Essential oil variation of cultivated and wild Perilla analyzed by GC/MS

Twenty components extracted from the essential oil in the leaves of 172 samples of Perilla frutescens var. crispa (vegetable crop form), P. frutescens var. frutescens (oil crop form), the wild/weedy form of P. frutescens, and three wild Perilla species, Perilla citriodora, Perilla hirtella and Perilla setoyensis were analyzed using GC/MS. A wide range of essential oil components were found among the wild/weedy form of P. frutescens, whereas distinctive components were detected in each wild Perilla species. Egomaketone, asaron, methyleugenol and 4,6-dimethoxy- or 4,7-dimethoxy-5-(2-propenyl)-1,3-dioxaindan were detected from Perilla for the first time. Limonene derivatives, piperitone and piperitenone, were detected from P. citriodora. Discovery of the limonene derivatives in this Perilla species provides evidence of this wild species being a genome donor of P. frutescens, while limonene synthase has been considered to be a specific enzyme in cultivated P. frutescens. These results will be useful for the evaluation and utilization of Perilla genetic resources.     

PHOTOPERIODISM IN AMARANTHUS CAUDATUS. I. A RE-EXAMINATION OF THE PHOTOPERIODIC RESPONSE

Zabka , George G. (State U. Iowa, Iowa City.) Photoperiodism in Amaranthus caudatus. I. A re-examination of the photoperiodic response. Amer. Jour. Bot. 48(1): 21–28. Illus. 1961.—Under the conditions described in this study, Amaranthus caudatus is not subject to inductive short days until it has reached its “sensitive period” or age which is approximately 30 days after the time of germination. Beyond this sensitive period, 2 days are sufficient to initiate inflorescence primordia. Macroscopic identification of this response is possible 2–3 days later, if the plants are retained on short photoperiods. Continued development of the inflorescence is also promoted by short days. This species will also initiate inflorescence primordia on long days of 18 hours duration approximately 60 days beyond germination. Consequently, this is not an obligate short-day plant as previously described. Although A. caudatus will initiate primordia on long days, subsequent normal development of the inflorescence proceeds only under short photoperiods. Plants initiating primordia on long or short photoperiods and then placed on long photoperiods will produce inflorescences which are stubby, generally recurved and spread at the apices. Subsequent flowering and seeding is also delayed. Plants initiating primordia on long days and then placed on short days develop mature inflorescences rapidly but they are divided at the apices and exhibit numerous basal branches.     

Identification of genetic variations of cultivated and weedy types of Perilla species in Korea and Japan using morphological and SSR markers

To better understand the genetic diversity and relationships of the two cultivated types of Perilla crop and their weedy types in Korea and Japan, we evaluated the genetic variations of 56 accessions by assessing five morphological characteristics and 18 SSR markers. The two cultivated types of var. frutescens and var. crispa were clearly distinguished by seed size, whereas most accessions of cultivated and weedy types of var. crispa cannot be distinguished strictly by seed characteristics. A total of 165 alleles with the SSR analysis were detected with an average number of 9.2 alleles per locus among the 56 Perilla accessions. The number of alleles per locus ranged from two for KWPE-56 and KWPE-39 to 21 for GBPFM-204. Additionally, the genetic diversity of each locus ranged from 0.497 at KWPE-56 and KWPE-39 to 0.959 at GBPFM-204, with an average of 0.692. The average genetic diversity values were 0.549, 0.685, 0.451 and 0.557 for cultivated and weedy types of var. frutescens and for cultivated and weedy types of var. crispa, respectively. The weedy type accessions of var. frutescens and var. crispa evidenced greater variation than the corresponding cultivated type accessions. The accessions of the cultivated and weedy types of var. frutescens and var. crispa from Korea exhibited greater SSR diversity than those of Japan. An UPGMA phylogenetic tree revealed three major groups, which was congruent with their morphological characteristics except for a few odd accessions. SSR markers clarified the genetic relationships between var. frutescens and var. crispa and helped improve our understanding of the genetic diversity of the two cultivated types of P. frutescens and their weedy types in Korea and Japan.     

Contributo alla flora del valdarno superiore

Summary

Considering variously aged individui of the short-day plants Chenopodium amaranticolor Coste et Rein, and Perilla ocymoides Lour. var. nanckinensis Voss., researches were carried out concerning differences in photoperiodic behaviour due to ontogenetical progress and other conditions.

Experiments showed that plants behave photoperiodically in a quantitative different manner in relation to age degree. In connection with ontogenetic progress there is a lowering in the minimal anto-inductive number of fotocicli (short day); if a series of fotocicli is given, the minimal duration of the photophase, as well as the need of light intensity, are also lowered. Chenopodium plants, cultivated during 14 weeks in long days, shows — as an extreme manifestation — the ability to form inflorescence primordia even only after one photoinductive ciclus treatment. (i. e. one 16-hours nictophase). Perilla plants cultivated during 16 weeks in long days (more aged plants were not taken into consideration) are able to form inflorescence primordia after 3 photo-inductive cicli (12-hours nictophases). Also these plants, nevertheless, form infl. primordia by means of the action of one nictophase solely, provided this nictophase is cospicuosly prolonged beyond the critical duration; the nictophase shows, in this case, a florigenic action (of particular character: see below) that goes further quantitatively in connection with the exceeding prolongation of conditions of darkness beyond the critical point. The samething may be said for Chenopodium 10-weeks old plants (that do not form infl. primordia with one nictophase of 16 hours). All these tests are able to form infl. primordia in continuous darkness and, always in dark conditions, form possibly flower and liable seeds. Young individui do not behave as aged ones. The age is not the only requisite that grants to the plants this behaviour; such characteristics depends also on the general conditions of nutrition, etc.; therefore, according to the conditions of culture, plants will have the same prerogatives at differents ages.

As to the problem of mechanism under which the infl. primordia formation and flowering is afforded in continuous darkness, and in general in connection with the causes determining the variations in photoperiodical behaviour with aging, many possibilities are discussed. Special importance has been granted to the fact that the individuus, with aging, becomes by and by anto-autonomous (at various degrees) owing to the slow accumulation of eu-florigenic materials formed in long-day conditions.

The anto-autonomous plants are able to form infl. primordia, in darkness, even leaveless (plants deprived of leaves before the treatment): storage occurs expecially in the stem or stock; the storage eu-florigenic substances may be considered simply trophic substances, but of a certain composition and quantity.

The anto-autonomous plant, even at a high degree, do not flower in long-day condition owing to a mechanism of pure photoperiodic anto-inhybition. In continuous darkness it flowers essentially owing to the euflorigenes reserves (a positive factor) and — at the same time — owing to the inability of leaves and stem parenchims to actualise any antiflorigenic process (negative factor).

Many problems are object of discussion and will be bound to further experimental work. Thus the behaviour of leaves in continuous darkness or in a dark-period prolonged beyond the critical point. The leaves of aged plants do not seem to remain, in this case, merely actionless in as much as it concerns the developmental processes.     

Phloem Exudate of Perilla crispa and its Effects on Flowering of P. crispa Shoot Explants

The aim was to develop an assay for the flowering stimulus ofa photoperiodically-sensitive plant. Phloem exudate solutionswere obtained from photoperiodically induced and non-inducedleaves of Perilla crispa (Thunb.) Tanaka, following treatmentof excised leaves with solutions of EDTA or phytic acid. Theamounts of exudate obtained were estimated polarimetrically,and the conditions for obtaining maximum exudate yields weredetermined. Shoot explants from non-induced P. crispa plantswere grown on a nutrient medium. Under short days the explantsreached anthesis after c. 35 d. In continuous light a smallproportion of the explants showed signs of flowering after 100d. The effects of test substances and phloem exudate on theflowering of explants grown in continuous light was investigated.(?)-ABA (4.0 µM), sucrose (14.6 mM) and phloem exudatefrom both induced and non-induced leaves caused some promotionof flowering. In three experiments, phloem exudate from inducedleaves enhanced flowering to a greater extent than exudate fromnon-induced leaves; in other experiments the effects of thetwo types of exudate were similar. There was no evidence thatABA or sucrose in the phloem exudate caused flowering. Concentrationsof phloem exudate above 2.0 g I^–1 were phytotoxic to theexplants. Key words: Chelating agents, Flowering, Perilla crispa, Phloem exudate, Phytic acid, Shoot culture     

Phenotypic and Genetic Diversity of Local <Emphasis Type="Italic">Perilla</Emphasis> (<Emphasis Type="Italic">Perilla frutescens</Emphasis> (L.) Britt.) from Northern Thailand

Phenotypic and Genetic Diversity of Local Perilla ( Perilla frutescens (L.) Britt.) from Northern Thailand. Perilla frutescens (L.) Britt., an important oil and culinary crop in Asia, is a valuable genetic resource. Despite its nutritional value and historic and cultural importance, research on Perilla has been scarce, particularly as far as its genetic diversity is concerned. The aims of the present study were to assess variability within and between 29 seed samples of P. frutescens collected from farmers in northern Thailand, and evaluation conducted of their genetic, morphological, and agronomic characteristics, and the seed composition, including polyunsaturated fatty acids omega-3, omega-6, and omega-9, and the vitamin E γ-tocopherols. Perilla frutescens (L.) Britt. of northern Thailand is genetically variable, and structured according to origin of collection which was the consequence of local adaptation. The discovery of high levels of polyunsaturated fatty acids, namely α-linolenic acid and γ-tocopherols, in some Perilla samples indicates the potential for utilizing Perilla for its high omega-3 content including as a vitamin E supplement for humans, a prospect that should be taken into account when planning conservation strategies or when Perilla variability is used in breeding programs.     

Photoperiodic Regulation of Flowering in Cowpeas (Vigna unguiculata (L.) Walp.)

To test the proposition that photoperiodic controls synchronizethe flowering of cowpeas, Vigna unguiculata (L.) Walp. [V. sinensis(L.) Savi], the day-length requirements for floral initiationand for flowering were investigated in several short-day accessions.No evidence was found of different critical photoperiods atdifferent stages of development, but exposure to only 2–4short days was required for floral initiation compared withabout 20 for development to open flowers. Pod setting was increasedafter exposure to even one short day more than the number requiredfor flower opening. Floral buds at higher nodes appeared to require fewer shortdays for development to flowering than buds at the lower nodes,and displayed faster rates of development. Inflorescence budsdid not resume development if they were exposed to 15 or morelong days following inflorescence initiation. Thus, any tendencytowards synchronous flowering in cowpeas is not due to the criticalday-length for flower development being shorter than that forflower initiation, but could be the result of cumulative photoperiodicinduction of plants and the more rapid development of later-formedflowers. Vigna unguiculata (L.) Walp., cowpeas, flower initiation, flower development, fruit set, photoperiodism     

Arabidopsis late-flowering fve mutants are affected in both vegetative and reproductive development

The development of wild-type Arabidopsis thaliana (L.) Heyhn and two late-flowering fve mutants has been analysed under different environmental conditions. In wild-type plants, short-day photoperiods delay the floral transition as a consequence of lengthening all the developmental phases of the plant. Moreover, short days also alter the inflorescence structure by reducing the internode elongation and delaying the establishment of the floral developmental programme in the lateral meristems of the inflorescence and co-florescences. Mutations at the FVE locus cause a delay in flowering time, and a change in the inflorescence structure, similar to the effect of short photoperiods on wild-type plants. However, the effect of the fve mutations is additive to the effect of short days, and all the aspects of the Fve phenotype are corrected by vernalization. These results seem to indicate that FVE is not simply involved in timing the transition from vegetative to reproductive growth, but that it could play a role during all stages of plant development.     

Flowering strategies of the high-arctic and high-alpine snow bed grass species Phippsia algida

Flowering requirements of the high-arctic and high-alpine snow bed grass species Phippsia algida (Sol.) R. Br. have been studied in controlled environments. Seedlings flowered rapidly in continuous long days (LD) at temperatures ranging from 9 to 21°C. They also initiated inflorescence primordia at the same temperatures in continuous short days (SD), whereas LD were required for heading and anthesis. The plant thus has the characteristics of a regular long day plant, although the daylength requirement is associated with floral development only. The critical daylength for the LD response was about 17 h at 21°C and 19 h at 9°C. A single LD cycle was enough to trigger inflorescence development, while 5 cycles were required for the full response. Anthesis was reached within a week of LD treatment at 21°C in SD grown plants with preformed inflorescence primordia. The advantages of these versatile flowering responses are discussed in relation to the extreme climatic regime of late snow bed sites.     

Bi-directional inflorescence development inArabidopsis thaliana: Acropetal initiation of flowers and basipetal initiation of paraclades

In this study we investigated Arabidopsis thaliana (L.) Heynh. inflorescence development by characterizing morphological changes at the shoot apex during the transition to flowering. Sixteen-hour photoperiods were used to synchronously induce flowering in vegetative plants grown for 30 d in non-inductive 8-h photoperiods. During the first inductive cycle, the shoot apical meristem ceased producing leaf primordia and began to produce flower primordia. The differentiation of paraclades (axillary flowering shoots), however, did not occur until after the initiation of multiple flower primordia from the shoot apical meristem. Paraclades were produced by the basipetal activation of buds from the axils of leaf primordia which had been initiated prior to photoperiodic induction. Concurrent with the activation of paraclades was the partial suppression of paraclade-associated leaf primordia, which became bract leaves. The suppression of bract-leaf primordia and the abrupt initiation of flower primordia during the first inductive photoperiod is indicative of a single phase change during the transition to flowering in photoperiodically induced Arabidopsis. Morphogenetic changes characteristic of the transition to flowering in plants grown continuously in 16-h photoperiods were qualitatively equivalent to the changes observed in plants which were photoperiodically induced after 30 d. These results suggest that Arabidopsis has only two phases of development, a vegetative phase and a reproductive phase; and that the production of flower primordia, the differentiation of paraclades from the axils of pre-existing leaf primordia and the elongation of internodes all occur during the reproductive phase.     

Obligatory short‐day plant,Perilla frutescens var. crispa can flower in response to low‐intensity light stress under long‐day conditions

An obligatory short‐day plant, Perilla frutescens var. crispa was induced to flower under long‐day conditions when grown under low‐intensity light (30 µmol m^?2 s^?1). Plant size was smaller under lower light intensity, indicating that the low‐intensity light acted as a stress factor. The phenomenon is categorized as stress‐induced flowering. Low‐intensity light treatment for 4 weeks induced 100% flowering. The plants responded to low‐intensity light immediately after the cotyledons expanded, and the flowering response decreased with increasing plant age. The induced plants produced fertile seeds, and the progeny developed normally. The plants that flowered under low‐intensity light had greener leaves. This greening was because of the decrease in anthocyanin content, and there was a negative correlation between the anthocyanin content and percent flowering. Treatment with L‐2‐aminooxy‐3‐phenylpropionic acid, an inhibitor of phenylalanine ammonia‐lyase (PAL), did not induce flowering under non‐inductive light conditions and inhibited flowering under inductive low‐intensity light conditions. The metabolic pathway regulated by PAL may be involved in the flowering induced by low‐intensity light.     

The Control of Flowering, Growth, and Dormancy in Kleinia articulata by Photoperiod

Kleinia articulata subjected to different photoperiods becomesdormant in long days (continuous light) and grows uninterruptedlyin short days (8 h). Dormancy results from the rapid cessationof leaf differentiation and expansion. By contrast stem growthis faster in long days and continues until all leaves have died.In long days growth is not halted permanently but flushes ofleaf production and stem elongation occur. Resumption of growthis stimulated rapidly by total darkness or short-day treatmentof the extreme stem tips for some days. This species is a strictshort-day plant in its flowering behaviour, depending on thisdaylength for normal inflorescence development also.     

EXPERIMENTAL CONTROL OF FLOWERING IN LEMNA. II. SOME EFFECTS OF MEDIUM COMPOSITION,CHELATING AGENTS AND HIGH TEMPERATURES ON FLOWERING IN L. PERPUSILLA 6746

Hillman , William S. (Yale U., New Haven, Conn.) Experimental control of flowering in Lemna. II. Some effects of medium composition, chelating agents and high temperatures on flowering in L. perpusilla 6746. Amer. Jour. Bot. 46(7): 489–495. Illus. 1959.—-L. perpusilla 6746 flowers as a short-day plant on Hutner's medium (containing ethylenediaminetetraacetic acid [EDTA]) at constant temperatures from 25 to 30°C., but eventually flowers also in old cultures under 16 or 24 hr. of light. This old-culture flowering is more pronounced in dilute medium. Flowering is rapid under both long and short days at constant temperatures from 25 to 28°C. in media not containing EDTA; the addition of 10^-5 M EDTA or of similar or higher concentrations of numerous other chelating agents suppresses flowering under long days but not under short (8 hr. light). This effect does not depend on promotion or inhibition of vegetative growth. At 29 to 30°C., a short-day requirement is manifested even in media permitting flowering under long days at the lower temperatures. Temperatures above 31°C. completely inhibit flowering under all conditions. Brief periods of high temperature given to plants under short-day conditions inhibit flowering when given during the dark period but not during the light period. The implications of these observations for the further study of flowering are discussed.     

Effect of Low-intensity Red and Far-red Light and High-intensity White Light on the Flowering Response of the Long-day Plant Lemna gibba G3

The long-day plant Lemna gibba L., strain G3 exhibits a relatively low sensitivity to short, white-light interruptions given during the dark period of a short-day cycle. However, the plants are fairly sensitive to low-intensity red light treatments given during a 15-hour dark period on the third day of a 2LD-(9L:15D)-2LD-7SD schedule. Far-red light is almost as effective as red light, and attempts to reverse the red light response with subsequent far-red light treatments have not been successful. Blue light proved to be without effect. When plants were grown on a 48-hour cycle with 15 minutes of red light every 4 hours during the dark period, the critical daylength was reduced from about 32 hours to slightly less than 12 hours.

Continuous red light induced a fairly good flowering response. However, as little as 1 hour of white light each day gave a significant improvement in the flowering response over that of the continuous red light control. White light of 600 to 700 ft-c was more effective than white light of 60 to 70 ft-c. The white light was much more effective when divided into 2 equal exposures given 8 to 12 hours apart. These results suggest an increase in light sensitivity with regard to flower induction about 8 to 10 hours after the start of the light period.

     

Flowering requirements of Scandinavian Festuca pratensis

Flowering requirements of three Scandinavian cultivars of Festuca pratensis Huds, have been studied in controlled environments. At 3 and 6°C, primary induction was independent of photoperiod, while short days (8 h) were more effective than long days (24 h) at higher temperatures. The critical temperature for induction was about 15°C in short days and about 12°C in long days. Saturation of induction required 18–20 weeks of exposure to optimal conditions. At temperatures below 12°C both induction and initiation of inflorescence primordia took place in long days, while a transition to long days was required for inflorescence initiation after primary induction in short days. A minimum of 8 long-day cycles were required for flowering of plants primary induced in short days and saturation of flowering required more than 16 cycles. The critical photoperiod for secondary induction was about 13 h. High temperature (21°C) had some devernalization effect in primary induced plants, suppressing flowering compared with 15°C.     

Promotion and Inhibition of Inflorescence Growth by Long Days in Short-day Plants

Results of previous investigators have indicated that long periodsof light intercalated between inductive short-day cycles havean inhibitory effect on inflorescence growth in short-day plants.The present experiments show that such light periods can eitherpromote or inhibit inflorescence growth in Xanthium pemtsylvanicumand Chenopodium amaranticolor depending on their previous degreeof induction. Intercalated light exerts an inhibitory influence on the inductiveprocesses occurring during the dark period which follows itwhen unifoliate Xanthium plants have been previously exposedto not more than one short day and when fully foliated Chenopodiumplants have been previously exposed to not more than one ortwo short days. When plants are more strongly induced initially,an intercalated light period has a very marked promoting effecton the dark period succeeding it. In Xanthium this stimulatoryeffect increases with the duration of the light period up toan optimum of approximately 80 hours. It is suggested on the basis of available evidence that thepromotive effect of such intercalated light possibly affectsthe sensitivity of the apex to inductive stimuli and that itsinhibitory effect acts on the inductive processes occurringin the leaves.     

Flowering of Cultivated Green and SAN 9789-Treated Chenopodium rubrum Plants Exposed to White,Blue, and Red Light

Green plants and plants devoid of photosynthetic pigments were compared with regard to their ability to flower under various growth conditions. Green plants of Chenopodium rubrum L. and plants treated with norflurazon SANDOZ-9789 (SAN) were grown on sucrose-containing media with or without hormones (GA₃, BA, IAA, ABA) under short-day photoperiodic or continuous illumination with white, blue, or red light. Green and SAN-treated albino plants produced flowers only under short-day conditions. The flowering of green plants was independent of the presence of sucrose and hormones in the medium as well as of the light quality. The albino plants produced flowers under white and blue light but did not flower in red light. The addition of GA₃ or BA to the medium induced flowering of albino plants exposed to red light. The functional interaction of photoreceptors in the flowering control is discussed.     

Influence of timing and number of consecutive inductive photoperiodic cycles on the flowering of lemna

Requirements for flowering of the short day plant Lemna perpusilla Torr. strain 6746 can be studied by interposition of varying numbers of consecutive short days during 7 days of continuous light. A single inductive cycle can cause the formation of few flowers if it comes during the middle of a 7-day period of continuous light. Three inductive cycles cause 30% or more of the fronds to flower if the cycles are properly spaced in the 7-day period. The fact that timing of the inductive photoperiodic cycles is critical indicates the importance of development time and abortion of evoked floral primordia in the flowering response. These results are particularly useful in studies of processes occurring during induction.     

REVERSION AND REINDUCTION OF FLOWERING IN PERILLA

Lam , S. L., and A. C. Leopold . (Purdue U., Lafayette, Indiana.) Reversion and reinduction of flowering in Perilla. Amer. Jour. Bot. 48(4): 306–310. Illus. 1961.—Plants of Perilla crispa (Thunb.) Tanaka ultimately revert to the vegetative state provided that they have received not more than about 20 cycles of short photoperiods. Reversion is markedly promoted by repeated debudding of plants induced with 35 cycles or less. Reverted plants of Perilla could be reinduced twice by photoperiodic treatment of the originally induced leaves. Timing experiments to measure the flow of flower stimulus from induced leaves suggest a gradual loss of the stimulus, as indicated by increased time to appearance of flowers and decreased flower number. It is concluded that after the inductive treatment is withdrawn, the effectiveness of the flower stimulus coming from the leaf declines with time. It is suggested that reversion is made possible by the decline of effective flower stimulus coming from the induced leaves.