues; and induced an increase in the activities of superoxide dismutase （SOD）, catalase （CAT）, and peroxidase （POD） and in the level of lipid peroxidation （MDA content） in leaves. Except for the increase in Ca concentration in plant tissues, treatment with 0.5 mM Ca in the absence of Al had less effect on the above-mentioned parameters, compared with the control. Addition of Ca efficiently reduced Al toxicity, which is reflected by the promotion of plant growth, reduction in Al concentration and MDA content, increase in Ca concentration and in SOD, POD, and CAT activities compared with the Al-alone-treatment; with increase in Ca level （3.0 raM）, the ameliorative effect became more dominant. This indicated that the alleviation of aluminum toxicity in barley seedlings with Ca supplementation could be associated with less absorption of Al and the enhancement of the protective ability of the cell because of increased activity of the antioxidative enzyme.

Effects of Waterlogging on Photosynthesis and Antioxidant Enzyme Activities of Six Barley Genotypes with Different Waterlogging Tolerance

A field experiment was carried out to study genotypic difference in the effect of waterlogging on photosynthesis, chlorophyll content and antioxidative enzyme activities in barley. Waterlogging caused a rapid decline in net photosynthetic rate (Pn) and stomatal conductance (gs), and little change in chlorophyll content during early days of the treatment. A dramatic increase in malondialdehyde (MDA) content, superoxide dismutase (SOD) and peroxidase (POD) in waterlogged plants in the early days of the experiment was found, indicating the occurrence of oxidative stress in barley plants exposed to waterlogging. There was a highly significant difference in the changed extent of all these parameters among genotypes. Franklin and Yongjiahong Liuleng Damai, which were relatively sensitive to waterlogging in terms of growth, photosynthesis and chlorophyll content, accumulated much more MDA than the other two relatively tolerant genotypes (93-3143 and QS). After removal of waterlogging, the genotypic difference became much greater in recovering of these examined parameters. Yongjiahong Liuleng Damai showed higher recovery, while Franklin only recovered to 50% of the control at the 14 day after waterlogging removal. It may be concluded that it is the difference in anti-oxidative stress caused by waterlogging that account for the major difference in photosynthesis among barley genotypes.

Genotypic and Environmental Variations of Arabinoxylan Content and Endoxylanase Activity in Barley Grains

Arabinoxylan （AX） content in barley grains is an important quality determinant when barley is used as raw material of malt or beer production. The cultivar and environmental variations of total arabinoxylan （TAX）, water extractable arabinoxylan （WEAX） and endoxylanase activity （EA） were investigated using eight barley cultivars growing at seven locations with diverse environmental conditions. The results showed that both barley cultivar and location significantly affected the TAX, WEAX and EA levels, but the variations of TAX content and EA were mainly attributed to cultivar, while the impact of location on WEAX content was greater than that of cultivar. Correlation analysis indicated that TAX was significantly correlated to WUAX.

Genotypic Difference in Plant Growth and Mineral Composition in Barley Under Aluminum Stress

Four barley genotypes (Tiantaiyangdamai, Xiyin2, Mimaill4 and Tai94-Ce6) were exposed to 0, 50, 100, and 150μM of Al-containing solution with pH 4.5, to determine the differences in growth inhibition , Al concentration and accumulation and mineral composition among genotypes. The results showed that Mimaill4 and Tai94-Ce6 had significantly higher Al concentration and accumulation than Tiantaiyangdami and Xiyin2, especially in roots, and the growth traits including root and shoot dry weights, shoot height, root length and tillers per plant were more inhibited in the former two genotypes. Al treatments caused a significant reduction of N, P, K, Ca, Mg and Mn content in both roots and shoots, of Cu in shoots; and a significant increase in Fe and Zn content in both roots and shoots, of Cu in roots. The changed rates of mineral content caused by Al treatments, in terms of the content in 150μM Al divided by the content in the control, differed significantly among four genotypes. Two Al-sensitive genotypes, Mimaill4 and Tai94-Ce6 had much greater changes in mineral content than other two Al-tolerant genotypes Tiantaiyangdamai and Xiyin2 when subjected to Al stress in comparison with the control. It is indicated that the Al-tolerant genotype is characterized by less uptake and accumulation of Al in roots and smaller disorders in mineral metabolism and ion homeostasis.

Variation of Grain and Malt Qualities in Barley as Affected by Cultivars and Environments

Inferior and unstable quality of malt barley in China has limited its wide use in malting and brewing industries. In this research, eight two-rowed barley cultivars were planted at 7 locations with different ecological conditions in southern China, to investigate the cultivar and environmental effect on grain and malt qualities. The results showed that grain protein content differed dramatically among locations, but there were no significant differences among cultivars. For four malt qualities including diastatic power, wort viscosity, Kolbach index and malt extract, significant differences were found among cultivars and locations, except for diastatic power among cultivars. Coefficients of variance(CV)caused by location were greater than those caused by cultivar for each quality parameter, especially for diastatic power and Kolbach index, indicating the predominant influence of environment on malt quality. The analysis showed that grain protein content was positively related to diastatic power and wort viscosity, and negatively to malt extract. Kolbach index was positively related to malt extract, and negatively to diastatic power and wort viscosity. Diastatic power showed positive and negative correlation with wort viscosity and malt extract, respectively.

Cultivar and Environmental Effects on p-glucanase Activity in Both Barley Grain and Malt and Its Function in β-glucan Degradation

Eight two-rowed barley cultivars were grown at seven locations in the southern winter-barley zone of China. Mean grainβ-glucanase activity ranged from 39.89 U kg-1 for Suyin2 to 49.75 U kg-1 for Xi-umai3 in 8 cultivars grown at 7 locations, and from 38. 74 U kg-1 in Zhengzhou to 57. 96 U kg-1 in Putian among 7 locations on an average of all cultivars. Correspondingly, mean malt β-glucanase activity of 8 cultivars ranged from 313.33 U kg-1 for ZAU3 to 489. 89 U kg-1 for Daner Barley, and of 7 locations from 330.40 U kg-1 in Yancheng to 418. 24 U kg-1 in Putian. There were significant differences among cultivars and locations in maltβ-glucanase activities. The locations showed much larger variation in maltβ-glucanase activities than cultivars. The reduction of total β-glucan content after malting varied in both cultivars and locations, with a mean of 78.31%. The analysis of correlations showed that maltβ-glucan content was significantly positively and negatively correlated with grain β-glucan content and malt β-glucanase activity, respectively, and malt β-glucanase activity was significantly positively correlated with grain β-glucanase activity.

The influence of drought stress on malt quality traits of the wild and cultivated barleys

As a major abiotic stress,drought causes instability and deterioration of malt barley quality.There is distinct difference among barley cultivars in the responses of the main malt quality traits to drought stress.In the previous study,we identified some Tibetan wild barley accessions with relatively less change of malt quality traits under drought.In this study,we examined the impact of drought stress during grain filling stage on grain weight and several important malt quality traits,including total protein content,β-glucan content,limit dextrinase activity,β-amylase activity,and protein fractions in four barley genotypes(two Tibetan wild accessions and two cultivars).Drought treatment reduced grain weight,β-glucan content,and increased total protein content,β-amylase activity.These changes differed among barley genotypes and treatments,and are closely associated with grain filling process and kernel weight.All the results indicated Tibetan wild barley had great potential for developing drought tolerant barley cultivars.Relatively stable kernel weight or filling process under water stress should be highlighted in malt barley breeding in order to reduce the effect of water stress on malt barley quality.

Relationship of Grain Fructan Content to Degree of Polymerisation in Different Barleys

Fructans are important in the survival of plants and also valuable for humans as potentially health promoting food ingredients. In this study fructan content and composition were determined in grains of 20 barley breeding lines and cultivars with a wide variation in chemical composition, morphology and country of origin, grown at one site in Chile. There was significant genotypic variation in grain fructan content ranging from 0.9% to 4.2% of grain dry weight. Fructan degree of polymerisation (DP) was analysed using high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Changes in the distribution of different chain lengths and the pattern of structures of fructan were detected with increasing amount of fructan in the different barleys. A positive correlation was found between fructan content and the relative amount of long chain fructan (DP > 9) (r = 0.54, p = 0.021). Our results provide a basis for selecting promising barley lines and cultivars for further research on fructan in barley breeding with the aim to produce healthy food products.

Assessing the product quality and biological activities of barley(Hordeum vulgare L.)grasses at different harvest times

Barley(Hordeum vulgare L.)grasses(BG)have attracted considerable interest due to their multiple physiological activities and health benefits.In this paper,eight BG at four different growth stages were collected:seedling,tillering,stem elongation,and heading,and their product qualities and biological activities were examined and studied.Results demonstrated that harvest time obviously influenced proximate composition,surface color,and amino acid profile.Z21 and Z23 harvested at the seedling and early tillering stages,respectively,had higher total phenolic content(TPC)and total flavonoid content(TFC)than the other BG.Moreover,Z21 and Z23 possessed better DPPH radical-scavenging ability,antioxidant capacity,andα-glucosidase inhibitory activity,which were positively correlated with TPC,TFC,and protein and total amino acid contents.Our findings suggested that the early tillering stages were the preferable harvest times for BG with good product quality and biological properties.

大麦种子萌发lncRNA-miRNA-mRNA差异表达分析及ceRNA调控网络构建

为解析长链非编码RNA(lncRNA)、microRNA(miRNA)和mRNA如何在ceRNA互作模式下调控大麦种子萌发,揭示大麦(Hordeum vulgare L.)种子萌发转录水平分子调控机制,基于大麦种子萌发相关的RNA-Seq数据,共鉴定出6447个差异表达的mRNA,661个差异表达的lncRNA,310个差异表达的miRNA;对差异表达的mRNA和lncRNA进行加权基因共表达网络(WGCNA)分析,各鉴定到1个与大麦种子萌发高度相关的共表达模块。模块内相关基因涉及水分响应、胚发育等生物学过程,以及MAPK信号转导、植物激素信号转导等信号通路。通过对lncRNA/mRNA和miRNA进行靶基因预测,得到168个miRNA-mRNA靶基因对以及310个miRNA-lncRNA靶基因对,进而构建了包含2个子网络的ceRNA调控网络,发现有16个miRNA、38个lncRNA以及18个mRNA可能具有ceRNA功能。最后,利用qRT-PCR验证了2个关系对:HORVU0Hr1G039470-miR2611-MSTRG.21252以及HORVU6Hr1G031480-miR1858-MSTRG.23227。

NaCl胁迫对青稞种子萌发及幼苗生长的影响

以西藏自治区5个青稞(Hordeum vulgare L. var. nudum Hook. f.)品种为试验材料,研究不同NaCl浓度对青稞种子萌发及幼苗生长的影响,并且对不同青稞品种耐盐性进行评价分析。结果表明,NaCl浓度为0.1%时对青稞萌发及幼苗生长具有一定的促进作用;当浓度增至0.5%时,种子的发芽势、发芽率、活力指数以及幼苗的根长、芽长、根鲜重均显著下降;当浓度为1.0%时,隆子黑青稞与苟芝紫青稞已丧失发芽能力。总体来看,5个青稞品种中,喜拉22耐盐性最好,其次是藏青320、藏青2000、苟芝紫青稞,隆子黑青稞耐盐性最弱。

GREEN PLANT REGENERATION FROM PROTO PLASTS OF BARLEY (Hordeum vulgate L.)

Barley is the world’s fourth leading cereal in acreage planted, after wheat, rice and corn. Nevertheless, whilst plant regenerations from protoplast cultures of rice, corn and wheat were realized one after another during the past few years, only albinos were regenerated sporadically from barley protoplasts. The present note reports that a group of complete green plants has been obtained from protoplasts isolated from cell suspension cultures in barley.

人工老化对大麦种子活力及其萌发早期淀粉分解和内源激素的影响

【目的】研究老化处理对大麦种子活力及其萌发早期胚乳淀粉粒类型、淀粉含量、淀粉酶活性及内源激素的影响。【方法】采用高温高湿的人工老化处理方法。【结果】人工老化使4个大麦品种的发芽特性指标和种胚活力均逐渐降低。萌发72 h的种子胚乳中小淀粉粒数目增加,大淀粉粒数目减少,淀粉质量分数增加。随着老化时间的延长,α-淀粉酶、β-淀粉酶和极限糊精酶活性均呈降低的趋势,且老化15 d的种子淀粉酶活性显著低于对照;萌发24 h,GA_3含量显著低于对照,萌发48~72 h,GA_3含量均高于对照。ABA含量在萌发过程中均高于对照。【结论】人工老化打破了萌发过程中GA_3和ABA间的平衡,导致淀粉酶活性降低,淀粉分解减缓,进而使大麦种子活力降低,萌发受到抑制。

萌发温度及品种对青稞种子萌发和幼苗生长的影响

以黑、白、墨绿和花4个青稞品种为试验材料,研究温度对青稞种子萌发特性和幼苗生长的影响,分析了不同温度下不同青稞品种种子萌发特性的差异。结果表明,各样品的发芽势、发芽率和发芽指数指标均在10～25℃范围内随着温度的升高而升高,在25℃时达到最大值;30℃时青稞种子萌发指标均呈小幅下降。同时,青稞幼苗的生长情况和生物量也是在25℃时达到最佳。因此,青稞种子萌发和幼苗生长的最适温度较低,为25℃。对于不同品种,在同一处理温度下,种子萌发指标和幼苗生长、生物量指标的高低顺序为黑青稞>墨绿青稞>花青稞>白青稞。由于低温影响种子的萌发进程和幼苗生长,因此在实际生产中对低萌发率、生长迟缓的种子要特别注意选择适宜的播种期。

干旱胁迫对大麦幼苗根系的影响

为了解干旱胁迫对大麦幼苗根系生长的影响,采用盆栽称重控制土壤含水量的方法,测定了土壤含水量为田间持水量的85%、55%、45%和35%等4个处理下,4个抗旱性不同的大麦品种的幼苗根系形态和根系吸收能力等相关指标。结果表明,随着土壤含水量的减少,大麦幼苗的最长种子根、根尖数、根组织含水量均呈下降趋势;根分支数和根冠比总体呈上升趋势;根鞘大小和根毛密度整体上呈先上升后下降的趋势;根系活力与根总吸收面积和根活性吸收面积之间存在一定的互补效应。抗旱性较强的大麦品种较抗旱性较弱的品种,在干旱胁迫下能够保持更庞大的根系、更大的根-土交互面和更高的根系吸收能力。幼苗根系形态可以作为大麦耐旱性的筛选指标。

引发对老化大麦种子可溶性物质及抗氧化酶活性的影响

为探讨聚乙二醇(PEG)和氯化钙(CaCl2)溶液引发对老化大麦种子活力的影响,本研究采用人工加速老化法对大麦种子进行处理,以人工老化程度为高活力、中活力、低活力的大麦种子为试材,采用PEG和CaCl2引发的最佳方式(与对照差异极显著)进行处理,并分析种子胚中可溶性糖含量和可溶性蛋白含量以及SOD、POD和CAT活性变化的趋势。结果表明:引发显著增加了老化大麦种子中可溶性糖含量和可溶性蛋白含量,显著提高了SOD、POD和CAT酶活性,而且随吸胀时间变化种子中贮藏物质含量和部分酶活性的变化趋势各不相同,在不同的引发方式中,20%PEG和10 mg·L^-1 CaCl2引发24 h效果最显著。这表明种子引发能够修复种子老化损伤和提高种子萌发过程中的酶活性。

种子成熟度对大麦种子活力的影响

【目的】分析大麦种子成熟度对种子活力的影响,研究不同品种的最佳收获期。【方法】选取不同成熟度的P13-3和甘啤4号大麦种子,恒温发芽试验测定电导率。发芽前测定不同成熟度种子的长度、宽度、厚度、千粒鲜重、千粒干重和含水量等物理指标,发芽过程中测定发芽势、发芽率、发芽指数、活力指数、幼苗苗长、幼苗根长、幼苗鲜重和幼苗干重等种子活力指标。【结果】随着成熟度的增加,两个大麦品种种子均为先增长,后增宽,最后增厚;千粒鲜重、千粒干重、含水量和电导率差异显著,含水量随着成熟度的增加呈下降并趋于平稳的趋势;苗长、根长、幼苗鲜重、发芽指数和活力指数呈先增加后降低的趋势,除幼苗干重外,其余活力指标均达到差异显著水平。【结论】种子成熟度对种子活力有较大影响,其中千粒干重、电导率、幼苗鲜重、苗长和根长可作为检验种子活力的参考指标。P13-3种子在开花后36~42d,甘啤4号种子在开花后30d活力相关指标较好,幼苗质量较好,为适宜收获期。

不同醇溶液对青稞种子萌发及生长的影响

为促进青稞(Hordeum vulgare var. coeleste L.)种子的活力和幼苗产量,研究了不同醇溶液(1%的甲醇、乙醇、丙醇、正丁醇)对青稞种子萌发及幼苗生长的影响。结果表明,与对照相比,1%不同醇溶液处理对青稞种子萌发和幼苗生长具有明显影响。1%甲醇对青稞种子的萌发和幼苗生长均起促进作用,其发芽率、发芽势、发芽指数分别比对照组高1.11、1.11个百分点和1.12,幼苗叶绿素a、叶绿素b、总叶绿素分别比对照组高0.013 7、0.000 4、0.000 7 mg/g,以及幼苗的苗高、根长分别比对照组高2.15、3.51 cm;1%乙醇溶液也对种子萌发有明显促进作用,且效果优于1%甲醇溶液,其发芽率、发芽势、发芽指数分别比对照组高4.44、5.56个百分点和6.86,但1%乙醇溶液抑制青稞幼苗的生长;1%丙醇、1%正丁醇溶液则对青稞种子的萌发及幼苗生长都起不同程度的抑制作用,1%正丁醇溶液抑制程度最强。研究表明,1%甲醇溶液对青稞种子的萌发及幼苗生长均起到促进作用。

Cd胁迫对11个青稞品种种子萌发和幼苗生长的影响

重金属污染土壤的修复治理工作迫在眉睫。为研究适合在青藏高原种植的Cd污染土壤修复植物,以11个青稞品种为试验材料,研究不同浓度Cd(0,5,10,20,40,80,160和320 mg/L)胁迫对青稞种子萌发情况及幼苗生长的影响。结果显示,(1)重金属Cd对青稞种子萌发表现出低浓度[ρ(CdCl_(2))=20 mg/L]促进和高浓度(ρ(CdCl_(2))≥80 mg/L)抑制效应;Cd胁迫对青稞幼苗生长过程的抑制效应强于种子萌发过程。(2)11个品种青稞种子耐Cd胁迫能力加权隶属函数D值依次为‘昆仑14号’>‘昆仑10号’>‘黑青稞’>‘柴青1号’>‘门农1号’>‘门源亮兰’>‘昆仑15号’>‘北青3号’>‘昆仑12号’>‘肚里黄’>‘北青6号’。结果表明:‘昆仑14号’及‘昆仑10号’对重金属Cd的耐受性最强,能较好地适应重金属土壤环境,具有作为青藏高原地区Cd污染土壤修复植物的潜力。