Inferring the Gene Network Underlying the Branching of Tomato Inflorescence

The architecture of tomato inflorescence strongly affects flower production and subsequent crop yield. To understand the genetic activities involved, insight into the underlying network of genes that initiate and control the sympodial growth in the tomato is essential. In this paper, we show how the structure of this network can be derived from available data of the expressions of the involved genes. Our approach starts from employing biological expert knowledge to select the most probable gene candidates behind branching behavior. To find how these genes interact, we develop a stepwise procedure for computational inference of the network structure. Our data consists of expression levels from primary shoot meristems, measured at different developmental stages on three different genotypes of tomato. With the network inferred by our algorithm, we can explain the dynamics corresponding to all three genotypes simultaneously, despite their apparent dissimilarities. We also correctly predict the chronological order of expression peaks for the main hubs in the network. Based on the inferred network, using optimal experimental design criteria, we are able to suggest an informative set of experiments for further investigation of the mechanisms underlying branching behavior.     

Disruption of Ion Homeostasis by Verrucosin and a Related Compound

We have found that (?)-virgatusin and related compounds have antimicrobial and antifungal activity. To identify further biological activities of these compounds, we tested the activity of acridine orange efflux, which shows ionophore-like disruption of cellular ion homeostasis activity. After testing 31 compounds, we found that verrucosin and a related compound had disruption activity.     

Inflorescence Development in Chrysanthemum morifolium as a Function of Light on the Inflorescence

Covered, developing flower buds of Chrysanthemum morifoliumcv. Bright Golden Anne did not atrophy, although their dry weightwas lower than that of uncovered buds at 21, 28, 35 and 42 dafter the start of short days. This reduced dry weight was primarilydue to a reduction in the dry weight of the bracts, which arephotosynthetically active. The reduction in dry weight was notdue to a decrease in the number of bracts or florets or to alag in development of the covered buds. At 49 d the weight ofboth covered and uncovered buds was not significantly different,although the weight of the covered bracts was still reducedcompared with uncovered bracts. At 28 d uncovered buds fixedabout 40 times more ¹⁴CO₂ than covered buds. Both covered anduncovered buds had the same sink intensity and relative specificactivity, but the first bract had a greater sink intensity andrelative specific activity when covered than when uncovered,owing to photosynthesis by the bract itself. Chrysanthemum morifolium, flower development, assimilate partitioning, light, bract photosynthesis     

Invertase Activity, Soluble Carbohydrates and Inflorescence Development in the Tomato (Lycopersicon esculentum Mill.)

The concentration of reducing sugars in the developing firstinflorescence of the tomato (Lycopersicon esculentum Mill.)increased steadily between the macroscopic appearance of theflower buds and the initial stages of fruit expansion. Overthis period sucrose concentrations remained relatively constant.The rise in reducing sugar concentration was accompanied byan increase in the activity of an acid invertase. In individualflower buds invertase activity rose to a maximum shortly beforeanthesis and declined sharply as the anthers dehisced. Increased planting densities and removal of source leaves reducedthe rate of dry matter accumulation by the first inflorescenceand increased the incidence of flower bud abortion. These changeswere correlated with reductions in reducing sugar concentrations,in reducing sugar/sucrose ratios and in acid invertase levels.Removal of young leaves at the shoot apex significantly increasedthe relative growth rate of the inflorescence and led to a substantialincrease in its invertase content. These treatments had relativelylittle effect on sucrose concentration in the inflorescence. The data are consistent with the operation of an invertase-mediatedunloading mechanism for transported sucrose at sinks in theflower buds. It is suggested that the retarded development ofthe first inflorescence and the high incidence of flower budabortion observed under conditions of reduced photoassimilateavailability are causally related to the decline in invertaseproduction in the flower buds. Possible mechanisms for the regulationof invertase synthesis in the flowers are discussed. Lycopersicon esculentum Mill, tomato, inflorescence development, invertase, sink activity     

Control of Flower Number in the First Inflorescence of Tomato (Lycopersicon esculentum Mill.): The Role of Gibberellins

The number of flowers in the first inflorescence of tomato plantswas increased by low temperatures and reduced by the applicationof GA³. The effect of GA³, was greater in a low temperatureregime (12 °C minimum) than at normal temperatures (16 °Cminimum). Increases in flower number could be produced by theremoval of young developing leaves but the treatment was nolonger effective if plants wen grown at low temperatures orwere treated with GA³. Young developing leaves were shown to be sources of diffusiblegibberellin-like substances. Leaves from plants grown in a normaltemperature regime yielded greater amounts of gibberellin-likesubstances than leaves from plants grown in the low temperatureregime. It is suggested that high levels of endogenous gibberellinsact to reduce the number of flowers formed in the first inflorescence,and that leaf removal and low temperatures influence flowernumbers by lowering levels of diffusible gibberellins in theplants. Lycopersicon esculentum, tomato, flower number, gibberellins, temperature     

The Experimental Control of Inflorescence Development in Carex

In an attempt to elucidate the factors controlling the developmentof the inflorescence of Carex various substances were appliedto plants of several species during and after the transitionto the flowering phase. The main effects of the treatments onthe inflorescence were that indole-3–acetic acid and i-naphtha-leneaceticacid caused the induction of female spikelets on the sites ofpotential male flowers, 2, 3, 5-triiodobenzoic acid caused suppressionof branching and kinetin an increase in branching. All threesubstances resulted in a decrease in the flowering response,as expressed by the number of inflorescences produced. On thebasis of these results it is suggested that normal developmentof the inflorescence can be explained on a hypothesis involvingtwo substances, one probably an auxin and the other replaceablein experiments by kinetin. The possibility is considered thatthis second substance may be a kinetin-like factor producedby the roots.     

Effects of CCC on the Formation and Abortion of Flowers in the First Inflorescence of Tomato (Lycopersicon esculentum Mill.)

Treatment of tomato plants with (2-chloroethyl)trimethylammoniumchloride (CCC) reduced their growth in height and d. wt andincreased the number of flowers formed in the first inflorescence.In plants grown at a high temperature with low light, applicationof CCC reduced the incidence of flower abortion in the firstinflorescence. Effects of -cyclopropyl--(4-methoxyphenyl)--(pyrimidin-5-yl)methanol(ancymidol) were similar to those of CCC while a third growthretardant, N-dimethylaminosuccinamic acid (B-9), was effectivein reducing growth in height but was without apparent effecton flower number or flower abortion. An interaction occurred between CCC and GA₃ such that effectsof CCC on growth and flowering were reduced when GA was alsoapplied. Yields of diffusible gibberellin-like substances fromthe shoot tips were markedly reduced by treating plants withCCC but were apparently not affected by treating plants withB-9. It is suggested that effects of CCC on flowering in tomatoare mediated, in part at least, through changes in levels ofendogenous gibberellins.     

谷胱甘肽对小麦幼穗胚性愈伤组织形成以及几种相关酶活性的影响

用谷胱甘肽（GSH）处理小麦幼穗,其愈伤组织绿点率明显高于对照和BSO（buthionine sulfoximine)处理,这种效应与后期GSH诱导谷胱甘肽转移酶（GST）和醛氧化酶（ALD）活性的增加一致。     

与番茄花柄脱落相关的多聚半乳糖醛酸酶的分离纯化和特性

为弄清番茄花柄脱落相关酶—哆聚半乳糖醛酸酶（polygalacturonase,PG）的性质,采用离体培养条件下经乙烯处理的番茄花柄,分离和纯化了多聚半乳糖醛酸酶并测定其性质。结果表明：用Sephadex G-75凝胶过滤层析和CM Sepharose CL-6B阳离子交换层析方法可分离纯化得到分子量约为30．2kDa的多聚半乳糖醛酸酶,纯化倍数为30．85;纯化的PG活性最适pH值为5．0,最适反应温度为40℃;Km值为26．14mg·mL^-1;1mmol·L^-1Ca^2＋、Cu^2＋、Ba^2＋、Co^2＋和Mn^2＋可抑制PG活性,而1mmol·L^-1的Mg^2＋、K^＋、Fe^2＋、Zn^2＋、Fe^2＋促进PG活性,20mmol·L^-1的Fe^2＋和Fe^3＋促进效果尤为显著。     

Lipid Composition of Tomato Leaves as Related to Plant Cold Tolerance

We studied the effects of a low nonlethal temperature (6°C) on the content and composition of polar lipids and their fatty acids in tomato (Lycopersicon esculentum Mill., cv. Sibirskie skorospelye) leaves. We demonstrated that chilling resulted in a decrease in the content of total polar lipids per 1 mg protein. The content of lipids in chloroplast membranes (monogalactosyldiacylglycerols, digalactosyldiacylglycerols, sulfoquinovosyldiacylglycerols, and phosphatidylglycerols) changed less substantially than the content of phospholipids in other cell organelles and in the cytoplasm. Neutral lipids comprised only 1% of total lipids, and their content also decreased after chilling. The relative amounts of unsaturated and saturated fatty acids in polar lipids were practically unchanged. The conclusion was drawn that the maintenance of a high level of chloroplast membrane lipids under low temperatures could play an important role in the survival of cold-tolerant plants.     

Development of the Inflorescence in Carex

In Britain the transition from the vegetative to the floweringphase in species of Carex occurs in July or August. The younginflorescence becomes dormant in October or November and floweringoccurs the following spring. During the transition the apexenlarges both vertically and transversely, and bract primordiaare initiated low on the flanks of the meristem. Each bractprimordium subtends an axillary growth centre. Depending onthe species, the primordia which arise from the first-formedgrowth centres may develop into either lateral spikes or femaleflowers; chose formed later may develop into either male orfemale flowers. The three types of axillary structure: lateralspike, female flower, and male flower, arise from only two typesof primordia: a male flower primordium, which develops onlyas a male flower; and a ‘spikelet primordium’, whichcan develop either as a lateral spike or as a female flower,according to which of the two meristems present within it aborts.When the development of the inflorescence is interpreted interms of these two types of primordia the fundamental similaritybetween the different inflorescence types occurring in the genusbecomes evident.     

Ontogeny and Organization of the Inflorescence in Balanophora

The locus of origin of the inflorescence in the tuber of BalanophoraJ.R. & G. Forst, is predetermined. A small nest of deep-seatedhypodermal cell-layers of the tuber, encircled by compositeconducting strands, becomes meristematic and organizes a morecompact club-shaped body. Its anterior broader end is sharplydelimited from the rest of the tuber tissue. One or two celllayers of the tuber abutting its broader end break down to forma lysigenous cavity that enlarges schizogenously. These changescoincide with cessation of growth of the composite conductingstrands. The inflorescence axis redifferentiates epidermal andhypodermal tissues prior to the initiation of flowers. The procambialsystem of the inflorescence originates from (1) the base ofthe inflorescence in the tuber and (2) the shoulder regionsof the composite conducting strands; the two extensively anastomosewith each other and yet remain wholly independent of the hostvasculature. Balanophora, inflorescence, ontogeny     

The Inflorescence Papillae of the Triticeae: a New Tool for Taxonomic and Archaeological Research

The diameter of silicified inflorescence papillae and the numberof pits in the base of the papilla of 45 accessions from thegenera Hordeum, Triticum and Aegilops, were recorded using lightand scanning electron microscopy. There was a highly significantpositive correlation between pit number and papilla diameterwhen all the accessions were considered together, but therewas little correlation between these variables when each genuswas considered separately. Two wild Hordeum species were comparedwith the cultivated H. vulgare. Whilst H. murinum was very similarto H. vulgare, H. jubatum had a significantly larger numberof pits. Most, but not all, of the T. aestivum accessions investigatedhad greater papilla diameters than the H. vulgare accessions,and pit number was always greater in T. aestivum. Within thegenus Triticum pit number and papilla diameter increase as theploidy level increases from AA to AABB, and again from AABBto AABBDD. The implications of the results for taxonomic andarchaeological research are discussed.Copyright 1993, 1999 AcademicPress Hordeum, Triticum, Aegilops, inflorescence, papilla, lemma, glume, taxonomy, archaeology     

The Role of Leaves and Roots in the Control of Inflorescence Development in Carex

By using aseptic culture methods it has proved possible to studythe roles of leaves and roots in the control of inflorescenceinitiation and development in Carex. Removal of leaves upsetsinitiation and growth of the inflorescence and it is concludedthat the continued stimuli from the leaves essential for normaldevelopment are not supplied by leaves appreciably less thanhalf grown. Removal of roots or root apices upsets inflorescenceinitiation and branching. It is probable that a stimulus fromthe roots promotes initiation but is not essential, whereasa factor produced by actively growing roots is essential fornormal branching to occur. The only substance tested which couldalter the degree of branching was benzyladenine. On the evidenceavailable it is suggested that normal branching of the inflorescencemay depend on an adequate supply of cytokinin from the roots.     

番茄果实成熟过程中番茄红素含量及合成相关基因表达的分析

以2个高代自交系粉果番茄MLK1和红果番茄FL1为材料,利用实时荧光定量PCR技术及色差仪法,对果实成熟过程中4个时期的番茄红素含量分析及八氢番茄红素合成酶(Psy1和Psy2)和番茄红素环化酶(Lcy)基因的表达进行研究。结果表明,在番茄果实成熟的过程中,番茄红素的含量也逐渐增高,在完熟期达到最高,且红果中的含量高于粉果中的。在2个番茄品种果实不同部位中,Psy1、Psy2和Lcy基因在果实逐渐成熟的过程中转录水平均逐渐增加,在完熟期表达量最高,且红果FL1中的表达量高于粉果MLK1表达量,果实中Psy基因的表达量高于Lcy基因的表达量。     

The Tomato Fruit Cell Wall : II. Polyuronide Metabolism in a Nonsoftening Tomato Mutant

A nonsoftening tomato (Lycopersicon esculentum L.) variety, dg, was examined to assess the physiological basis for its inability to soften during ripening. Total uronic acid levels, 18 milligrams uronic acid/100 milligrams wall, and the extent of pectin esterification, 60 mole%, remained constant throughout fruit development in this mutant. The proportion of uronic acid susceptible to polygalacturonase in vitro also remained constant. Pretreatment of heat-inactivated dg fruit cell walls with tomato pectinmethylesterase enhances polygalacturonase susceptibility at all ripening stages. Pectinesterase activity of cell wall protein extracts from red ripe dg fruit was half that in extracts from analogous tissue of VF145B. Polygalacturonase activities of cell wall extracts, however, were similar in both varieties. Diffusion of uronic acid from tissue discs of both varieties increased beginning at the turning stage to a maximum of 2.0 milligrams uronic acid released/gram fresh weight at the ripe stage. The increased quantity of hydrolytic products released during ripening suggests the presence of in situ polygalacturonase activity. Low speed centrifugation was employed to induce efflux of uronide components from the cell wall tree space. In normal fruit, at the turning stage, 2.1 micrograms uronic acid/gram fresh weight was present in the eluant after 1 hour, and this value increased to a maximum of 8.2 micrograms uronic acid/gram fresh weight at the red ripe stage. However, centrifuge-aided extraction of hydrolytic products failed to provide evidence for in situ polygalacturonase activity in dg fruit. We conclude that pectinesterase and polygalacturonase enzymes are not active in situ during the ripening of dg fruit. This could account for the maintenance of firmness in ripe fruit tissue.     

光质对黄瓜及番茄愈伤组织培养中分化和有关酶的影响

黄瓜及番茄愈伤组织培养过程中的分化和生理生化过程明显地受到光质处理的影响,它们的过氧化物酶(POD)和苯丙氨酸解氨酶(PAL)的活性变化与组织及器官的分化都有一定的相关性。黄瓜愈伤组织培养中POD及PAL的第3个活性峰的出现与芽的分化一致,红光与绿光抑制黄瓜愈伤组织培养中芽的分化,不出现第3个活性峰。两种材料培养后培养物的生物重量在不同光质下也有明显差异,但含水率之间无差异。