• Volume 93, Issue 3

July 1984,   pages  189-427

• Factors controlling growth rate of cellulolytic fungi on sterile filter-paper

Cellulolysis rates of four cereal foot-rot fungi were estimated by dry-weight loss (wl) of filter-paper cultures incubated for 7 weeks at 22·5°C. Fungal growth rate across the paper circles was recorded and was found to be correlated with the product of$$\sqrt {WL}$$ of paper multiplied by fungal growth rate overpd agar; the correlation was significant at 1% level.

• The many types of disease resistance

• Spore germination in the higher Basidiomycetes

This survey of the spore germination requirements in the Hymenomycetes and the Gasteromycetes shows that saprophytes as xylophiles, which decompose wood and forest litter, and coprophiles, which live on dung, usually germinate easily even on simple nutrient media. Species forming ectomycorrhiza with trees or living as parasites require as a rule more particular conditions for germination. In the mycorrhiza-formers, chiefly agarics and boleti, germination can often be induced by exudates from tree roots or certain yeasts, in species ofLeccinum by exudate from self mycelium. The heartrot fungi, chiefly those species of Aphyllophorales which are parasites on trees, germinate preferably when exposed to an increased CO2 content in the air or to exudates of certain micro-organisms. In many praticolous fungi, which are supposed to parasitize roots of grasses and herbs, germination is stimulated by various yeasts. The possibility of interpreting these particular germination conditions as adaptations to a parasitic or symbiotic life is discussed.

• Communication problems in interdisciplinary research

Communication in interdisciplinary research ranges from communication between collaborators with different interests and vocabularies, through presenting published conclusions in a form comprehensible to all potential users, to choice of a publication vehicle and facilitating information retrieval.

• Plant cell physiology (1934–84): Recollections and reflections

• Photooxidative destruction of chloroplasts and its consequences for anthocyanin synthesis

Electron microscopic and biochemical evidence is given that phytochrome-mediated formation of juvenile anthocyanin in the epidermis of the cotyledons and in the subepidermis of the hypocotyl of the mustard (Sinapis alba L.) seedling does not depend on intact plastids. Under experimental conditions where the plastid compartment is badly damaged and expression of plastid genes seems impossible anthocyanin formation proceeds normally. It is concluded that neither the plastids nor the vacuole are involved in the process of anthocyanin biosynthesis.

• Physiology of flower bud growth and opening

Flower growth and opening are commonplace events, but physiologically intricate and inadequately explained. In this review, we have brought together and evaluated information on this subject to focus attention on the dynamic facets of flower development. In particular, the physiological basis of flower bud dormancy, nature of cleistogamy, mechanism of flower bud growth and turgor maintenance and role of stamens in corolla growth have been examined. The regulation of flower movements and opening by temperature and light, and circadian rhythms in flower opening have been discussed, along with a consideration of the role of the petal epidermis in light perception.

It is emphasized that studies on flower physiology need to be intensified in view of the lacunae in our basic knowledge as well as to provide a sound basis for improving yields of both agricultural and horticultural crops.

• Photoacoustic characterisation of thein vivo levels of chlorophylla in the adaxial and abaxial sides of the leaf

Photoacoustic spectroscopy was applied to determine the distribution of chlorophylla in the abaxial and adaxial sides of the leaf in 27 species of angiospermous plants. Two distinct patterns were observed in the ratio of the level of chlorophylla in the abaxial to adaxial side of the leaf in the monocotyledons and in dicotyledons plants. The ratio was not correlated with the C3 or C4 type of photosynthetic pathways.

• Psychoactive plants in need of chemical and pharmacological study

Reports on the inebriating properties of plants—some employed in magico-religious ceremonies of primitive societies in various parts of the world—continue to appear. Their sources are many: reports of travellers, anthropological writings, historical documents, herbarium specimens and others. The diversity and wide occurrence of the reports have tended to keep them from the scrutiny of investigators who might have studied the plants for the ascertainment of their active principles.

In an effort to focus attention on some of these presumably psychoactive plants, the following notes are offered. Only those species which seem most urgently in need of attention are listed. There are others which appear to be promising albeit not of such immediate interest because of the vagueness of the ethnobotanical reports of their use or because of extreme difficulty in procuring sufficient supplies of the plant for phytochemical study. Even though the number of species listed below is limited, it is obvious how much remains to be done in the interdisciplinary study of biodynamic plants.

A very recent survey of natural hallucinogens has pointed out that more than 200 species of higher plants comprise the study, that they are widely distributed in the plant kingdom (146 genera in more than 50 families) and that the active principles are known for only about 45 species (Schultes and Farnsworth 1980)Bot. Mus. Leaft., Harvard Univ.28 (186–190). This survey attributes the lack of chemical knowledge of these plants to two causes: (i) the lack of good animal models which the chemist can utilize in monitoring his isolation work; and (ii) the paucity of field work of scientific trustworthiness in fast disappearing aboriginal societies. The survey ends with the statement that the “… Plant kingdom remains a fertile and almost virgin territory for those interested in the discovery of new psychoactive drugs, not to mention other types of biologically active compounds waiting in silent hiding.”

The extreme paucity of phytochemical studies on these plants of very significant use in primitive societies emphasizes one of the most important results from ethnobotanical investigations: the ability to orient chemical analyses along lines of biodynamically useful species.

• The mitochondrial genome of higher plants

The mitochondrial genome of higher plants appears to be the largest known of any life form. Plant mitochondrial (mt) DNA displays substantial intermolecular heterogeneity with respect to size and physical organization. Electron microscopic studies reveal both linear and circular DNA molecules of varying size. Mapping data suggest that a circular master chromosome representing the entire sequence complexity of the genome gives rise to a series of discrete DNA molecules which are generated via recombination processes within certain repeats. Additionally to the large mtDNA, mitochondria of higher plants contain small plasmid-like DNAs behaving, at least in certain cases, like transpositional elements.

Plant mtDNA codes for 18S, 26S and 5S rRNAs and mitochondrial tRNAs as well as for at least 18–20 polypeptides, mainly membrane-bound components of the oxidative phosphorylation system.

Substantial evidence has been accumulated that cytoplasmic male sterility CMS, a maternally inherited trait is controlled by mtDNA. Male fertile and CMS cytoplasms differ in their mtDNA restriction patterns, in the polypeptides synthesized by their mitochondria, and in the appearance and distribution of the plasmid-like small mtDNAs.

• The culture of manually isolated heterokaryons ofNicotiana tabacum andNicotiana rustica

Protoplasts derived from leaf mesophyll tissue ofNicotiana tabacum were fused with cell suspension-derived protoplasts ofN. rustica. Heterokaryons were isolated using a micromanipulator and were cultured. Nuclear fusion was observed to occur in many of these heterokaryons after culturing them for a few days. Hybrid cell division was also observed. Fluorescein isothiocyanate (FITC) staining ofN. rustica protoplasts prior to fusion did not interfere with subsequent hybrid cell division, and theFITC fluorescence was observed to persist beyond the first division stage of hybrid cells. From a total of thirty heterokaryons which were placed in a nurse culture of protoplasts of albinoPetunia hybrida, thirteen green colonies were subsequently obtained of which six have regenerated somatic hybrid plants. Plants were characterised for their hybrid nature by analysis of vegetative and floral morphology, isoelectric focusing pattern of leaf esterases and Fraction 1 protein. All the six plants are nuclear hybrids. Chloroplast segregation appears to have occurred in these plants, with five having the Fraction 1 protein large subunit ofN. rustica, and one having the large subunit ofN. tabacum. Some of the plants possess sexual fertility.

• Eukaryotic transposable elements

Transposable elements first discovered in maize have been discovered subsequently also in bacteria, yeast,Drosophila, mammals etc. Structurally, eukaryotic transposable elements may be classified into two groups: ones with direct or inverse-repeat ends and the others with dAMP-rich sequence at one end. They generate direct repeats at the target site. Quite often, transposable elements are dispersed as a number of copies through the genome and at times may constitute a small but significant fraction. Their dispersal or transposition through the genome may involve excision (precise or imprecise), recombination (homologous or non-homologous) and replicative events in elements with direct or inverse repeats. dAMP-ended elements may move by reverse transcription. Maize elements can modulate gene action and yeast Tyl elements can enhance transcription. Nevertheless, evidence is not conclusive that transposable elements are involved in a major way in gene regulation and development. Structural similarities among yeast Tyl elements,Drosophila copia sequences and retroviral proviruses such as Rous sarcoma virus (RSV) and mouse mammary tumor virus (MMTV) suggest a formal possibility of horizontal transfers.

• Feulgen microspectrophotometric estimation of nuclear DNA of species and varieties of three different genera of Marantaceae

Karyological analysis including determination of somatic chromosome number, total chromosome length, volume and karyotype formula andin situ estimation of 4C-nuclear DNA amount were carried out on 14 different species and varieties of the generaCalathea, Maranta andStromanthe. The 4C nuclear DNA amount was estimated through Feulgen microspectrophotometry following single wavelength method and expressed in arbitrary units of relative absorbances. The variation in 4C DNA amounts between the species ofCalathea was not distinct but in two species ofMaranta, a notable variation in nuclear DNA amount was recorded. In addition, the amount of nuclear DNA did not show direct correlation with the total chromosome length and volume. The absence of wide difference in nuclear DNA content at an interspecific level might have some adaptive value.

• Nyctanthes is a member of the Oleaceae

The attributes ofNyctanthes (habit, floral morphology, fruit and seed, stem and leaf anatomy, flower vasculature, embryology, pollen, chromosome number and phytochemistry) are reviewed and found compatible with accommodation of the genus in the Oleaceae, tribe Jasmineae. The treatment ofNyctanthes in Verbenaceae or as a separate does not reflect its true affinities.

• Increasing plant productivity through improved photosynthesis

The importance of increasing plant productivity through photosynthetic route and relevance of higher chain aliphatic alcohols in promoting photosynthesis in plants, resulting in increased yields in various crops is discussed. A mixture of aliphatic alcohols (C-24 to C-34) designated as “Mixtalol” was prepared and tested as seed soak and foliar spray at 1–2 ppm. It was found that the treatment resulted in a significant increase in root length and number of laterals, shoot fresh weight and shoot and root dry weight of various crop plants. Mixtalol treatment as seed soaking of paddy increased the chlorophyll content of leaves, which was higher at younger stages of development. The seed soak and foliar spray of Mixtalol also increased Fe++ content of tomato and paddy shoots. It also significantly increased the rate of photosynthesis in tomato and paddy. In tomato and barley leaves, a simultaneous decrease in photorespiration rates was also observed.

Foliar application of individual alcohols, (components of Mixtalol) indicated that excepting for C-28, C-22 to C-30 increased the rate of photosynthesis. A mixture of C-24 to C-30, in the same proportion as that of Mixtalol, increased the rate of photosynthesis in paddy but Mixtalol registered a higher rate than the mixture, probably, because of the presence of still unidentified components in the mixture. Extensive field trials with Mixtalol, have shown yield increases of 14–27% in paddy, 13–27% in wheat, 33% in maize, 20% in pearl millet, 21–29% in potatoes, 15–20% in groundnuts and 48% in sorghum fodder. The foliar application of Mixtalol on vegetables (tomato, brinjal, okra, beans, cauliflower, chilli, etc.) gave substantial increases in yield.

• The science behind rotational bush fallow agriculture system (jhum)

Rotational bush fallow agriculture variously termed as shifting agriculture, slash and burn agriculture are commonly known in India asjhum is a traditional agricultural system of the humid tropics and is extensively practised by the tribes of the north-eastern hill region. There is a renewed interest in this agricultural system as it has so much to offer in terms of concepts and ideas to modern agricultural organization. The science behind jhum is based on intuitive experience of the farmer based on long tradition. This paper looks at the science behind jhum with particular emphasis on the ecological and economic significance of mixed cropping, recycling of resources within the system and between jhum and animal husbandry, the non-weed concept weed potential under different cycles of jhum, and nutrient cycling. The distortions brought about by the shortening of the jhum cycle to 4–5 yr is considered. Alternate strategies for development with jhum as the focal point, with suitable modifications but without the present-day distortions, have been considered.

• Forest tree improvement in India

Forest tree breeding is relatively a young science. Even so, there is good evidence of its potentiality for increasing forest productivity and quality of the forest produce. The basic scheme for forest tree improvement involves selection of superior parent trees, assembling them as clones in seed orchards in special designs to promote maximum cross pollination among the different clones and reduce inbreeding. Interprovenance and interspecific hybridisation are also resorted to in special situations. Forest tree improvement work through selection and breeding has been in progress in India for the last nearly two decades. Some of the achievements and strategies used are briefly reviewed.

• Some unusual features in the embryology of Angiosperms

Attention has been drawn to selected examples of unusual features in the embryology of angiosperms. The study of reproductive processes through microcinematography reveals sequential stages in living material which add a new dimension to our investigations. The unusually elongated embryo sacs inMoquiniella, synergid haustoria inCortaderia andQuinchamalium, aggressive invasion by chalazal endosperm haustorium in the pedicel inOlax andOpilia, zygotic mantle inAcrotrema, highly polyploid suspensor cells inPhaseolus, undifferentiated embryo inEriocaulon, and integumentary embryos in Compositae and Orchidaceae are briefly discussed. The association of bacteria with the flower and seed ofArdisia is essential for its perfect growth. Angiocarpy inTambourissa, intracarpellary pollen grains inButomopsis, and free-nuclear proembryo inPaeonia are typical gymnospermous characters in confirmed angiosperms.

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