The Effect of Fusicoccin and Monovalent Cations on the Viability of Wheat Seeds

Fusicoccin (FC), K⁺ and Na⁺ restore the viability of aged wheatseeds and isolated wheat embryos. We studied the effect of FCand K⁺ on the evolution of the proton extrusion activity andnet K⁺ uptake during the early phases of germination of wheatembryos isolated from unaged and aged seeds. Our data show thatin this material, germination is also characterized by the activationof the proton-extruding activity and by the leakage and subsequentre-absorption of K⁺. The percentage of germination appearedto be correlated with the amount of proton extrusion and K⁺net uptake. In aged embryos the positive effects of FC and K⁺on germination were correlated with a marked increase in bothproton extrusion and K⁺ net uptake. These findings suggest that:(a) in wheat seeds, germination is also correlated to the activationof a mechanism linked to H⁺/K⁺ exchange; (b) the damage of thismechanism is, under our conditions, responsible for the lossof viability.     

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.     

Natural Ageing: Poly(A) Polymerase in Germinating Embryos of Triticum durum Wheat

The viability of seeds is associated with ageing and storageconditions. A loss of viability is accompanied by slow germination,reduced growth, and a decline in protein and poly(A)⁺RNA synthesis.This paper reports on the activity of poly(A) polymerase indry and germinating embryos of Triticum durum Desf. cv. Cappellicaryopses of different ages and viability. The enzyme was presentas a single form during ageing and germination. The poly(A)polymerase was active at decreasing levels in all aged dry embryos,in parallel with loss of viability. Its activity strongly increasedduring the germination only in viable embryos. The observedincrease was due to de novo synthesis of the enzyme. Poly(A)polymerase synthesis was low during germination of less viableembryos and absent in older ones. Reduced poly(A) polymeraseactivity in dry or germinated wheat embryos may cause a shorteningof poly(A) chains in vitro and a decline in poly(A)⁺RNA synthesis.Copyright1995, 1999 Academic Press Triticum durum Desf. cv. Cappelli, wheat, embryo, natural ageing, poly(A) polymerase     

Ageing of isolated embryos and endosperms of durum wheat: An analysis of chromosome damage

Embryos (EM) and endosperms (END) were isolated from durum wheat seeds and aged separately for 3 years. Analysis of chromosome damage was carried out on root tip meristems of transplants in which aged (a) embryos and/or endosperms were used. The aim of the experiments was to investigate the ageing process when embryos and endosperms age separately and to evaluate the possible influence of the endosperm during storage of the seed.The results obtained indicate that (i) both aged embryo and endosperm produce mutagenic substances capable of inducing nuclear damage in the radicle meristem and (ii) age-induced damage in the embryo is not the consequence of endosperm ageing. The relationships between chromosome damage produced by aged embryos and endosperms in the transplants are discussed.     

A Comparison of Changes in the Germination Responses and Phospholipid Composition of Naturally and Artificially Aged Tomato Seeds

The changes in germinability and phospholipid content of naturallyand artificially aged tomato seeds, variety Kingley Cross, werecompared. Subsequent low temperature pre-sowing treatment (LTPST)was unable to prevent decreases in the germination capacityof aged samples, but significantly improved germination rates.However, in contrast to previous studies on artificial ageingusing the variety Moneymaker, losses of total phospholipid werenot always well correlated with decreased germinability. Totalphospholipid levels in naturally aged seeds were largely unaffectedby pre-sowing treatment, but the proportion of phosphatidylcholinewas greatly increased. These results strongly suggest that lossesof phospholipid are coincidental rather than causative eventsin the loss of seed viability during ageing, and that the patternof changes depends on the type of ageing experienced by theseeds. Controlled deterioration, seed ageing, tomato seeds, seed treatment, phospholipids     

小麦内生细菌及其对根茎部主要病原真菌的抑制作用

对小麦植株不同生育期、不同器官的内生细菌进行了分离和数量变化分析.结果表明,根、茎、叶及未成熟籽粒等器官中存在大量的内生细菌,鲜组织中平均约含内生细菌5.0×10⁵ CFU·g^-1,其中根系中内生细菌数量达7.8×10⁵ CFU·g^-1,而茎秆、叶片和未成熟籽粒中内生细菌数量分别为4.8×10⁵、3.2×10⁵和2.8×10⁵ CFU·g^-1.内生细菌数量在不同生育期也存在差异,幼苗期平均约为3.1×10⁵ CFU·g^-1、拔节期和灌浆期分别为5.7×10⁵和7.0×10⁵ CFU·g^-1.不同小麦田块之间存在明显差异,长武县一田块植物鲜组织中内生细菌的数量为6.1×10⁵ CFU·g^-1,而大荔县一田块约为3.9×10⁵ CFU·g^-1.试验结果发现,对小麦全蚀病菌具有拮抗作用的内生细菌有51株、对小麦纹枯病菌具有抑制作用的内生细菌有45株.用平板对峙法测定,有71株对两种病原真菌均有拮抗作用,对小麦全蚀病菌抑菌圈直径大于10 mm的有23株,其中来源于根系、茎秆、叶片和籽粒的分别为6株、7株、9株和1株;对小麦纹枯病菌抑菌圈超过10 mm的有20株,其中来源于根系、茎秆、叶片和籽粒的分别为7株、5株、7株和1株,说明从小麦叶片诱捕分离的内生细菌中,对小麦全蚀病菌和纹枯病菌抑菌作用较强的分离株比率最高,其次为茎秆,而根部和未成熟籽粒中比例明显较低.     

Study on the mechanism of cerium nitrate effects on germination of aged rice seed

Attempts were made to promote germination of naturally and artificially aged rice seeds by treating them with cerium nitrate. The germination rate, germination index, and vigor index of aged rice seed were significantly increased by cerium. It was because the treatments of aged rice seed with cerium nitrate enhanced respiratory rate and activities of superoxide dismutase, catalase, and peroxidase, and decreased superoxide O₂ ⁻ and malondialdehyde contents that plasma membrane permeability was reduced. It was suggested that cerium be used for the seed treatment before sowing.     

Factors Affecting the Biosynthesis of Abscisic Acid

Incorporation of labelled mevalonate into abscisic acid (ABA)has been demonstrated in the cotyledons of mature avocado seeds,embryos and endosperms of developing wheat seeds, and avocadostems. The increase in ABA concentration on wilting parallelsthe increased incorporation of [2^–14C)mevalonate intoABA in avocado leaves and stems, suggesting that the increasein ABA content occurs by synthesis rather than by release froma stored precursor. Incorporation of [2^–14C]mevalonateby avocado mesocarp segments is unaffected by an 18 per centwater loss. The ABA content of roots was hardly affected bya 30 per cent water loss, indicating that the wilt-activatedmechanism is not fully operative in these tissues. Submerged Ceratophyllum plants and submerged parts of Callitricheshoots show a twofold increase in ABA content on wilting whereasthe aerial rosettes of the latter plant show a sixfold increase.This suggests that the occurrence of the wilt-induced mechanismis affected by previous growth conditions as well as by themorphology of the tissue.     

Comparative studies on the changes of total soluble proteins and protease activity in Georgian commercial peanuts contaminated by Aspergillus flavus

The presence of Aspergillus species is an indicator of storage conditions, which also suggests the possibility of several biochemical changes in grains. A comparative change in total soluble proteins and protease activity was determined in commercial peanut seeds collected from Georgia State. Protein contents of healthy peanuts, naturally contaminated peanuts and then artificially inoculated peanut seeds with A. flavus were estimated by Bradford method, and protease activity was also determined by using the Protease Detection Kits. Protein contents and the protease activity of the peanuts varied from sample to sample. The soluble protein content of seeds was significantly higher in healthy peanuts than in artificially inoculated or naturally infected peanuts with A. flavus. Protease activity was found to be higher in artificially inoculated seeds than in either naturally infected or healthy peanuts. Level of soluble proteins in buffer extracts of contaminated seeds decreased with incubation time, and protease activity increased with incubation time. These changes may be attributed to host response due to infection, contribution by A. flavus or due to biochemical alterations that occur naturally during the transition from endosperm to seedling during incubation period.     

Proteolytic Activities in x Haynaldoticum sardoum Seeds of Different Ages

Carboxypeptidase, aminopeptidase and proteinase activities weremeasured in endosperms from dry and germinating x Haynaldoticumsardoum naturally aged seeds. Carboxypeptidase activity, presentin dry seeds, decreased slightly during germination and remainednearly unchanged during the storage period. Aminopeptidase activityincreased during germination in younger seeds, but decreasedin non-viable seeds. Proteinase activity was absent in dry seeds,increased during germination in younger seeds and disappearedin the older ones. Proteinase activity was not recovered in old endosperms followingtransplantation of young embryos, and was recovered only toa very small extent in young endosperms following transplantationof old embryos. Young endosperms onto which young embryos hadbeen transplanted gave maximum recovery of enzyme activity,although this was lower than in young intact seeds. These results suggest that the reduced or delayed availabilityof nutrients to the embryo axis is not the only factor causingthe failure of seeds to germinate, the ageing process beinga progressive phenomenon affecting both embryo and endosperm. x Haynaldoticum sardoum, Denti de cani, seed ageing, proteolytic activities, embryo-transplantation     

Studies into Causes of Non-germination of Aged Wheat Seeds

Excised embryos of aged non-germinating wheat seeds, when placedon sucrose/glucose germinated well and grew into normal plantlets,while on agar alone they remained ungerminated as in the intactseed. From the results of amylase assays in seeds of differentages it appears that failure of amylolytic activity in agedseeds could be a cause of unavailability of utilizable subtrateto the embryonic axis of aged seeds. This would bring abouta limitation in the capacity of germination and growth of theembryonic axis even before the embryo becomes non-viable. Wheat (Triticum aestimon L. cv. Sonalilca), embryo, germination, sucrose, amylase     

Changes in nucleic acids, protein-nitrogen and amino-nitrogen of excised winter wheat embryos during vernalization

Embryos excised from winter wheat grains were vernalized for10–50 days with or without sugar (sucrose). Determinationswere made of fresh weight, protein-nitrogen, amino-nitrogen,RNA and DNA. There was no change in the contents of RNA of wheatembryos during the vernalization. The incorporation of ³²P intonucleic acid in wheat embryos during vernalization in the presenceof sugar was much higher than that of embryos vernalized withoutsugar. From these results we assumed that RNA turnover occurredduring the vernalization. There was no significant differencein the nucleotide composition of RNA extracted between the vernalizedand unvernalized embryos. The RNA of wheat embryos was separatedinto two fractions. Proportions of these two RNA fractions variedin the course of cold treatment, and similar changes were foundin developing wheat leaves. (Received July 25, 1974; )     

Ageing and Osmotic Priming in Wheat Seeds: Effects Upon Certain Components of Seed Quality

Deteriorated wheat seed lots were osmotically primed and surface-dried,dried-back, then aged for two more weeks Osmotic priming didnot affect the final germination in any of the aged seed lots,but mean germination time was decreased The response of unagedseed lot to treatments was studied in the following the timecourses of germination, as well as L-[4, 5-²H]leucine and [6-³H]thymidineincorporation (as a measure of protein and DNA synthesis, respectively)into dissected embryos during the early hours of germinationIt was found that the variation in mean germination time andthe rate of synthetic reactions were related The greatest improvementin the components of seed lot quality was achieved after primingand surface drying The beneficial effects of priming were apparenteven after dehydration followed by two further weeks of ageingCumulative correlations between mean germination time and variousbiochemical tests in variously treated aged seed lots were highlysignificant The physiological processes involved in deteriorationand recovery and the potential application of biochemical testsin detecting vigour changes are discussed Triticum durum, seed, ageing, osmotic priming, mean germination time, protein DNA synthesis     

The Long Term Metabolism of ({+/-})-(2-14C)Abscisic Acid by Apple Seeds

Apple seeds soaked in a solution of [±]-[2-¹⁴C]abscisicacid for up to 70 d formed phaseate and the epimeric dihydrophaseatesand all four acids were converted into alkali-hydrolysable conjugates.This metabolism occurred in the husks and in the embryos. Bothparts of untreated control seeds contained the four acids andtheir conjugates. In addition to these characterized metabolites,a number of other, labelled, acidic products were isolated fromthe seeds. ¹⁴CO₂ was evolved from unsterilized seeds but notfrom surface-sterilized ones. Bacterial cultures isolated fromsoil and rotting fruit metabolized [¹⁴C]ABA to a range of compounds,but not to phaseic or the dihydro-phaseic acids. A new, acidicconjugate of ABA is described.     

He-Ne激光对增强UV-B辐射小麦幼苗多胺氧化酶和过氧化物酶活性的研究

采用He-Ne激光辐照对增强UV-B辐射后小麦幼苗的损伤修复作用进行了研究。小麦种子在盛有湿滤纸的培养皿内25℃下进行萌发。萌发后小麦幼苗在经10.08 kJ·m^-2·d^-1的增强UV-B辐射,然后再用5 mW·mm^-2的He-Ne激光进行辐照。通过小麦幼苗叶片游离脯氨酸含量、多胺氧化酶和过氧化物酶的活性变化,测定了He-Ne激光对小麦UV-B损伤的修复情况。结果表明,游离脯氨酸、多胺氧化酶、过氧化物酶的变化同小麦幼苗损伤的修复的能力相关联。He-Ne激光辐照可使由增强UV-B辐射后诱导叶片升高的游离脯氨酸含量降低。增强UV-B辐射对多胺氧化酶（PAO）活性和过氧化物酶（POD）活性呈促进的作用。辐射6 d后PAO和POD总的活性呈正相关性,PAO和POD活性都呈现B组最高,L组最低,且差异显著。显示He-Ne激光对两种酶由于增强UV-B辐照造成的伤害有一定的修复。     

In vitro germination and induction of direct somatic embryogenesis in 'Bottle Palm' [Hyophorbe lagenicaulis (L. Bailey) H.E. Moore], a critically endangered Mauritian palm

Hyophorbe lagenicaulis is a critically endangered palm of Mauritius. Zygotic embryos were isolated from seeds and germinated in vitro on MS salts and vitamins containing activated charcoal. When seedlings were pre-treated in vitro for 2 weeks in liquid medium containing 0.05 mg l^-1 paclobutrazol, 80% survived the transfer to soil. Three-week-old seedlings were sectioned longitudinally and partially embedded in medium that contained MS salts and vitamins, 30 g l^-1sucrose and 3 mg l^-1 2,4-dichlorophenoxyacetic acid. Somatic embryos were formed, in profusion, directly (without callus) from the haustorium, plumule and radicle. Direct regeneration is important for the conservation of endangered species, as fewer somaclonal variants are likely to arise than from indirect regeneration. When the haustorium, plumule and radicle of the longitudinally sectioned seedlings were separated, they formed more callus but fewer embryos. Plantlets derived from somatic embryos have not yet been successfully established in soil.     

Changes in hybridizable RNA in winter wheat embryos during germination and vernalization

DNA-RNA hybridization-competition experiments were performedto analyze RNA heterogeneity in wheat embryos during germinationand vernalization. A significant difference was found betweenRNA populations of 24-hr and 3-day germinated embryos, whileminor differences were detected between 3- and 5-day germinatedembryo RNAs and between 20- and 40-day cold-treated embryo RNAs.RNA populations in 30-day cold-treated embryos were significantlydifferent from those in 50-day ones. The RNA species presentin 50-day cold-treated embryos were not similar to those in3- and 5-day germinated embryos. A great portion of the RNAspecies in 3-day germinated embryos was found in 30-day cold-treatedembryos. These results suggested that some new RNA species aresynthesized in wheat embryos during 30 to 50 days of cold treatment. ¹ Present address: Department of Biochemistry, Faculty of PharmaceuticalSciences, Higashi Nippon Gakuen University, Ishikari-Tobetsu,Hokkaido 061–02, Japan. (Received February 21, 1977; )     

Seed germination and growth in Triticum I. Biological activity of extracts from T. durum endosperms

The nature of germination inhibitors in seeds of Triticum durumwas investigated. From a methanol extract of isolated endospermsof "Cappelli" wheat, two fractionations were carried out andfractions were tested for their influence on mitotic processesand growth of Triticum "Cappelli" plantlets. One of the sub-fractionsdepressed root growth, caused accumulation of metaphases, andinduced chromosome aberrations. The biological activity of thissub-fraction closely resembles that of the germinations inhibitorsof wheat seeds. ¹ This work was supported by a grant from the Consiglio Nazionaledelle Ricerche. (Received October 19, 1971; )     

Polyamine Content Related to Seed Storage Performance in Zea mays

As part of a search for biochemical indicators of seed withgood survival characteristics during storage, polyamine (PA)levels were measured in embryos for Zea mays seeds. PA levelswere determined in individual embryos of Mean Generation Analysis(MGA) of crosses between lines which show good (C²) and poor(C⁶) storage characteristics. A correlation was found betweenhigher PA contents (putrescine and spermidine) and superiorsurvival characteristics within the populations that were analysedby MGA. Titres of putrescine (PUT) and spermidine (SPD) showedthat three-quarters of the F² resembled the C² parent and aquarter resembled the C⁶ parent. Furthermore, the backcrossC⁶F¹ showed that half of the embryos had PUT levels above theparental C⁶ line. A maternal inheritance effect was not observed.Neither spermine nor cadaverine content was correlated withthe survival inheritance pattern. Given the survival kineticsobtained, it is suggested that both the PA titres and the seedsurvival characteristics are determined by nuclear dominantfactors. Key words: Polyamines, Zea mays, seeds     

Differential Changes in Levels of mRNAs during Maturation of Wheat Seeds That Are Susceptible and Resistant to Preharvest-Sprouting

Seed dormancy is strongly related to the physiological conditions,especially as they relate to responsiveness to ABA, of embryocells during maturation of seeds. In this study, seeds of Triticumaestivum L. cv. Chihoku, which showed nondormancy at harvest,and line Kitakei-l354 (referred to as Kitakei), which showedpost-harvest dormancy, were collected 30 days after anthesis(DPA 30) and at the mature stage (DPA 60). Poly(A)⁺RNA was extractedfrom the embryos of the seeds and translated in a wheat germsystem. The majority of products of translation from the twogenotypes migrated to the same positions in two-dimensionalgels. Levels of six (for polypeptides h, i, k, m, n, and o)out of 14 Chihoku-specific mRNAs decreased dramatically duringseed maturation, concurrently with the loss of dormancy. Bycontrast, levels of 3 (for polypeptides c, e and f) out of 6Kitakei specific mRNAs were maintained during maturation andduring a 48-h imbibition of the dormant seeds but decreasedat germination. Polypeptides n of Chihoku and e of Kitakei hadthe same molecular size and slightly different pI values. Thesetwo polypeptides may be encoded by the same gene and may playsome role in the maintenance of seed dormancy. Levels of mRNAsfor 10 polypeptides, found in both Chihoku and Kitakei embryosat DPA 30, changed to different extents during maturation. Outof the 10 mRNAs, the relative abundance of 4 mRNAs of Kitakeidid not change dramatically during seed maturation, while inChihoku these mRNAs decreased in level or disappeared duringthe same maturation period. In addition, levels of 2 of these4 mRNAs did not decrease significantly during imbibition ofthe dormant Kitakei seeds but disappeared upon treatment forbreaking of dormancy. The maintenance of these mRNAs in thedormant seeds during maturation and imbibition suggests thatthe respective gene products are involved in the maintenanceof dormancy in wheat seeds. (Received December 5, 1991; Accepted April 1, 1992)