Selection parameters for resistance to Fusarium oxysporum f. sp. cubense race 1 and race 4 on diploid banana (Musa acuminata Colla)

Summary Shoot tip cultures from banana clones susceptible and resistant to Fusarium oxysporum f. sp. cubense (FOC) race 1 and race 4 were grown in vitro in the presence of different concentrations of fusaric acid and fungal crude filtrates or inoculated with a conidial suspension of FOC to assess correlation between in vivo and in vitro behaviour. Explants were susceptible to both filtrate and fusaric acid irrespective to their known field resistance/susceptibility response. No clear linkage between in vivo and in vitro behaviour was observed and our results suggest that the use of crude filtrate or non-host specific toxin (fusaric acid) in a screening programme for selecting a novel resistant genotype of Musa to FOC is not feasible. When peroxidase activity was used as a parameter to discriminate between sesceptibility and tolerance, results were in good agreement with field response of host plant to pathogens. Early enzymatic activity increased in the incompatible host-pathogen interaction but not in the compatible interaction.Abbreviations IBA Indolebutyric acid - 2iP 6-dimethylallylamino-purine - VCG Vegetative Compatibility Group - FOC Fusarium oxysporum f. sp. cubense - IEF isoelectrofocusing     

孕穗期低温对玉米雌穗的伤害作用

在孕穗期（播种后６５天），玉米植株经１０℃低温处理２天和５天后，雌穗超氧物歧化酶（ＳＯＤ）活性下降，膜脂过氧化作用增强，对生物膜系统产生直接伤害，电解质外渗率增大，电镜下可观察到线粒体、细胞质膜破坏、胞间连丝膨大变形，甚至断裂；粗糙内质网卷曲成空心圆状，进而引起生理代谢紊乱，使可溶性糖和游离氨基酸含量增加，淀粉、蛋白质含量下降，阻碍雌穗发育，减少穗粒数，引起减产。     

Genetic Variability of Rubisco in Tetraploid Wheats (Triticum turgidum)

Nineteen tetraploid wheats (Triticum turgidum), differing in their agronomical behaviour and geographic origins were grown in two experiments and analysed for the following physiological traits: soluble leaf protein content, rubisco content, initial and potential carboxylase activities of this enzyme as well as its relative content in percentage of protein, the specific activity of the enzyme and its activation state. The results show a high genetic variability for all studied traits and more particularly for the initial carboxylase activity. High phenotypic correlation was observed between the rubisco content and its potential activities, in the first experiment. Correlation between souble leaf protein and rubisco content was significant in 9 genotypes of the second experiment.     

Characterization of cytoplasmic male sterility in Petunia hybrida. I. Localization,composition and activity of esterases

Summary Anthers of male fertile, cytosterile and restored male fertile clones of Petunia hybrida were compared for esterase activity and composition in subsequent stages of microsporogenesis. Three methods were applied (i) ultra-thin layer isoelectric focussing on polyacryl amide gels, (ii) quantitative spectrophotometrical assay, (iii) histochemical determination of total esterase activity associated to the azo-coupling method (Pearse, 1972).In male fertile and restorer idiotypes the isozyme patterns were quite similar. Both the number and intensity of bands increased gradually till the tetrad stage. In contrast, esterase activity in cytosterile anthers remained at a low level and hardy any new bands showed up in later stages. This unvariable, low activity level in cytosterile anthers was also found in the spectrophotometric assay. Histochemical determinations revealed that in male fertile anthers esterase activity is concentrated in the outer tapetal layer at late prophase and that it accumulates there till the early microspore stage. In male sterile anthers esterase accumulation in the tapetal cells stops at the moment that tapetal breakdown becomes visible. This suggests that differences in esterase activity and composition are an effect rather than a cause of the failing pollen formation.     

刺槐、木荷水浸液对马尾松幼苗生理活性的化感效应

用枯落物浸提液生物鉴定的方法,研究了刺槐、木荷对马尾松幼苗生理活性的化感影响。结果表明,两供体植物对受体光合色素含量和质膜相对透性的影响,总体表现为促进作用;对受体光合速率和蒸腾速率的影响,表现为抑制效应。供体木荷对氮、磷吸收的影响表现出低促高抑的作用趋势,对钾元素的吸收,均表现出一定的促进效应;而供体刺槐对氮、钾吸收的影响,则表现出高促低抑的作用趋势,对磷吸收的影响则相反。     

不同PEG-6000浓度处理下几种冷季型草坪草抗旱性比较研究

研究了3种冷季型草坪草的6个品种在PEG-6000模拟干旱胁迫条件下的生长表现和生理指标。结果表明：高羊茅的“家园”品种在干旱胁迫条件下具有较好的生长表现、在土壤中的根系分布最深、且能维持较高过氧化氢酶活性，表明其与其他供试品种相比具有较强的抗旱能力。     

甜菜子叶期幼苗硝态氮吸收特性及其与硝酸还原酶活性的关系

６个有代表性的甜菜品种在人工气候室的营养液培养试验表明，甜菜子叶期幼苗对ＮＯ３＾－的吸收要经最初２ｈ的适应阶段后才可均匀进行。均匀吸收后，观察到多倍体的吸收量〉２倍体，倍性相同品种中Ｅ型〉ＮＥ型〉ＮＺ型〉Ｚ型的初步结果。不同类型品种间ＮＯ３＾－吸收的表观米氏常数（Ｋｍ，ａｐｐ）、最大吸收速率（Ｉｍ）有明显差异，除多倍体ＮＺ型品种甜研３０１的Ｋｍ，ａｐｐ较低而Ｉｍ较高外，其余品种的Ｋｍ，ａｐｐ和Ｉｍ     

低温层积过程中圆齿野鸦椿种子的生理生化变化

通过对不同层积时间圆齿野鸦椿种子萌发及其生理生化变化情况的研究,得出种皮对圆齿野鸦椿种子萌发具有很强的机械障碍,仅通过低温层积不能完全解除种皮的机械障碍.低温层积配合60℃温水浸种能够有效解除休眠.同时通过实验发现,当采取播前温水处理打破种皮机械障碍时,以低温层积90～120 d为宜,层积时间过长会导致萌发率降低.通过实验,对低温层积不同时间的圆齿野鸦椿种子生理生化变化情况进行测定,结果表明:随着层积时间增加,可溶性糖含量与G-6-PDH和6-PGDH联合酶活性波动上升,而淀粉含量波动下降.说明种子内含物质相互转化,逐步解除休眠,同时种子呼吸代谢中戊糖磷酸途径所占比重上升.POD活性先逐渐上升,在120 d后活性下降,笔者认为这可能是导致层积120 d后种子萌发率降低的主要原因.     

关于水稻穗芽的生理学研究

利用重组自交系籼稻中-156/谷梅2号304份株系为材料，在田间条件下营造高温、高湿的小气候，以“穗穗芽率”及“粒穗芽率”为指标，筛选易发生穗芽与不易发生穗芽的极端材料，比较研究重组自交系亲本与各供试株系籽粒在穗芽发生期间的生理差异。结果表明，该重组自交系母本谷梅2号比父本中-156易穗芽，在正常成熟过程中籽粒内源GA₁含量水平高于中-156，ABA含量水平低于中-156；谷梅2号籽粒淀粉酶活性也高于中-156。花后15 d至完熟的籽粒灌浆期如遇高温、高湿条件，谷梅2号及易穗芽的株系籽粒内源GA1随雨日渐增，增幅高于中-156及不易穗芽的株系，同时其淀粉酶活性回升，在正常成熟过程中花后15 d后籽粒中淀粉酶活性与日渐降，但其幅度远高于父本中-156及不易穗芽的株系，这种变化可能是易穗芽的亲本与株系对高温、高湿敏感诱发穗上发芽的主要生理基础。     

Overexpression of a small heat‐shock‐protein gene enhances tolerance to abiotic stresses in rice

Rice (Oryza sativa L.) is one of the most important crops in the world which survives from various abiotic stresses in natural environments with specific stress‐involved genes expressed. Plant sHSPs (small heat‐shock proteins) were reported to respond to abiotic stresses. To improve the understanding of sHSPs in rice, we characterized heat‐shock‐protein gene OsHSP18.6 here. OsHSP18.6 could be induced by diverse stresses, such as drought, salt and cold, especially under heat. The gene was found expressed in root, stem, leaf, internode and spikelet. Overexpression of OsHSP18.6 results in increased thermotolerance and exhibits universal tolerance to stresses tested, including heat, drought, salt and cold. Lower levels of malondialdehyde (MDA) and greater activities of catalase (CAT) and superoxide dismutase (SOD) were observed in OsHSP18.6‐overexpression rice under heat and drought. OsHSP18.6‐overexpression lines indicated decreased sterile rates under hot weather without remarkable changes in most of other agronomic traits compared with wild‐type plants.