NaCl胁迫对葡萄砧木光合特性与叶绿素荧光参数的影响

为探究葡萄（Vitis sp.）砧木对盐胁迫的响应机制，以耐盐葡萄砧木品种101-14M（V. riparia×V. rupestris）和盐敏感品种188-08（V. berlandieri × V. riparia）的一年生苗为试材，比较研究了0、4、6、8、10 g·kg-1的NaCl胁迫对2种砧木叶片叶绿素含量、光合气体交换参数和叶绿素荧光参数的影响。结果表明：随着盐浓度升高，净光合速率、气孔导度、胞间二氧化碳浓度和蒸腾速率显著下降，同时最大荧光产量、最大光化学效率、实际光化学效率和光化学淬灭系数也呈下降趋势，初始荧光产量、非光化学淬灭系数和叶绿素含量表现为先升高后降低。在6 g·kg-1 NaCl胁迫下，188-08光合速率降低主因由气孔限制转向叶绿素限制，并在8 g·kg-1 NaCl胁迫下PSⅡ受到严重损伤；而101-14M叶片在8 g·kg-1盐胁迫下主要因叶绿素限制造成光合受限，并在10 g·kg-1盐胁迫下PSⅡ反应中心遭受损伤。     

MYB转录因子参与植物非生物胁迫响应与植物激素应答的研究进展

基因的时空表达受转录因子的精确调控。植物在面对不利环境因素比如高温、低温、干旱、盐碱等胁迫时其细胞生理生化会迅速地从“舒适”状态转变进入“胁迫响应”状态。这种快速响应的状态转变依赖于植物对胁迫信号的感知及传递、激素通路(脱落酸、茉莉酸等)的激发、转录因子的活化等复杂的过程;最终植物通过胁迫相关基因的表达、次生代谢转变、抗氧化物质的积累等实现胁迫条件下细胞内环境的再平衡从而获得生存。植物MYB(v-MYB avian myeloblastosis viral oncogene homolog)转录因子就是上述转变中的重要参与者。本文介绍了植物MYB转录因子的结构特征、分类,综述了近些年来MYB转录因子与非生物胁迫,以及植物激素应答过程相关的研究进展。     

c-GMP诱导对盐胁迫下番茄的转录组分析

以市场常见的番茄为材料,采用Illumina高通量测序技术对NaCl胁迫、c-GMP诱导以及两者组合处理下番茄幼苗进行转录组测序。结果表明:共获得83.35 Gb的原始数据,Q30碱基百分比在90.91%及以上,分别将各样品的原始读数与指定的参考基因组进行序列比对,比对效率从88.03%到92.74%不等。同时将得到的31 734条序列注释到不同的数据库(GO、KEGG、KOG、NR、Pfam、Swiss-Prot和egg NOG),通过GO数据库,将其划分到细胞组分、分子功能以及生物学过程三大注释类别下的51个亚功能组中,通过COG数据库与KEGG数据库将其分别注释到25个类别与128个代谢通路。在NaCl胁迫、c-GMP诱导以及两者组合处理下共发现SNP位点127 944个,其中仅有22.6%的SNP位点位于非编码区。差异基因结果显示,c-GMP能诱导盐胁迫下更多基因的表达。该转录组测序数据可靠,结果覆盖面广,为番茄c-GMP诱导盐胁迫下基因挖掘与功能研究提供了理论依据。     

不同水分条件下不同抗旱性苦荞根系生长规律研究

为了探明不同抗旱性苦荞根系形态和生理特性与抗旱性的关系,为干旱胁迫下苦荞高产优质栽培管理及抗旱品种的筛选提供理论依据,采用人工控水的方法,研究并分析了正常供水、重度干旱条件下不同抗旱性苦荞品种迪庆苦荞（耐旱）、黑丰1号（旱敏感）根系生长形态和生理指标变化。结果表明,干旱胁迫显著增加了苦荞根冠比、根系丙二醛（MDA）和脯氨酸（Pro）含量,而最大根长、根体积、根表面积显著降低。随着生育期推进,各处理苦荞最大根长、根体积、根表面积、MDA含量等指标均呈现逐渐增加趋势,根冠比、Pro含量呈现先增后减趋势。品种之间方差分析结果表明,重度干旱胁迫条件下,各测定时期迪庆苦荞的根冠比、最大根长、根体积、根表面积、根系Pro含量均显著高于黑丰1号,MDA含量则显著低于黑丰1号。回归分析表明,不同处理苦荞根表面积、最大根长等指标在测定时期内随时间变化的数学模型均符合指数函数,根体积、MDA含量等指标均符合一元二次方程的规律。干旱胁迫下苦荞根系与地上部分的生长均受到抑制,且表现为对地上部的影响大于对根系;与黑丰1号相比,迪庆苦荞耐旱性更强。     

低磷和铝毒耦合胁迫对杉木叶片抗坏血酸——谷胱甘肽循环的影响

为揭示抗坏血酸-谷胱甘肽(As A-GSH)循环在杉木适应低磷和铝毒胁迫中的作用,以耐低磷和铝毒胁迫的杉木家系YX3及对低磷和铝毒胁迫敏感的杉木家系YX12为试验材料,研究不同处理下[对照处理(CK)、低磷处理(-P)、铝处理(Al)和低磷加铝处理(-P+Al)]2个杉木家系叶片中As A-GSH循环代谢关键酶的变化规律。结果表明:不同胁迫处理下(-P、Al和-P+Al),2个杉木家系的丙二醛(MDA)含量均显著高于各自对照(-P处理下YX12叶片MDA含量除外),而且在Al和-P+Al处理下,耐性杉木家系YX3叶片中MDA含量均小于敏感型杉木家系YX12。进一步分析表明,与各自对照相比,不同胁迫处理增加了2个杉木家系叶片中的As A和DHA含量,同时提高了其叶片中抗坏血酸过氧化物酶(APX)、单脱氢抗坏血酸还原酶(MDHAR)、脱氢抗坏血酸还原酶(DHAR)、谷胱甘肽还原酶(GR)的活性,而且除DHA含量外,在-P、Al和-P+Al处理下耐性杉木家系YX3叶片中APX、GR、MDHAR、DHAR和As A含量均高于敏感型杉木家系YX12。此外,耐性杉木家系YX3叶片中还原型谷胱甘肽(GSH)含量以及As A/DHA值和GSH/GSSG值均高于敏感型家系YX12。因此,上述结果表明在不同胁迫条件下,杉木幼苗通过提高叶片抗氧化物质含量和As A-GSH循环关键酶活性来清除过量的活性氧,减轻胁迫诱导的氧化损伤;不同胁迫处理下,2个杉木家系叶片抗氧化物质含量及As A-GSH循环中关键酶活性响应的差异表明耐性杉木家系YX3具有较高的As A—GSH循环效率和抗氧化物质再生能力,从而有效抑制胁迫诱导的氧化损伤,这可能是其具有较强耐性的重要原因之一。     

2个与HSP70基因连锁的微卫星座位与牛运输应激性状的关联分析

试验探讨了2个与HSP70基因连锁的微卫星座位与牛运输应激性状的关联分析。选择120头12月龄、体重250 kg左右的健康西门塔尔杂种肉牛进行运输应激试验，并根据牛基因组遗传图谱，选择23号染色体上与HSP70基因连锁的微卫星座位BMS468和BM1258检测其在西门塔尔杂种肉牛样本群体中的多态性，采用最小二乘拟合一般线性模型分析微卫星座位与运输应激性状部分指标之间的关联效应。结果显示：微卫星座位BMS468共检测到5个等位基因（128、134、140、146、154 bp），优势等位基因为128和134 bp，有效等位基因数（Ne）、多态信息含量（PIC）和遗传杂合度（He）分别为3.66、0.68和0.73，遗传多态性较高，关联分析显示与运输后7 d平均日增重和发病率显著相关，其中128/128 bp基因型个体的运输后7 d平均日增重最大（P < 0.05），134/128 bp基因型个体的发病率最低（P < 0.05）；微卫星座位BM1258座位共检测到6个等位基因（99、101、103、113、117、119 bp），优势基因为101 bp，Ne、PIC和He分别为4.30、0.73和0.77，遗传多态性较丰富，关联分析显示，其与发病率显著相关，其中99/99 bp基因型个体的发病率最低（P < 0.05）。综上所述，2个微卫星座位可作为牛运输应激性状的潜在遗传标记，为开展牛抗运输应激性状的标记辅助选择提供科学依据。     

Exogenous application of allelopathic water extracts helps improving tolerance against terminal heat and drought stresses in bread wheat (Triticum aestivum L. Em. Thell.)

The allelopathic water extracts (AWEs) may help improve the tolerance of crop plants against abiotic stresses owing to the presence of the secondary metabolites (i.e., allelochemicals). We conducted four independent experiments to evaluate the influence of exogenous application of AWEs (applied through seed priming or foliage spray) in improving the terminal heat and drought tolerance in bread wheat. In all the experiments, two wheat cultivars, viz. Mairaj‐2008 (drought and heat tolerant) and Faisalabad‐2008 (drought and heat sensitive), were raised in pots. Both wheat cultivars were raised under ambient conditions in the wire house till leaf boot stage (booting) by maintaining the pots at 75% water‐holding capacity (WHC). Then, managed drought and heat stresses were imposed by maintaining the pots at 35% WHC, or shifting the pots inside the glass canopies (at 75% WHC), at booting, anthesis and the grain filling stages. Drought stress reduced the grain yield of wheat by 39%–49%. Foliar application of AWEs improved the grain yield of wheat by 26%–31%, while seed priming with AWEs improved the grain yield by 18%–26%, respectively, than drought stress. Terminal heat stress reduced the grain yield of wheat by 38%. Seed priming with AWEs improved the grain yield by 21%–27%; while foliar application of AWEs improved the grain yield by 25%–29% than the heat stress treatment. In conclusion, the exogenous application of AWEs improved the stay green, accumulation of proline, soluble phenolics and glycine betaine, which helped to stabilize the biological membranes and improved the tolerance against terminal drought and heat stresses.     

Zerumbone attenuates MPP+-induced cytotoxicity in human neuroblastoma SH-SY5Y cells by inhibition of oxidative stress

AIM: To investigate the role of zerumbone (ZER) in 1-methyl-4-phenylpyridinium (MPP⁺)-induced cytotoxicity of human neuroblastoma SH-SY5Y cells. METHODS: Human neuroblastoma SH-SY5Y cells were cultured in vitro and the protective effect of ZER against MPP⁺-induced cytotoxicity was measured by CCK-8 assay. Flow cytometry was used to determine the apoptosis and reactive oxygen species (ROS). The expression of Parkinson disease protein 7 (PARK7) was knocked-down by using PARK7-specific short hairpin RNA (shRNA). The protein levels of PARK7, nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) were determined by Western blot. RESULTS: MMP⁺ remarkably reduced the cell viability in a dose-dependent and time-dependent manner. The SH-SY5Y cell injury model was established by treatment with MPP⁺ at 600 μmol/L for 24 h. ZER up-regulated the protein levels of PARK7 and Nrf2 (P<0.05), alleviated apoptosis (P<0.05), and reduced ROS production (P<0.05) in the SH-SY5Y cell injury model. Meanwhile, N-acetyl-L-cysteine (NAC) had the similar functions. Moreover, significant reductions in the protein levels of Nrf2 and HO-1 (P<0.05), and obvious increases in apoptosis (P<0.05) and ROS level (P<0.05) were demonstrated in PARK7-knockdown cells. CONCLUSION: ZER protects SH-SY5Y cells against MPP⁺-induced cytotoxi-city, which may be related to activation of PARK7/Nrf2/HO-1 pathway, and subsequent attenuation of oxidative stress and apoptosis.     

Root distribution patterns of peanut genotypes with different drought resistance levels under early‐season drought stress

Drought severely limits crop yield of peanut. Yet cultivars with enhanced root development enable the exploration of a greater volume of soil for water and nutrients, helping the plant survive. Root distribution patterns of three genotypes (ICGV 98305, ICGV 98324 and Tifton‐8) were compared when grown in well‐watered rhizoboxes and when grown in rhizoboxes where an early‐season drought was imposed using rain‐exclusion shelters. The treatments were arranged in a completely randomized design with three replications, and the experiment was conducted during two seasons at the Field Crop Research Station of Khon Kaen University, in Khon Kaen, Thailand. The root system of ICGV 98305, when grown under drought, had a significantly higher root length in the 30–110 cm deep soil layers and less roots in the 0–30 cm soil layers when under drought than when grown under well‐watered conditions. Roots of Tifton‐8 had the largest reductions in root length in upper soil layer and reduced in most soil layers. Tifton‐8 grown under drought was smaller than under well‐watered control for all root traits, showing negative response to drought. The peanut genotypes with high root traits in deeper soil layer under early‐season drought might contribute to drought avoidance mechanism.     

Effects of prebiotic mannan oligosaccharide on the growth,survival, and anxiety-like behaviors of zebrafish (Danio rerio)

A study was designed to investigate the possible positive prebiotic effects of mannan oligosaccharides (MOS) on growth and reduction of anxiety behaviors in zebrafish (Danio rerio). The experimental diets were supplemented with 0, 2, 4, 6, or 8 g MOS kg^?1 and were fed to juvenile fish (0.47 ± 0.017 g) in triplicates for six weeks. Significant differences were found in the final body weight, body weight intake, percent body weight intake, and specific growth rate among treatments. The regression analyses showed that the optimum MOS level was 4–4.1 g MOS kg^?1 diet. Fish fed 4 g MOS kg^?1 feed showed higher survival than the other treatments. Also, using the novel tank test, fish fed with 4 g MOS kg^?1 diet showed lower anxiety by swimming in the upper portion of the tank. The other behavior parameters remained unaffected by the prebiotic. The results indicated the beneficial effect of the prebiotic MOS on growth and partly on welfare of zebrafish juveniles.