DNA CONTENT AND HETEROCHROMATIN VARIATIONS IN VARIOUS TISSUES OF PEANUT (ARACHIS HYPOGAEA)

The average 2C DNA amount for the peanut (Arachis hypogaea L.) genome is 4.21 pg, and 73% of the dormant peanut cotyledon nuclei displayed 8C DNA amounts or higher, as compared to 0 to 4% in root-shoot apices and leaf tissue. Thermal melt profiles and heterochromatin values indicated replication of the whole genome. Cotyledon nuclear DNA declined in the percent of polyploid nuclei as well as DNA amounts within ploidy classes during germination. The presence of high DNA C levels in cotyledons generated during embryogeny is interpreted to increase the protein-synthesizing capacity and subsequently supplies a ready source of nucleosides and phosphates during early embryo growth as a result of DNA degradation. However, the later DNA decline at the onset of cotyledon senescence was age related similarly to leaf senescence. The change in proportion of heterochromatin was related to the metabolic state of the tissue and not to the DNA content, as dormant and senescing nuclei contained a higher proportion of heterochromatin as compared to nuclei from metabolically active tissue such as germinating roots. The shift in heterochromatin is interpreted to be involved in gene expression.     

花生种子老化相关蛋白质的初步研究

本文以粤油 116花生(Arachis hypogaea L.)为材料,对不同处理种子的除子叶“种胚”(以下简称“种胚”)的蛋白质进行了研究.实验结果表明,当花生种子活力下降到一定程度时,其“种胚”内出现一种新蛋白质( pI6.2、MW 10 KD),随种子老化程度加深,含量逐渐增多.我们认为该蛋白质与花生种子老化存在着一定的相关关系,可作为该种子老化的标志.     

花生种子老化相关蛋白质的初步研究

本文以粤油 116花生(Arachis hypogaea L.)为材料,对不同处理种子的除子叶“种胚”(以下简称“种胚”)的蛋白质进行了研究.实验结果表明,当花生种子活力下降到一定程度时,其“种胚”内出现一种新蛋白质( pI6.2、MW 10 KD),随种子老化程度加深,含量逐渐增多.我们认为该蛋白质与花生种子老化存在着一定的相关关系,可作为该种子老化的标志.     

LOCALIZATION OF PHYTOCHROME DURING PEANUT (ARACHIS HYPOGAEA) GYNOPHORE AND OVULE DEVELOPMENT

Previous studies indirectly indicated that phytochrome plays a role in peanut (Arachis hypogaea L. cv. Virginia) gynophore elongation and in ovule and embryo development. Recent advances in the use of monoclonal antibody procedures used in this study have allowed precise localization of phytochrome in the developing peanut gynophore and ovular tissues. Peanut phytochrome from etiolated tissues was found to have a molecular weight of 124 kD as determined by immunoblotting procedures using a monoclonal antibody to pea (Pisum sativum L. cv. Alaska) phytochrome. Immunoblotting procedures revealed that no detectable phytochrome was present in the gynophore tissues or immature ovules during the elongation of the peanut gynophores. After the gynophores penetrated the soil for 8–12 d, phytochrome was detected in increasing amounts in the ovular tissues but not the gynophore tissues. Immunohistological analysis revealed that phytochrome was localized in the developing embryo and adjacent integument tissues. These findings contradict earlier reports that suggested phytochrome was initially present in the gynophore tissues after fertilization where it was believed to inhibit ovular development and stimulate gynophore elongation.     

花生种子高纯度DNA的提取（简报）

花生种子高纯度ＤＮＡ的提取（简报）王艳,何军贤,傅家瑞（中山大学生命科学学院,广州５０２７５）关键词花生;种子;ＤＮＡ;十六烷基三甲基溴化铵ＲＡＰＩＤＡＮＤＥＦＦＩＣＩＥＮＴＰＵＲＩＦＩＣＡＴＩＯＮＯＦＤＮＡＦＲＯＭＰＥＡＮＵＴ（ＡＲＡＣＨＩＳＨＹＰ...     

萌发花生种子子叶肽链内切酶的纯化和性质

萌发花生种子子叶的肽链内切酶经硫酸铵沉淀,ＳｅｐｈａｄｅｘＧ－１００凝胶层析,ＤＥＡＥ－纤维素２３阴离子交换层析和ＤＥＡＥ－ＳｅｐｈａｄｅｘＡ５０层析,得到纯化的酶,该酶有两条同工酶,分子量分别为５８和５５ＫＤ,Ｋｍ为９．９μｍｏｌ／Ｌ,是半胱氨型肽链内切酶（ＥＣ３．４．２２）,对未萌发花生种子的贮藏蛋白没有明显降解作用．     

TDZ诱导花生幼叶的不定芽和体细胞胚发生的组织学观察

花生实生苗幼叶接种于MS TDZ 0.2mg/L NAA0.4mg/L诱导培养基上经诱导培养,继而转移到无激素培养基MS可获得不定芽和体细胞胚。组织学观察表明,花生不定芽和体细胞胚均起源于愈伤组织表层,不定芽为多细胞起源,而体细胞胚起源于单个胚性原始细胞。体细胞胚的发育经历多细胞原胚、球形胚、心形胚、鱼雷胚和子叶胚等时期发育成小植株。     

甲基茉莉酸酯对花生种子萌发和贮藏物质降解的影响

甲基茉莉酸酯（Me-Ja）对花生种子萌发基本没有影响,但对下胚轴和根的生长有抑制作用,且与浓度正相关．低浓度Meja促进子叶淀粉酶活性和淀粉降解,高浓度作用相反。Me-Ja部分抑制脂肪降解、贮藏蛋白降解和内肽酶活性,明显抑制脂肪酶活性．文中还讨论了Me-a抑制种子萌发与ABA作用的异同。     

不同活力花生种子子叶内肽酶活性及花生球蛋白的降解

花生种子人工劣变后活力下降,子叶内肽酶活性降低,花生球蛋白降解速率减慢。内肽酶同工酶也发生变化,种子在劣变过程中可能诱导新内肽酶产生。     

脱落酸和抑制剂对萌发花生子叶肽链内切酶和花生球蛋白降解的影响

脱落酸（Ａｂｓｃｉｓｉｃａｃｉｄ,ＡＢＡ）抑制花生种子萌发的作用与核酸和蛋白质合成抑制剂的作用不同．ＡＢＡ（１００μｍｏｌ／Ｌ）在萌发零时施用,明显抑制肽链内切酶活性和同工酶表现以及花生球蛋白降解,萌发４８ｈ施用ＡＢＡ（１００μｍｏｌ／Ｌ）只降低肽链内切酶活性．ＡＢＡ的抑制作用不依赖于核酸和蛋白质合成．核酸合成抑制剂（３＇－脱氧腺苷,放线菌素Ｄ,５－氟尿嘧啶）和蛋白质合成抑制剂（亚胺环己酮）只能部分降低肽链内切酶活性,对肽链内切酶同工酶表现和花生球蛋白降解无明显影响．实验结果表明花生子叶肽链内酶不是在种子萌发过程中重新（ｄｅｎｏｖｏ）合成,文中讨论了肽链内切酶活性调节和花生贮藏蛋白降解的起始模式．     

The Metabolism of Proline in Higher Plants: II. L-PROLINE DEHYDROGENASE FROM COTYLEDONS OF GERMINATING PEANUT (ARACHIS HYPOGAEA L.) SEEDLINGS

The L-proline-dependent reduction of NAD⁺ has been obtainedwith a soluble enzyme extracted from acetone powders of thecotyledons of 3- to 5-day-old germinating peanut seedlings.The enzyme has been purified approximately 20-fold. NAD⁺ ismuch more effective as an electron acceptor than NADP⁺, thereaction rate with the latter being only 15 per cent that withthe former. The K_m for L-proline at pH 10.3, with NAD⁺ saturating,is 0.30 mM, and that for NAD⁺, with L-proline saturating, is0.25 mM. NADP⁺ is an excellent competitive inhibitor for NAD⁺with a K₁ of 6.2 µM. L-proline, L-proline methyl ester, and 3,4-dehydro-DL-prolineare equally effective as substrates. Thiazolidine-4-carboxylatecatalyses the reduction of NAD⁺ at 63 per cent the rate withL-proline. D-proline is not a substrate nor an inhibitor. L-prolineamide has 11 per cent the activity of L-proline and N-methyl-L-prolinehas a very slight activity. Other proline derivatives or thelower and higher homologues are completely inactive. Incubation with L-proline-¹⁴C in the presence of NAD⁺ yieldsone product which has a higher Rf than proline using butanol-aceticacid-water as the solvent in paper chromatography. Elution ofthis product and treatment with hydrogen peroxide gives severalproducts of high Rf with the same solvent mixture. None of theproducts is -aminobutyrate or glutamic acid. This eliminateseither P2C or P5C as the reaction product.     

A COMPARATIVE INVESTIGATION OF PEROXIDASES FROM GERMINATING PEANUTS (ARACHIS HYPOGAEA): ELECTROPHORESIS

Dormant seed and organs of 0-, 1-, 2-, 5-, 8-, 11-, and 14-day-old plants of Arachis hypogaea L. were homogenized in phosphate buffer and the lipid-free extracts analyzed for benzidine and pyrogallol peroxidases using starch-gel electrophoresis. On a wet weight basis, one weak band of benzidine peroxidase activity was detected in dormant cotyledons and three bands in 1-day cotyledons. In 5-day tissue, activity had increased significantly; at 14 days, the number of bands had decreased but staining intensity was maintained. In the extract from dormant axis, a single cathodic site of benzidine peroxidase activity was observed; however, on day two there was a marked increase in the number of bands and intensity of reaction in epicotyl and hypocotylradicle tissues. By day 14, the number and density of bands had decreased noticeably in the epicotyl and hypocotyl. Extracts from 14-day roots exhibited more sites of reaction and greater intensity of staining of benzidine peroxidase than at five days of growth. Localized areas of activity at Rf -0.44 and -0.52 were present in extracts of all four organs when either benzidine or pyrogallol was used as the hydrogen donor. Although marked similarity existed between banding patterns of organs, qualitative and quantitative ontogenetic differences in peroxidases were apparent.     

花生受精前后胚囊的超微结构研究

开花后１￣８ｈ,卵细胞合点端无壁,其质膜和中央细胞质膜之间有较宽间隙,两质膜均有间断处。细胞质主要分布在合点端,细胞器呈不活跃状态。一个助细胞合点端具不连续的壁,与卵细胞与中央细胞之间的“间隙”无直接联系;另一助细胞合点端仅有质膜,并通过质膜间断处与卵细胞和中央细胞之间的“间隙”相通。中央细胞珠孔端和合点端有壁内突,极核或次生核及大部分细胞质靠近卵器,内有大量淀粉粒。开花后２１ｈ,双受精已完成。合     

MICROSPOROGENESIS IN CITRUS LIMON (RUTACEAE)

Prior to meiosis tapetal cells become binucleate, and callose deposition separates spore mother cells from each other. No cytomictic channels are present during meiosis. Cytokinesis is simultaneous, by furrowing. The primexine and a rudimentary exine are laid down while the microspores are still in tetrads. After callose dissolution the released microspores gradually become vacuolate and the exine becomes more complex and massive. During the tetrad stage tapetal walls are gradually lost and orbicules are deposited outside the plasmalemma. This continues after microspore release. Later, at the vacuolate microspore stage, the tapetal cells become amoeboid and intrude among the microspores. Tapetal dissolution occurs just prior to the appearance of large amounts of starch and lipids in the microspores.