Establishment and Optimization of the Regeneration System of Mature Embryos of Maize （Zea mays L.）

A reliable system was developed for regeneration from mature embryos derived from callus of four maize inbred lines （Liao 7980, Dan 9818, Dan 340, and Dan 5026）. The protocol was mainly based on a series of experiments involving the composition of culture medium. We found that 9 pM 2,4-dichlorophenoxyacetic acid in MS medium was optimum for the induction of callus. The induction frequency of primary calli was over 85% for four inbred lines tested. The addition of L- proline （12 mM） in subculture medium significantly promoted the formation of embryogenic callus but it did not significantly enhance growth rate of callus. Efficient shoot regeneration was obtained on regeneration medium containing 2.22 μM 6- benzylaminopurine in combinations with 4.64 μM Kinetin. Regenerated shoots were rooted on half-strength MS medium containing 2.85 μM indole-3-butyric acid. This plant regeneration system provides a foundation for genetic transformation of maize.     

The Effects of Low Phosphorus Stress on Morphological and Physiological Characteristics of Maize （Zea mays L.） Landraces

A field trial was conducted to investigate main morphological and physiological changes of different maize landraces to low-P stress at the stage of seedling. P-deficiency significantly decreased root volume, total leaf area, and plant dry weight, but greatly increased density of root hairs and root top ratio. In addition, P-deficiency induced the significant enhancement of phosphorus utilization efficiency and the amount of proline, malondialdehye （MDA）, acid phosphatase （APase）, peroxidase （POD） and superoxide dismutase （SOD）, but the significant reduction of P uptake and soluable protein content. Since P-deficiency had smaller effects on the P-tolerant maize landraces DP-44, DP-32 and DP-33 as compared with P-sensitive landraces DP-29 and DP-24, it was demonstrated that differences of tolerance to P-deficiency existed among different maize landraces. The results based on the correlation analysis showed that the economic yield of maize landraces had relationships with their morphological and physiological characteristics under P-deficiency.     

Study on the Photosynthetic Characteristics in Spring Maize （Zea mays L.）of Different Quality Type

common maize synthetic rate（ Photosynthetic characteristics were probed by sweet maize, waxy maize, high starch maize and The results revealed that leaf area index （LAI）, chlorophyll a content, chlorophyll b content,photo-PR） showed single peak curve at the whole growth stage. The stages of peak were different according to different varieties. NEAUS4 had the lowest peak and while SIDAN 19 had the highest among all stages. Ratio of chlorophyll a to b was low at seedling stage, reached the peak atjointing stage and then declined. SIDAN 19 had the lower level at the last stages.     

Tolerance of Maize(Zea mays L. )to Chlorsulfuron

Fourteen inbreds of maize were tested for the tolerance to chlorsulfuron with the method of seedling wa- ter culter. Significant difference existed in the tolerance of different type maize when tested with 1 and 2 μg/ kg of chlorsulfuron. The tolerance in different type maize wa dent＞flint＞sugar＞midiem＞super sugar pop. The tolerance of different inbred maize was negative correlated with the concentration concentration of chorsulfuron. The tolerance of hybrids might have some relation with their parent lines because in this test the hybrids response to chlorsulfuron showed significant positive correlation with that of tits female parent which suggented some maternal in inheritance and was not controlled by nuclear. It was possible that toler- ance of maize to chlorsulfuron was cytoplasm inheritance.     

Changes of the Biomass and Acid Phosphatase Activity in Maize （Zea mays L.） Lines Under Low-P Stress

A pot culture trial was conducted to investigate the changes of the biomass and acid phosphatase （APase） activity in 10 maize lines under low-P stress. P-deficiency significantly decreased the biomass, but induced the significant enhancement of the APase activity. Since P-deficiency had smaller effects on the low-P tolerant maize lines compared with P-sensitive lines, it was demonstrated that differences of tolerance to P-deficiency existed among 10 different maize lines. In addition, the relative biomass and APase activity changed during the vegetative stage of development, and there existed a significant correlation between the biomass and APase activity under low-P stress. These results suggest that the biomass and APase activity can be regarded as indicative traits of maize lines for tolerance to low-P stress at seedling stage.     

Mapping Quantitative Trait Loci Associated with Photoperiod Sensitivity in Maize （Zea mays L.）

Photoperiod sensitivity in maize plays an essential role in utilizing tropic and sub-tropic germplasm to temperate areas. This study aims to identify and map the QTLs responsible for the characteristics measuring photoperiod sensitivity, days from planting to silking （SD）, photoperiod response coefficient of silking （PRC）, and anthesis-silking interval （ASI）. Using the population derived from Zheng 58, photoperiod-insensitive parent, and Ya 8701, photoperiod-sensitive parent, a linkage map was constructed with 93 single sequence repeat （SSR） markers. Phenotyping of 296 F2-3 families of the population in replicated-field test was conducted in both long-day （Beijing, China） and short-day （Sichuan, China） conditions. Ten QTLs were identified to be associated with the SD and ASI on chromosomes 3, 4, 6, 8, and 10 in the longday conditions, and 11 QTLs were detected to be related to the SD and ASI on chromosomes 2, 3, 4, 5, 6, 8, and 10 in the short-day conditions, respectively. A QTL associated with the PRC as a major effect in the long-day conditions located in the same position as the QTL related to the SD and ASI in the map, and was on chromosome 10 linked with marker bnlg1655. Using these QTLs in the marker-assisted selection, the photoperiod sensibility could be reduced by selection of the alleles responsible for the SD, PRC, and ASI in breeding programs.     

Analysis on Salt Tolerance of Transgenic Maize（Zea mays L. ） Crosses with BcWRKY I Gene in Seedling Stage

为了明确外源基因提高玉米耐盐性的效果,以6份转BcWRKYI基因的玉米杂交组合及其对应的6份非转基因对照组合为试材,对其发芽率、耐盐级别、株高、干重、脯氨酸含量等7个指标进行分析。结果表明：耐盐级别、发芽率、干重、叶绿素舍量和相对电导率的变化均达到显著水平,株高的变化达到极显著水平,脯氨酸含量转基因与非转基因组合间差异不显著。     

植物体内活性氧代谢及其信号传导

活性氧是植物体内一类化学性质很活泼、氧化能力很强的含氧物质的总称。它们能对机体细胞造成氧化损伤，但同时在各种防卫反应中起着积极的作用，概述了近年来植物体内活性氧代谢及其信号传导取得的研究成果。     

硫酸锌处理对玉米幼苗养分和锌累积的影响

采用0、400、800、1200和1600 mg·L^-1 5个硫酸锌浓度(以ZnSO₄·7H₂O计)的溶液浸泡玉米种子以模拟锌(Zn)污染处理,研究Zn对萌发阶段(第1、4、7、10 d)玉米幼苗胚根、胚芽生物量和养分(氮、磷和钾)累积以及胚乳干物质和养分消耗动态的影响,及其与萌发第10 d的胚根、胚芽和胚乳Zn累积的关系.结果表明,种子中钾的转化速率最快,其次为磷.低于800 mg·L^-1的处理,具有刺激玉米胚乳、胚芽和胚根中物质转化,促进幼苗氮、磷和钾养分累积和植株生长的效应;进一步升高Zn的浓度,则对胚乳、胚芽和胚根中的物质转化存在明显的抑制效应.随Zn浓度的增加,胚芽、胚根和胚乳中的Zn累积量均呈线性增高的趋势,Zn在玉米幼苗的分配量为胚乳 > 胚根 > 胚芽,胚根对Zn污染较胚芽敏感;胚乳中氮的残余量与其Zn累积量呈显著的正相关关系(P<0.05).因此,环境中的高浓度Zn,可显著增加萌发阶段的玉米胚乳Zn的累积量,降低其中的氮的转化速率,抑制玉米的生长.     

植物体内活性氧（ROS）的产生及其作用研究进展

活性氧（Reactive oxygen species,ROS）是植物体内正常代谢的信号小分子,在植物的生长发育和抗逆反应中具有重要作用。综述了植物体内ROS产生的过程、对植物蛋白的修饰及在植物体内的主要功能。     

Metabolism of Reactive Oxygen Species in the Cytoplasmic Male-Sterile Cotton Anther

Reactive oxygen species （ROS） in plant cell, including superoxide （O2^-）, hydrogen peroxide （H2O2）, and malondialdehyde （MDA）, are thought to be important inducible factors of cell apoptosis if excessively accumulated in cells. To elucidate the metabolic mechanism of ROS production and scavenging in anthers of the cytoplasmic male-sterile （CMS） cotton, CMS line, maintainer, and hybrid F1 anthers, were employed for studying the relationship between CMS and metabolism of ROS, by comparing ROS changes in the sterile and fertile anthers at different developmental stages. The results showed that during the abortion preliminary stage （sporogenous cell division stage）, anthers of CMS line had higher contents of O2^-, H2O2, and MDA than those of maintainer or hybrid F1. Simultaneously, the higher activities of superoxide dismutase （SOD）, catalase （CAT）, and peroxidase （POD） in scavenging ROS were measured in the anthers of the CMS line, indicating that an increase of ROS in anthers of abortion preliminary stage had an inducible effect on the antioxidant enzymes. But during the abortion peak of CMS anther （pollen mother cell meiosis stage）, on the one hand, contents of O2^-, H2O2, and MDA were extraordinarily high in CMS anthers, on the other hand, the activities of SOD, CAT, and POD were excessively low, which disrupted the balance between the production and elimination of ROS and led to pollen mother cells apoptosis at this stage. In the following two stages （uninucleate microspore stage and mature pollen stage）, the contents of O2^- and H2O2 in the aborted anthers were approximated to contents in the fertile anthers of the maintainer and hybrid F1. However, MDA contents were continuously raised and enzymic activities of SOD, CAT, and POD were consistently decreased in sterile anthers, which indicated that ROS still had harmful effects on the anthers after the apoptosis of the male cells. Excessive accumulation of O2^-, H2O2, and MDA and significant reduction of ROS scavengingenzyme activities were coinstantaneous with male cells apoptosis in the anthers of the cotton CMS line. But when the restorer gene was transferred into the CMS line, excessive production of ROS could be eliminated in the anthers of hybrid F1.     

锰毒对美洲商陆活性氧代谢的影响

以美洲商陆为研究材料,设置了5个锰(Mn)浓度:5(CK)、500、2000、5000、10000/μmol/L,用水培法进行试验.在处理10d和20d时,对其叶片的活性氧代谢指标进行测定.结果表明:随着锰处理时间的延长,锰胁迫使过氧化物酶(POD)和丙二醛(MDA)含量增加,表现为处理第20天时明显大于处理第10天,各时期抗氧化酶和抗氧化物的变化不均衡.锰处理第10天时,超氧化物歧化酶(SOD)和POD活性升高,过氧化氢酶(CAT)保持稳定,酶促抗氧化系统对Mn2+胁迫下活性氧具有清除作用;处理第20天时,SOD、MDA和POD活性均高于对照,CAT含量无明显变化,表明:锰处理下商陆叶片的细胞膜还没有受到明显伤害;随着锰处理浓度的增加,商陆叶片SOD和POD活性提高,保护酶活性的提高有利于活性氧自由基的清除,这可能是商陆耐锰毒的一种生理响应机制.     

植物一氧化氮及其对活性氧代谢的影响

介绍了植物一氧化氮(NO)的来源;论述了活性氧系统对NO的响应及NO对活性氧代谢调节的可能途径。     

微囊藻毒素-LR对罗非鱼肝脏活性氧自由基含量及相关抗氧化酶活性的影响

通过腹腔注射的方式研究了微囊藻毒素-LR(MC-LR)对罗非鱼肝脏活性氧自由基含量(ROS)及相关抗氧化酶,如超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性的影响。实验设计了5个剂量组(对照组、50、100、250、500μg·kg-1MC-LR),并在2、12、24、36、84h检测了ROS含量、SOD和CAT酶活性的变化。结果表明,在MC的作用下,肝脏组织能够产生大量的ROS。SOD和CAT这两种抗氧化酶在清除过量ROS的过程中发挥了不同的作用,SOD酶动态变化的过程表现为在36h突然上升后恢复的趋势,而CAT酶活性在24h和84h有两个高峰。实验结果为以抗氧化酶如SOD、CAT作为监测MC-LR引起罗非鱼毒性作用的生物标志物提供了可行性的依据,为进一步从抗氧化系统的角度研究MC对鱼类的毒性作用机制奠定了基础。     

高效生物诱导玉米单倍体及加倍方法的研究

【目的】探讨高效的玉米单倍体诱导和加倍方法。【方法】以北方春玉米区高抗茎腐病的自交系Z99和高感茎腐病的自交系R120的杂交F1代为母本,以5个诱导系(Y601~Y605)为父本,进行单倍体杂交诱导试验;以秋水仙素作为玉米单倍体人工染色体加倍药剂,采取4种处理方法(浸种法、浸芽法、滴心叶法、注射法),每种方法设置3个质量浓度梯度(0.1,0.3和0.5mg/mL)进行单倍体加倍试验。【结果】单倍体诱导试验表明,延迟授粉(长花丝≥8cm)的平均单倍体诱导率为17.4%,约为正常授粉(短花丝≤4cm)条件下的3.3倍;伏后授粉的诱导率平均为18.9%,约为伏期授粉的3.3倍。秋水仙素加倍试验中浸种法对植株伤害较严重,存活率低于50%;注射法(0.5mg/mL)和滴心叶法(0.3mg/mL)的散粉率较高(46.9%,28.3%),相应的结实率也较高(14.6%,10.9%)。【结论】花丝长短和授粉时间对玉米单倍体诱导率有重要影响,延迟授粉时间和较低的温度有利于提高单倍体诱导率;秋水仙素加倍玉米单倍体时注射法处理效果最好,滴心叶法次之。     

种子出苗率对玉米个体生长和群体产量的影响

为研究精量播种条件下玉米出苗率对产量的影响,采用‘郑单958’、‘京科968’和‘晋单73’3个玉米杂交种,在田间单粒播种条件下设置80%、85%、90%、95%和100%,5种出苗率,测定群体产量的变化。结果发现,3个品种的株高和穗位高不受出苗率影响,但果穗单穗重和穗长随出苗率的降低而增大,相反秃尖长度则减小。3个品种的产量在出苗率为100%时最高,随着出苗率的降低,产量呈现先轻微下降后显著下降的趋势,‘郑单958’和‘京科968’在出苗率低于95%时产量开始显著下降、而‘晋单73’则在低于90%时才显著下降。因此,为保障单粒播种玉米的高产稳产,‘郑单958’和‘京科968’的种子出苗率应该达到95%以上,‘晋单73’应达到90%以上。     

硅酸钠处理对厚皮甜瓜果实采后病害的控制及活性氧代谢的作用

【目的】研究硅酸钠处理对厚皮甜瓜果实采后病害的控制和活性氧代谢的作用。【方法】以‘玉金香’厚皮甜瓜为试材,用100 mmol•L-1硅酸钠常温浸泡处理10 min,处理后12 h接种粉红单端孢（Trichothecium roseum）,测定处理对果实采后病害及活性氧代谢的影响。【结果】硅酸钠处理可显著降低果实损伤接种T. roseum的病斑直径(P＜0.05)和果实的自然发病率;诱导果实过氧化氢（H2O2）的积累和超氧阴离子（ ）产生速率的提高,增加了果肉组织过氧化氢酶（catalase, CAT）的活性,抑制了前期果肉组织超氧化物歧化酶（superoxide dismutase, SOD）的活性,促进了丙二醛（malondialdehyde, MDA）的产生,降低了果肉组织细胞膜的完整率。接种后硅酸钠处理果实可进一步诱导果肉组织产生更多的H2O2和 ,提高了CAT活性,维持了SOD活性,促进果肉组织产生了较多的MDA。【结论】采后硅酸钠处理可通过调节果实活性氧的代谢来提高厚皮甜瓜果实对采后病害的抗性。