Blade Margin Research Articles

HAIRY‐SHEATH FRAYED #1‐O: A SYSTEMIC, HETEROCHRONIC MUTANT OF MAIZE THAT SPECIFIES SLOW DEVELOPMENTAL STAGE TRANSITIONS

Hairy sheath frayed‐1 (Hsf1‐O), an ethyl methanesolfonate‐induced dominant mutant in maize, was first described as an excessively hairy plant with pronglike projections of sheath that extended from the margin of the leaf blade. We describe several other phenotypes and show that Hsf1‐O affects virtually every segment of the plant. We have identified genetic backgrounds that suppress some of the Hsf1‐O phenotypes. The morphological descriptions reveal a prolongation of cell differentiation in certain tissues and organs. In general, transformations are from more adult to more juvenile, not older to younger. On the assumption that Hsf1‐O acts with the same developmental logic in both the apical meristem and leaf primordia, the leaf sheath is a juvenile blade, not a young blade. Genetic background effects show that the expressivity of the phenotype is influenced by the plant's time to anthesis. The suppression and temporal shift in Hsf1‐O expression patterns in early flowering lines is due to the inherent accelerated maturation of cells in these lines. In early flowering lines, transformations are suppressed and shifted toward the less mature (younger) tissues, organs, and segments of the plant. We conclude that Hsf1‐O is a heterochronic mutation that prolongs the time to maturity (delays terminal differentiation), and that a primordial cell's developmental maturity rather than the cell's position can dictate that cell's fate. Hsf1‐O disconnects the rate of developmental stage transition from the overall flowering‐time rate.

Hairy-Sheath Frayed # 1-0: A Systemic, Heterochronic Mutant of Maize that Specifies Slow Developmental Stage Transitions

Hairy sheath frayed-1 (Hsf1-O), an ethyl methanesolfonate-induced dominant mutant in maize, was first described as an excessively hairy plant with pronglike projections of sheath that extended from the margin of the leaf blade. We describe several other phenotypes and show that Hsf1-O affects virtually every segment of the plant. We have identified genetic backgrounds that suppress some of the Hsf1-O phenotypes. The morphological descriptions reveal a prolongation of cell differentiation in certain tissues and organs. In general, transformations are from more adult to more juvenile, not older to younger. On the assumption that Hsf1-O acts with the same developmental logic in both the apical meristem and leaf primordia, the leaf sheath is a juvenile blade, not a young blade. Genetic background effects show that the expressivity of the phenotype is influenced by the plant's time to anthesis. The suppression and temporal shift in Hsf1-O expression patterns in early flowering lines is due to the inherent accelerated maturation of cells in these lines. In early flowering lines, transformations are suppressed and shifted toward the less mature (younger) tissues, organs, and segments of the plant. We conclude that Hsf1-O is a heterochronic mutation that prolongs the time to maturity (delays terminal differentiation), and that a primordial cell's developmental maturity rather than the cell's position can dictate that cell's fate. Hsf1-O disconnects the rate of developmental stage transition from the overall flowering-time rate.

Altered Middle Lobe Shape of Leaf Permits Rapid Diagnosis of Grapevine Fanleaf in Grapevine cv. St. George

When potted plants of cv. St. George infected with grapevine fanleaf virus (GFV) were kept under the temperature conditions of 28/23C (day/night) or 20/17C, the newly developed leaves did not show typical symptoms of GFV such as wide petiole sinus, asymmetrical blade shape and leaf blades assuming the shape of a fan until 50 days after sprouting. The denticulation of the margins of the leaf blades on infected plants also showed almost no difference from those of healthy plants during the 50 days. However, the middle lobe cusps of these leaves on the infected plants were very acute after the above incubation period, and clearly different from those of healthy plants. The symptoms appeared faster under the higher temperature condition of 28/23C than under the lower temperature condition of 20/17C. Sharpening ratios for the cusps of the middle lobes of infected and healthy leaves were compared. Infected plants were indicated by ratios exceeding 2.6 in the 50 days period. On the other hand, healthy plants were indicated by ratios less than 2.6. A sharpening ratio of 2.6 was converted into a value of 42.4 degrees for the angle of the middle lobe cusp of a leaf. Grapevine fanleaf can be rapidly diagnosed in cv. St. George within a period of 50 days after sprouting on the basis of the following criteria. At temperatures of 28/23C, values below 42.4 degrees for the angle of the middle lobe cusps of three successive leaves from the fourth to the sixth in leaf order from the base of a shoot indicate infection with grapevine fanleaf virus. The measurement of this angle is easily made by using a magnifying glass with a V mark of 42.4 degrees, or with the naked eye.

Austrofolium gen. nov. (Delesseriaceae, Rhodophyta) from the Pacific Coast of South America

Austrofolium Wynne, gen. nov. contains three species of foliose red algae occurring on the coast of Peru and the Galapagos Islands. Austrofolium hassleri (W. Tayl.) Wynne, comb. nov. (Hemineura hassleri W. Tayl.) is designated the type of the genus. Austrofolium howellii (W. Tayl.) Wynne, comb. nov. (Hemineura (?) howellii W. Tayl.) and A. equatorianum (E. Y. Daws.) Wynne, comb. nov. (Bartoniella (?) equatoriana E. Y. Daws.) are also assigned to the new genus. The absence of intercalary cell divisions and the failure of some tertiary initials to reach the blade margin demonstrate that Austrofolium is a member of the Membranoptera group of subfamily Delesserioi- deae. The blades become polystromatic relatively close to the apex. In the course of examining members of the Delesseriaceae I have recognized that three species described from Peru and the Galapagos Islands have been incorrectly assigned to genus. The purpose of this paper is to re-describe these species, paying particular attention to their api- cal organization, and to present reasons justi- fying the delineation of a new genus to accom- modate them. The three species in question are Hemineura (?) howellii W. Tayl., Hemineura hassleri W. Tayl., and Bartoniella (?) equatoriana E. Y. Daws. The genus Hemineura was established by Har-

The importance of plant defence abilities to the structure of subtidal seaweed communities: The kelp Laminaria longicruris de la Pylaie survives grazing by the snail Lacuna vincta (Montagu) at high population densities

Following mass mortalities of sea urchins, Strongylocentrotus droebachiensis (Müller), in the rocky subtidal of the Atlantic coast of Nova Scotia, dense seaweed beds dominated by the canopy-forming kelp Laminaria longicruris de la Pylaie developed for the first time in several years. The numerically abundant grazers in the seaweed beds when sea urchins were rare were the mesogastropod Lacuna vincta (Montagu), the limpet Notoacmaea testudinalis (Müller), and the chiton Tonicella rubra (Linné). The limpet and chiton are unable to graze the macroscopic sporophytes of Laminaria, and a manipulation experiment showed that they have no significant effect on the recruitment of this kelp. In contrast, Lacuna grazes the macroscopic sporophyte and several of its population characteristics suggested that it might be a potentially important grazer of Laminaria. Snails can occur in high densities and several invasions of an area may occur during a single season; they manifest strong preference for Laminaria in the subtidal region; post-metamorphic individuals have considerable ability for dispersal; and predation by their principal predator, the labrid fish Tautogolabrus adspersus (Walbaum) is limited in time and space. Despite this potential, the estimated direct consumption of kelp laminae by snails was negligible, amounting to only ≈ 0.05 % of the total blade biomass (fresh wt) that was available during their season. However, the snails′ overall impact on the Laminaria canopy was significant. Because grazing was concentrated on the frilled margins of laminae, and the holdfast, stipe and intercalary meristem were largely avoided, grazing promoted the tearing away of the margins of blades, resulting in a significant reduction in canopy area without increasing kelp mortality. Since there was no grazer-induced mortality of Laminaria, the canopy was closed following the growth burst of the kelps early in the spring, and there was little opportunity for understorey species to benefit from the temporarily high light levels. If the distribution of grazing by the snails had been more uniform and caused significant mortality of Laminaria, major changes in the structure of the seaweed assemblage would have occurred. We suggest that the pattern of Lacuna grazing on Laminaria is governed by the distribution of anti-herbivore chemicals in the plants, and variations in the toughness and nutritional quality of different regions of the plant. Avoidance of the intercalary meristem correlates with high levels of polyphenols in this area. Polyphenol concentration is uniformly low throughout the rest of the plant. The distribution of snail grazing on the stipe and holdfast, and central and lateral portions of the lamina correlates with the toughness and nutritional quality of these parts. The nature of the anti-herbivore defences of Laminaria, which are effective against grazing by Lacuna but not by the urchins, indicates a trade-off between high specific growth rates and reproductive output (and thus superior competitive ability) versus development of defences. This strategy is consistent with cost-effective arguments relating resource allocation and fitness.

Ein Beitrag zur Infektionsbiologie des durch Scleroderris lagerbergii verursachten Schwarzkieferntriebsterbens

A contribution to the infection biology of dieback of Pinus nigra caused by Scleroderris lagerbergii Gr. In the buds the dead cells of the blade margins of the scales are first invaded. In December the fungus grows into the living parenchyma cells of the scales (cataphylls). In the long shoots hyphae could be observed in the cells of the epidermis and hypodermis in August, and in January of the year following infection the living tissue of the primary cortex (cortex parenchyma) is invaded at and between the needle bases.

OnLaminaria saccharina from Hokkaido

During February 1973 we collected a species ofLaminaria at Koetoi, Wakkanai, Hokkaido lacking mucilage ducts in the stipe and not having a conspicuous median fascia. These two features are shared withL. yendoana Miyabe (Miyabein Okamura, 1936, p. 288). However, the Koetoi plants have a cuneate blade base, smooth blade margin and relatively thick haptera. These features differ fromL. yendoana which has a truncate-cordate blade base, undulate blade margin and very fine haptera. Our specimens were collected from a locality known to be inhabited byL. cichorioides Miyabe. However, theL. cichorioides species has mucilage ducts in the stipe, a truncatecordate blade base and a crispate blade margin, all of which distinguish this species fromL. saccharina. Of those taxa described from the northwest Pacific,Laminaria saccharina f.linearis J. Agardhsensu Tokida, 1954 is the most similar to the Koetoi plants. The purpose of the present report is to describeL. saccharina f.linearis from Koetoi and discuss its relationship to plants of the same taxon found elsewhere.

昆布葉体の無機成分の分布-II

Anionic constituents of the ash from the four parts (base, center, margin, and apex) of kombu blade were determined. The samples analysed were harvested on the same seashore and in the same season as those analysed for metallic ions in the previous study. The results obtained were as follows: Cl, 32-40; SO4, 5-8; I, 1-6, ; CO3, 0.7-10; PO4, 0.6-1.7% of soluble matter. Total amounts of these anions reached 49-58% of the soluble ash. The contents of I, CO3, and PO4 were higher in the base and center than in the margin and apex. The reverse tendency was observed for the content of SO4, but no significant, differences in Cl content were recognized. Total amounts of metallic ions and anions ranged from 94 to 107%. Comparison with MCCollum's salt showed that the kombu blade was rich in Na and Cl, while poor in Ca, Fe, and P04.

Stamen-carpel Homologies

The study of intermediate phyllomes (stamen-carpels) in Salix as well as the reassessment of previous observations lead the author to put forward a general interpretation of homologies between stamen and carpel. The stamen is considered diplophyllous, i.e. with two tangential blades topping an unifacial filament. The four margins of these blades form the four pollen sacs. If the filament were hollow instead of solid, there would arise a congenitally closed cavity as in a peltate carpel. Its back part would bear the posterior blade of the diplophyllous anther, its front portion the anterior blade. The latter is made up of two congenitally fused anterior lobes, one on each side of the fusion line, prolonging the corresponding line of the filament. When the upper parts of the margins are no longer fused along this line in a peltate carpel the ventral split arises and in a diplophyllous stamen the two ventral lobes are freed, as seen in stamen-carpels of Tulipa. When such a process occurs together with disappearance of pollen sacs, ovule formation on the ventral split and merging of the ventral lobes in the posterior (main) blade, a carpel arises whose blade incorporates both posterior and anterior blades of the corresponding stamen (Tofieldia type, Guédès 1965a). When the anterior blade disappears, the posterior blade alone gives birth to the carpellary blade (Sempervium type, also found in Tulipa). In Veronica, Papaver and Salix, the anterior blade proper fades out too, but intermediate appendages arise between its constituting anterior lobes and the posterior blade. The placental appendages fuse with the posterior blade and develop the ovules. Since when the posterior blade of Sempervivum or Tulipa forms such ovules, narrow strips are also added to it distally, the first-mentioned genera must be referred to the Sempervivum type as well. In all these instances, anther and filament may or may not take part in the formation of the fertile carpel portion. The issuing carpel is peltate or depending on to whether or not its blade margins are fused congenitally in their lower part. In teratologically isolated carpels of Salix replacing stamens, the margins are congenitally fused up to the apex with some ovules being borne only basally, and this affords a clue to the interpretation of normal carpels in Typha, the Potamogetonaceae, the Bignoniaceae and the Caryophyllaceae. As far as possible, an ontogenetical interpretation of these phenomena is set forth, taking account of modern views (Dulieu, Guédès) on foliage leaf ontogeny.

AUXIN‐INDUCED HYPONASTY OF THE LEAF BLADE OF PHASEOLUS VULGARIS

The lateral margins of immature primary leaf blades of Phaseolus vulgaris L. cv. ‘Pinto’ curve up and in toward the midrib when auxin is applied to the leaf. The leaves are most sensitive to auxin shortly after they first unfold and leaves which have grown to about 60 % or more of their ultimate area no longer give this hyponastic response. The response is specific for auxins and is inhibited by the anti‐auxins, trans‐cinnamic acid and para‐chlorophenoxyisobutyric acid. Ethylene and ethylene‐generating compounds failed to induce hyponasty, suggesting the response is due to a positive growth promotion by auxin. Measurements of the distance between the lateral margins of the leaf at its maximum width were used to provide quantitative estimates of the degree of hyponasty. Between 2 and 4 hr after auxin application a direct proportionality was found between the amount of curvature and the logarithm of the indoleacetic acid concentration over the range of 10−6 to 10−3 m. The relative sensitivity of the leaves to different auxins was qualitatively similar to that observed in many straight‐growth bioassays. Similar responses were obtained when auxin was applied by a carborundum wounding procedure. Potential applications of this auxin bioassay for investigations of the role of auxin in the normal plagiotropic growth behavior of leaf lamina and of the role of auxin in the initiation of various plant diseases are suggested.

Auxin-Induced Hyponasty of the Leaf Blade of Phaseolus vulgaris

The lateral margins of immature primary leaf blades of Phaseolus vulgaris L. cv. ‘Pinto’ curve up and in toward the midrib when auxin is applied to the leaf. The leaves are most sensitive to auxin shortly after they first unfold and leaves which have grown to about 60 % or more of their ultimate area no longer give this hyponastic response. The response is specific for auxins and is inhibited by the anti-auxins, trans-cinnamic acid and para-chlorophenoxyisobutyric acid. Ethylene and ethylene-generating compounds failed to induce hyponasty, suggesting the response is due to a positive growth promotion by auxin. Measurements of the distance between the lateral margins of the leaf at its maximum width were used to provide quantitative estimates of the degree of hyponasty. Between 2 and 4 hr after auxin application a direct proportionality was found between the amount of curvature and the logarithm of the indoleacetic acid concentration over the range of 10−6 to 10−3 m. The relative sensitivity of the leaves to different auxins was qualitatively similar to that observed in many straight-growth bioassays. Similar responses were obtained when auxin was applied by a carborundum wounding procedure. Potential applications of this auxin bioassay for investigations of the role of auxin in the normal plagiotropic growth behavior of leaf lamina and of the role of auxin in the initiation of various plant diseases are suggested.

ワカメの生態に関する研究-V

It has been widly accested that in the species Undaria pinnatifida SUR., two different forms, f. typica and f. distans, have been. However, the necessary characteristics to differenciate the A-form from B-form have not adequately been clarified. This study was carried out for the purpose of finding out the fittest characteristics useful to indentify these forms. The materials and the method of investigation are as follows: (1) The materials were collected from the fronds which were introduced from various original habitats and cultured by hanging-method in Toyohama Harbour, Chita District, Aichi Pref., and also from the fronds in natural habitat at Toyohama and Ono, in the same district. (2) On these materials, biometrical investigations were made on several portions of the same frond, such as the length of frond (L1), the length of stipe (L2), the distance from the lowest margin of blade to the upper end of sporophyll-part (L3), the width of frond (W: the broadest portion in young fronds; W1: the broadest portion of pinnate blade in adult fronds; W2: the same of basal part of blade), the number of pinnate blade (N1), the number of wrinkle of sporophyll (N2), and the shape of sporophyll etc. (vide Figs. 1, 3 ?? 8). Then, these numerical values and interrelations between some of them were compared among the cultured fronds introduced from three original habitats (Toyohama, Ono and Oginohama, Miyagi Pref.), those between the wild and cultured fronds and also those between the fronds of the first and second generations. The results obtained may be summarized as follows: (1) Obvious differences were recognized among the cultured fronds of above mentioned three habitats on the following items: the ratio of L2/L1, the relationship between N1 and L1, the number of wrinkle of sporophyll and the growth rate of frond. (2) As to the comparision of the wild and cultured fronds at Toyohama and Ono, only a few differences were recognized. They are namely, the ratio of W/L1 and the length of frond at the time when the first wrinkle of sporophyll was formed, in the Toyohama-specimens, and the ratio of L2/L1 in the Ono-specimens. As to the difference between the frond of the first and second generation, it was not recognized in the fronds of Toyohama, but was imperceptively seen on the ratio of L2/L1 and the same of W2/W1 in those from Oginohama. (3) Consequently, it was suggested that the shape of fronds at various habitats were distinguishable especially in such characters as follows: (a) the ratio of L2/L1, (b) the rela-tionship between N1 and L1, (c) the length of frond at the time when the first wrinkle of sporophyll was formed, (d) the relationship between N2 and L1, (e) the number of wrinkle of sporophyll, (f) the growth rate of frond. Besides these marked characteristics were scarcely lost by the culture and also were reiterated for some, at least two, generations.

SUGAR EXCRETION IN IMPATIENS SULTANI

THE EXCRETION of sugar by members of the species Impatiens Sultani was first noticed in plants that were kept in the laboratory for general use. As no mention of the property was found in the literature, a study was made of conditions controlling sugar excretion and of the chemical nature of the sugar. I. Sultani has been grown extensively under glass and as a house plant since a few years after its introduction from Zanzibar by Sir John Kirk (Hooker, 1882). The species was originally described by Hooker (1882), and the first American description was in Vick's Magazine (1884). EXPERIMENTAL PROCEDURE.-Under experimental conditions some of the plants were grown in a greenhouse, and others were kept on the window sills of a room in which the humidity was relatively low. The size of the individual granules of accumulated sugar was greatest on plants in windows receiving sunlight, but fair accumulation was obtained even on those plants kept in north windows. In the greenhouse, accumulation was good as long as the humidity was low. In cloudy weather, however, the humidity was often too high to permit rapid evaporation of water from the droplets of sugar solution that were excreted. Even in clear weather, the hu1 Received for publication May 22, 1939. These experiments were conducted in the botanical and chemical laboratories at Bucknell University, and this opportunity is taken to express sincere appreciation for the use of facilities. midity was at times too high to permit rapid evaporation. All the plants were supplied with plenty of water from below. The plants used were all grown from cuttings of three parent plants-one with solid green leaves and rosecolored blossoms, one with solid green leaves and salmon blossoms, and one with leaves variegated green and white, and rose blossoms. Sugar was first noticed on a plant of the salmon variety, which was obtained in North Carolina. The other varieties were obtained later in Pennsylvania. If the cuttings were well rooted when potted, good sized sugar granules were usually obtained within two or three weeks in a dry atmosphere. The best yields of sugar were obtained after the plants had become well pot-bound. Usually the sugar was not collected until the leaves were ready to be dropped from the plant by abscission, for at that time the granules were of maximum size and were completely solidified. Granules on leaves that were active photosynthetically were difficult to handle, as they were frequently solid and crystalline on the surface, but liquid in the center. Figure 1 shows a branch from a plant of the salmon variety that was grown under conditions favorable to sugar accumulation. It may be observed that the sugar is excreted at the tips of hair-like protuberances located on the sides of the petioles, and to a lesser extent from the tips of the serrations on the margins of the leaf blades. These protuberances are