Young Spikes Research Articles

Molecular cloning of three homoeologous cDNAs encoding orthologs of the maize KNOTTED1 homeobox protein from young spikes of hexaploid wheat

The plant knotted1 ( kn1)-like homeobox genes are known to play important roles in the maintenance of shoot apical meristem (SAM), determination of cell fate and differentiation of vegetative tissues. To study structural diversity of the three homoeologous loci encoding a KN1-like homeobox protein in the hexaploid wheat genome, we isolated clones from a cDNA library of young spikes of Japanese common wheat cultivar ‘Norin 26’. Three different but highly homoeologous cDNAs were isolated and their sequences were determined. The mean homology of the deduced amino acid sequences was 96% as compared to the barley ortholog KNOX3. The wheat kn1-like homeobox proteins named WKNOX1 are encoded by a single set of homoeologous genes on the homoeologous group 4 chromosomes in the three component genomes of common wheat, i.e. 4A, 4B and 4D. The nucleotide sequence data and the Southern blot pattern suggested that the three homoeologous loci of wknox1 genes are highly conserved through polyploid evolution of wheat. They were expressed in SAM-containing shoots and young spikes but not in developed leaves, glumes and lemmas and callus tissues. The ectopic expression of the wknox1 was observed in lemma of wheat Hooded ( Hd) mutants. The result suggested that the Hd gene is a dominant allele of the wknox1 locus on chromosome 4A.

Direct isolation of differentially expressed genes from a specific chromosome region of common wheat: application of the amplified fragment length polymorphism-based mRNA fingerprinting (AMF) method in combination with a deletion line of wheat

The amplified restriction fragment length polymorphism (AFLP)-based mRNA fingerprinting (AMF) method makes it possible systematically and conveniently to identify differentially expressed cDNAs with high reproducibility. We have applied the AMF method to the cloning of the Q gene of common wheat, which is located on the long arm of chromosome 5A and pleiotropically controls the spike morphology and the threshing character of seeds. Using the AMF method, we compared the fingerprints of mRNA samples extracted from the young spikes of Triticum aestivum cv. Chinese Spring (CS) carrying the Q gene to those of a chromosome deletion line of CS, namely, q5, which lacks 15% of 5AL including the Q gene. Approximately 12,200 fragments were produced after PCR with 256 primer combinations. Of these, 92 fragments were differentially expressed between CS and q5. Northern and Southern analyses showed that 16 fragments gave specific or relatively stronger transcript signals in CS, and these clones were present in single copy or in low copy numbers in the wheat genome. Four clones were genetically mapped to the region deleted in q5. Subsequently, one clone, pTaQ22, was mapped at the same locus as the Q gene, indicating that pTaQ22 corresponds to the Q gene or is tightly linked to it. DNA sequence data showed that pTaQ22 had no homology to any known genes, thus suggesting a novel function for this gene in flower morphogenesis. This AMF method might provide a straightforward method for isolating genes in the hexaploid background of common wheat.

Cloning of cDNAs specifically expressed in wheat spikelets at the heading stage, as identified by the simple differential display method

Wheat cDNAs expressed in the spikelets at the heading stage were isolated according to the PCR-mediated simple differential display method. The wheat spikelets at the heading stage contain a pair of glumes, a lemma, a palea, a pair of lodicules, three stamens and a pistil. Anthers harbor bi-, and tri-nucleate pollen cells. Out of 76 RAPD primers examined, 13 primers gave 29 spikelet-specific bands. After cloning of these bands, 34 independent cDNAs were recovered by the DNA sequencing of these clones. A homology search of these cDNAs showed the existence of genes homologous to meristem identity genes such as LEAFY and APETALA1 in Arabidopsis as well as other flower organ specific genes encoding UFO, pollen-, anther-, inflorescence-, and immature flower-specific proteins. Additionally, novel genes in the plants were obtained. Northern blot analysis of these clones revealed that rare as well as abundant mRNAs were also clonable, and 14 cDNAs were specifically or highly expressed in the flower organs rather than in the other tissues including young spikes. Fourteen cDNAs were classified into six groups, based on the hybridization patterns. Furthermore, the six groups were divided into two major groups: (1) cDNAs specifically expressed in certain tissues of the wheat flower (lodicule, stamen, pistil and lemma/palea-pistil), and (2) cDNAs continuously transcribed in the flower organs. These genes might play roles in gamete formation and/or maintain the activity of flower organs at the heading stage.

Post-Emergence Control of Broomrape with Natural Plant Oils

ABSTRACT The effect of natural oils on broomrape (Orobanche cernua Loefl.) was assessed in a naturally infested tobacco (Nicotiana tabacum L.) field at the Agricultural Research Station, Nipani, India, during 1994–95. Natural oils which are available at low cost and biodegradable differed in their ability to kill the young broom-rape spikes. Neem (Azadirachta indica Juss.), coconut (Cocas nucifera L.), and sunflower (Helianthus annuus L.) oils showed knock-down effects on the bud part of the parasite within 2–3 days, castor (Ricinus communis L.) and niger (Guizotia abyssinica (L. fil.) Cass.) oils killed the buds within 3–4 days. Mustard (Brassica juncea (L.) Czernjaew) oil took 5 days to kill the bud. Coconut and sunflower oils also killed the broomrape stem more quickly than niger and castor oils. Neem oil and mustard oil did not kill the stem part of the parasite. These findings give new information on relative efficiency of different plant oils in controlling broomrape. None of the oils was phytotoxic to tobacco. After optimization of application techniques the use of such oils in practice will be cheap, environmentally safe and effective.

Wheat MADS box genes, a multigene family dispersed throughout the genome.

Polymerase chain reaction (PCR) with degenerate primers was utilized for partial cloning of the MADS box gene family from wheat (Triticum aestivum L.). PCR products corresponding to a part of the MADS box region were cloned and sequenced. Eleven individual clones sequenced were classified into seven types on the basis of the nucleotide sequence and five types on the deduced amino acid sequence, which included two wheat-specific MADS box protein sequences. RT-PCR analysis with degenerate primers revealed preferential expression of the MADS box genes in young spikes. Furthermore, genomic Southern blot analysis with degenerate PCR products as probes indicated that wheat MADS box genes constitute a multigene family and are dispersed throughout the genome.

Studies on the relationship between air temperature and the differentiation of young spikes of winter wheat in Beijing district

In these studies the optimum temperature indices for spikelet differentiation were found. The critical period determining the number of spikelets on a spike lies between the single ridge stage and the stage of glume differentiation. During this period a daily temperature below 7.5°C is favourable for differentiation of further spikelets. The processes of differentiation of wheat spikes need certain accumulated temperatures for a mean daily temperature above 0°C. The relationship between the rate of spikelet differentiation and temperature during the differentiation period, and the of these periods are discussed. According to the effect of climate in early spring on the number of differentiated spikelets of winter wheat, three climatic types in early spring are suggested.

Identification of cytokinins in young wheat spikes (Triticum aestivum cv. Chinese spring)

Cytokinins in young wheat (Triticum aestivum cv. Chinese spring) spikes (2–15 mm) were isolated by immunoaffinity chromatography. High-performance liquid chromatography-radioimmunoassay and gas chromatography-mass spectrometry indicated that major cytokinins present weretrans-zeatin, ribosyl-trans-zeatin, ribosyldihydrozeatintrans-zeatin-9-glucoside, and the glucosides oftrans-zeatin, ribosyl-trans-zeatin, andtrans-zeatin-9-glucoside. Dihydrozeatin,iso-pentenyladenosine, andiso-pentenyladenine were also present but at lower concentrations.

Growth and grain yield of wheat in relation to differences in soil groups. I. Growth and grain yield of wheat varieties under the same fertilizer conditions.

The differences in growth and grain yield of seven wheat varieties cultivated in soils belonging to four different groups were examined under the same fertilizer conditions during two growing seasons, 1982-84. Plant growth was most vigorous in the Gray Lowland Soils (GLS). In the Red Soils (RS) tillering stopped and the leaf color became pale in late January. In the Thick High-humic Andosols (THA) and the Light-colored Andosols (LCA), tillering and leaf emergence rates were lower than in the other soils from the start of the tillering stage. The young spike and culm elongation occurred earlier in RS and later in THA and LCA. Grain yield was 649 g/m2 in GLS and 440-500 g/m2 in the other soils. Lower yield in RS was due to the decline in the spike number and grain weight per spike, whereas in THA and LCA it was due to the decrease in the spike number. These differences in the growth and grain yield of wheat in each soil were mainly associated with the soil fertility and soil temperature patterns. The varieties with the greatest yield was differed with each soil. In the most fertile soil, GLS, the yield of Asakazekomugi was the highest, because of the higher percentage of productive tillers (ca. 50%), large spike number, and less lodging which reduced the loss of grain weight per spike. In THA and LCA, the yield of Norin 64 was the highest, because of the vigorous tillering activity and the larger spike number. In RS the yield difference among varieties was not significant.

High capacity of plant regeneration from callus of interspecific hybrids with cultivated barley (Hordeum vulgare L.)

Callus was induced from hybrids between cultivated barley (Hordeum vulgare L. ssp. vulgare) and ten species of wild barley (Hordeum L.) as well as from one backcross line ((H. lechleri x H. vulgare) x H. vulgare). Successful callus induction and regeneration of plants were achieved from explants of young spikes on the barley medium J 25–8. The capacity for plant regeneration was dependent on the wild parental species. In particular, combinations with four related wild species, viz. H. jubatum, H. roshevitzii, H. lechleri, and H. procerum, regenerated high numbers of plants from calli.

Development of the Young Wheat Spike: A Sem Study of Chinese Spring Wheat

Development of the Young Wheat Spike: A Sem Study of Chinese Spring Wheat

Studies on Abnormal Hypertrophy of Tapetum caused by Auxins in Rice Plants, especially in Relation to that caused by Low Temperature

It is well known phenomenon that abnormal hypertrophy of tapetum takes place in rice plants encountered with an unfavourable low temperature. In a previous paper we have discribed the phenomenon of abnormal hypertrophy of tapetum might be an incidence controlled by the level of endogenous auxin during the anther development. This experiment was carried out with the purpose to prove if exogenously supplied auxins can induce the same abnomral hypertrophy of tapetum as that caused by the low temperature. Naphthaleneacetic acid (NAA) and 2, 4-dichlorophenoxyacetic acid (2, 4-D) were used at concentrations of 0.1, 1.0 and 10.0 ppm. The young spikes at the period of first and second constructions of micrspores were floated on the solution of chemicals for 24 hr at room temperature. Then the anthers were fixed in FAA and prepared for histological observations by means of the usual paraffin method sectioning about 10μ in thickness. Various types of tapetal abnormalities as shown in figs. 2∼17 were observed in the anthers treated with auxins, especially in the plots of the higher concentrations. Thus it became clear that the auxins used obviously induce or promote the same tapetal hypertrophy as that caused by the low temperature. These results seem to support the concept previously reported by the writers that appearance of the tapetal hypertrophy under the low temperature might have a close relationship with the endogenous level of auxin during the anther development. The interaction between auxins and RNA in connection with the abnormal development of tapetum was discussed quoting Dr. Shibuya's experimental result that the tapetal abnormality was induced by application with uridine-monophosphate or triphosphate plus glucose-1-phosphate.

THE EFFECT OF 4,6‐DINITRO‐O‐CRESOL* (DNOC) ON GROWTH, DEVELOPMENT AND YIELD OF WINTER RYE (SECALE CEREALE L.)

Summary. The spraying with DNOC as a herbicide in a young crop of winter rye results in an increased grain yield, even in weed‐free trials. In order to trace the sequence of reactions by which treatment in winter affects the yield next summer, growth, development and yield of treated and untreated plants were examined in a single weed‐free experiment which included the study of several seed rates.As a result of the DNOC treatment, vegetative growth was retarded at first, but later the treated plants recovered and surpassed the control plants in fresh and dry weight. Since their dry matter percentage was somewhat lower and their nitrogen content a little higher, the crop appeared both more vigorous and more youthful. Leaf blade area and chlorophyll content of leaves and culms were increased and chlorophyll breakdown at ripening was delayed.No effect could be observed on the rate of development of the young spike, but heading, flowering and ripening were retarded.Yield increase on the DNOC‐treated plots was 10% on an average. The analysis reveals that on these plots 3% more culms were formed, each of which bore 5% more kernels; the average kernel weight was unaffected. The increase in ear density can be ascribed to the more luxuriant vegetative growth, while the kernel weight per car is correlated with the nitrogen content of the culm.It is concluded that the yield increase is due to a stronger vegetative growth together with a prolonged period of generative development.Effets d'un traitement au DNOC sur la croissance, le développement el le rendement d'un seigle d'hiver

Effects of nitrogen, phosphorus and potassium on the spike differentiation and development in wheat plants

The effects of nitrogen, phosphorus and potassium on the so called differentiation and its development were investigated cyto-histologically, using Satsukl a variety of wheat. Sand culture was carried out with several kinds of nutrient solutions. Dr. ISHIZUKA'S culture solution which wvas used for physiological study of wheat plants was adopted as the standard and the following eight plots were provided, (1) PK, (2) 1/4NPK, (3) 3 NPK, (4) NK, (5) N3PK, (6) NP, (7) NP3K and (8) NPK, the control. The developmental process of wheat shoot apex can be devided into three main stages in terms of changes in form and structure. In the first stage the apex elongates gradually and its organization is not so evident. The inception of leaf primordia occurs slowly. In the second stage, the apex extends very rapidly and fundamental structure is established in it. This structure is characterized by the presence of three-layered tunica which mantles less-developed corpus or core. According to SHARMAN'S nomenclature these layers of tunica correspond to dermatogen, hypodermis and subhypodermis. The primordia of upper leaves and bracts initiate rapidly in this stage. In the third stage, the stratified layers of tunica receive some disturbances due to all directional division of cell, and results in the decreasc of the number of tunica layers. On the other hand, the number of cells in corpus becomes to increase becausc of the active all directional cell divisions in it. At this stage the form of apex changes shorter in length and broader in width. The differentiation of spikelct primordia begins in the middle of young spike at first and extends toward basipetal and acropetal directions successively and the apex itself turns to a terminal spikelct finally. Nitrogen, phosphorus and potassium are shown to have some specific effects on each developmental stage. Above all, nitrogen and phosphorus form a strong contrast in their effects. Nitrogen tends to accelerate the progress from the first stage to the second stage, but retards the transition to the third stage, delaying thc period of spikelet primordia differentiation. On the contrary, phosphorus tends to accelerate the transition from the second stage to the third stage and phosphorus deficiency delays the period of spikelet primordia differentiation remarkably. This relation suggests that phosphorus has an important physiological role in the transition from vegetative to reproductive stage in wheat plants. These results are basically the same as those obtained with rice plants.

FROZEN DAMAGE OF YOUNG WHEAT SPIKE AND ITS INFLUENCE UPON THE GROWTH.

Frozen damage of young wheat spikes and its influence upon the growth have been studied. The results are briefly summarized as follows. Both the Spring Wheats and Winter Wheats were equally suffered frozen damage by cold temperature (below zero) when the young spikes reached the stage of differentiation of the parts in the flower, that is to say the initials of stamens can be seen as round papillae in the most advanced flower, or the differentiation more advanced. But the spikes that were not reached the differentiation as described above, were relieved of the damage. The damage was larger in Spring Wheats and early sown wheats because the differentiation was more quicker. By these damage, when it was early and great, the growth of the plants was stopped for a time, the large number of small and weak stems were appeared, the escape of ear became remarkably irregular, and the yields were greatly diminished. But when the damage was slight (in lately sown Spring Wheats and early sown Winter Wheats the damage was slight) the influences were not so remarkable. From these results it may be said in our district that in Spring Wheats late sowing is safety, and in Winter Wheats early sowing is profitable but there is a certain limit by the frozen damage.

Studies on hormones

1. Hormones of the spikes of wheat extracted at four different stages,viz., (a) Young spikes enclosed within the leaf-sheath, (b) Pre-anthesis (c) Anthesis, (d) Post-anthesis,i.e., 15 days after pollination, were injected into the leaves, of ages synchronising with the 4 stages of the plant. 2. The injections of the extracts at the first two stages did not bring about any significant difference in their respiratory activity. But the extracts at the two subsequent stages,viz., Anthesis and Post-anthesis had a marked effect; with this difference that the extract at stage 3 brought an immediate enhancement of the respiratory activity while at the 4th stage it reached its maximal at the end of 24 hours. 3. The hormone extract increases the hydrolysis facility of both the proteins and carbohydrates.