An effective in-vitro acclimatization using uniconazole treatments and ex-vitro adaptation of Phalaenopsis orchid

The in-vitro acclimatization of Phalaenopsis plantlets under photoautotrophic conditions, with 0 (control), 3.43, 6.86 and 13.72 μM uniconazole (UCZ) treatments for 30 days was investigated before the plantlets were transferred to ex-vitro environments for 14 days. The physiological and growth characters of in-vitro acclimatized, and ex-vitro adapted plantlets were measured. Chlorophyll a (Chl_a), chlorophyll b (Chl_b), total chlorophyll (TC) and total carotenoid (C_x+c) content in plantlets treated with 6.86 μM UCZ were maintained at higher levels than those in plantlets of the control, by 1.82, 1.85, 1.83 and 1.93 times, respectively, leading to enrichment of the pigments in ex-vitro conditions. The maximum quantum yield of PSII (F_v/F_m), photon yield of PSII (Φ_PSII), photochemical quenching (qP) and non-photochemical quenching (NPQ) in UCZ treated plantlets and in ex-vitro adaptation were not significantly different. Proline was accumulated in the control plantlets in both in-vitro acclimatization and ex-vitro conditions, while proline in those plantlets with UCZ treatments was maintained at a low level, which was defined by unstressed conditions. Net photosynthetic rate (P_n) in 6.86 μM UNZ treated plantlets peaked at a higher level than that of the control plantlets, both in-vitro and ex-vitro, by 3.27 and 2.93 times, respectively. In addition, proline content and P_n were inversely related in both in-vitro acclimatization and ex-vitro adaptation. The P_n in UCZ acclimatized plantlets was negatively correlated with plant dry-weight. In-vitro photoautotrophic Phalaenopsis plantlets were successfully acclimatized using a 6.86 μM UCZ treatment which caused them to adapt quickly to ex-vitro environments.     

水分胁迫下柑桔的生理变化与抗旱性的关系

本文研究了水分胁迫下柑桔叶片过氧化物酶活性、游离脯氨酸含量、叶绿素含量及水势的变化与抗旱性的关系。结果表明,遭受水分胁迫时,柑桔叶片过氧化物酶活性与游离脯氨酸含量大幅度升高、叶水势大幅度下降、叶绿素含量有较大幅度降低。抗旱性越强的种类,过氧化物酶活性与游离哺氨酸升高幅度越大、叶水势与叶绿素含量降低幅度越小。     

香稻PRO基因的克隆及表达载体的构建

利用逆转录一聚合酶链式反应(RT-PCR)得到在水稻中特异性表达的脯氨酸氧化酶(PRO)基因.DNA序列分析表明,所获得水稻的PRO cDNA的最大开放阅读框序列全长为1 428 bp,可编码476个氨基酸.该序列与NCBI网站上已发表的PRO基因100%相似.为了能进一步验证所克隆的序列是我们所需的目的基因,成功构建了PRO基因超表达载体和PRO基因干涉载体,便于导入水稻中进行基因的功能鉴定.     

水分胁迫对苹果梨叶片可溶性糖、脯氨酸含量的影响

研究了水分胁迫对苹果梨叶片可溶性糖、脯氨酸含量的影响。结果表明:水分胁迫使盆栽苹果梨叶片中的糖含量增加,增加幅度重度胁迫>中度胁迫>轻度胁迫,随着水分胁迫时间的延长,糖含量先升后降,短期恢复灌水后,均能恢复正常状态。苹果梨叶片中的脯氨酸含量对干旱的反应是很敏感的,田间苹果梨的敏感期在28d左右,盆栽幼树在11d左右,苹果梨叶片脯氨酸的含量可以看作是树体处于逆境(干旱和水涝)的一种受害反应特征,宜于作抗旱生理的响应指标,不宜作育种指标。     

母仔猪精氨酸的生理代谢与营养作用

精氨酸又称蛋白氨基酸,传统上,精氨酸不被认为是母仔猪的必需氨基酸,但是现代品种的猪生长更快,瘦肉率更高,孕育的胎儿更多,因此,对精氨酸有更高的生理需求量。大量研究表明,日粮中添加0.5%至1%精氨酸可以改善母仔猪的生产性能和繁殖性能。文章综合论述了母仔猪精氨酸的生理代谢和营养作用。     

聚乙二醇模拟水分胁迫对桑树种子萌发和生理的影响

以丰驰桑种子为材料,研究了不同浓度(0、1.0、2.5、5.0、7.5、10.0 g/L)的聚乙二醇-6 000(PEG-6 000)模拟干旱处理对桑树种子发芽和生理的影响。结果表明:用1%PEG处理后,种子的平均发芽速度、发芽率和发芽势较对照高;其他处理随胁迫强度的增加呈现明显下降趋势(均低于对照)。10%PEG处理的种子在试验开始第5天后仍未萌发。随胁迫加重脯氨酸含量先降低后升高;而可溶性蛋白和可溶性糖含量随胁迫加重呈上升趋势。     

NaCl胁迫对向日葵幼苗生长发育的影响

[目的]探讨不同浓度NaCl对向日葵幼苗生长和生理活性的影响,为盐碱地向日葵栽培提供理论依据。[方法]以向日葵矮大头567DW为材料,采用水培的方法,研究不同NaCl浓度(0、0.06、0.12、0.18、0.24mol/L)对向日葵幼苗生长状况及生理活性的影响。[结果]随着NaCl浓度的升高,向日葵幼苗的形态指标均呈下降趋势,叶片丙二醛(MDA)含量呈上升趋势,脯氨酸(Pro)含量和过氧化物酶(POD)活性呈先上升后下降趋势。在NaCl浓度为0.12mol/L时植株Pro和POD活性最高。[结论]矮大头567DW型向日葵临界耐盐浓度为0.12mol/L左右。     

Changes in Freezing Tolerance and its Relationship with the Contents of Carbohydrates and Proline in Overwintering Centipedegrass (Eremochloa ophiuroides (Munro) Hack.)

Abstract

The objective of this study was to clarify the changes in the contents of endogenous carbohydrates and proline in the stolons and leaves of centipedegrass (Eremochloa ophiuroides (Munro) Hack.), during the natural cold acclimation (hardening) and de-acclimation (dehardening) in relation to freezing tolerance in the field at the transition zone between temperate and subtropical areas in China. The contents of carbohydrates and proline, and freezing tolerance estimated by LT₅₀, which is the temperature at which 50% of the electrolytes in the organ was measured in the leachate, were determined at 10-day intervals from October 1, 2001 to April 18, 2002. It was indicated that the freezing tolerance of stolons increased (LT₅₀ of stolons decreased) quickly, as temperature dropped before winter, but that of leaves which senesced along with the drop in temperature did not. The freezing tolerance of stolons decreased gradually along with the rise in temperature above 5 °C in spring, when the overwintered plants started to grow. The contents of proline and soluble carbohydrates, including sucrose, fructose and glucose, increased as LT₅₀ decreased when temperature dropped below 5 °C before winter, and decreased as LT₅₀ increased in early spring. Correlation analysis revealed that the freezing tolerance of stolons of centipedegrass significantly and positively correlated with the contents of proline and soluble carbohydrates, and the ratio of the soluble carbohydrates to starch. Thus, the freezing tolerance of stolons, which are critical organs that determine the winter surviving ability, largely depended on the content of soluble carbohydrates and the ratio of soluble carbohydrates to starch in centipedegrass. The possible relationship between freezing tolerance and carbohydrate metabolism was also discussed.     

碱胁迫对水稻叶绿素及叶片脯氨酸和可溶性糖含量的影响

通过对沙培的4.5叶龄水稻幼苗进行5个浓度的Na₂CO₃+NaHCO₃碱胁迫处理,胁迫20d后,调查顶端叶片相对含水量、叶绿素、脯氨酸和可溶性糖含量。结果表明,随碱浓度增加叶片相对含水量先升后降;叶绿素a、b含量及叶绿素a/b为下降趋势;脯氨酸、可溶性糖含量先降后升;可溶性糖与脯氨酸含量二者具有显著相关性。碱胁迫后,对叶绿素a含量的影响较大,叶绿素b含量相对稳定;水稻通过可溶性糖含量的变化调节顶端叶片含水量及脯氨酸含量,以提高自身的抗逆性和保持新生叶片的活性。     

Mycorrhizal fungi and earthworms reduce antioxidant enzyme activities in maize and sunflower plants grown in Cd-polluted soils

Changes in plant antioxidant enzymes (AOEs) in response to cadmium (Cd) pollution are an important mechanism for plant growth and tolerance to Cd-induced stress. The main objective of this greenhouse study was to determine the combined influence of earthworm and arbuscular mycorrhiza (AM) fungal inoculation and their interactions with Cd on AOEs and proline accumulation in leaves of two major crops under Cd stress. Maize (Zea mays L.) and sunflower (Helianthus annuus L.) plants were exposed to Cd stress (10 and 20 mg kg⁻¹ soil), inoculated with either earthworm (Lumbricus rubellus L.) or AM fungi (Glomus intraradices and Glomus mosseae species) in a pot experiment for three months. Exposure to Cd decreased shoot dry weights, increased shoot Cd and P concentrations, leaf proline accumulation and the activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and polyphenol oxidase (PPO) in both mycorrhizal and non-mycorrhizal plants and both in the presence and absence of earthworms. Inoculation of both model plants with earthworms and AM fungi decreased shoot Cd concentrations and the activity of all AOEs, except PPO. Although earthworm activity enhanced the proline content of sunflower in Cd-polluted soils, the proline level of both plants remained unaffected by AM fungi. AM fungi and earthworms may decrease the activity of AOEs through a decline in shoot Cd toxicity and concentration, confirming that plant inoculation with these soil organisms improves maize and sunflower tolerance and protection against Cd toxicity. Generally, the effect of AM fungal inoculation on plant responses to Cd addition was greater than that of earthworm activity. Nonetheless, the interactive effect of AM fungus and earthworm is of minor importance for most of the plant AOEs in Cd-polluted soils.