Sandal Spike Disease Research Articles

A threat to sandalwood cultivation in the naturalised Marayoors andalwood reserve (Kerala, India) through single and mixed phytoplasma infections

The forest of Southern India, especially in the states of Karnataka, Tamil Nadu and Kerala are recognised for natural populations of sandalwood contributing 90% of its distribution in India. The sandal spike disease (SSD) of sandalwood is known to be associated with the presence of aster yellows (‘Candidatus Phytoplasma asteris’, 16SrI-B). The recent survey and collection of the symptomatic sandalwood samples from the Marayoor sandalwood reserve of Kerala state confirmed the presence of this phytoplasma; however, also 16SrXI-B phytoplasmas were identified. These phytoplasmas were present in single or in mixed infection in the collected sandalwood, sugarcane and Indian gooseberry samples from this area. This study is the first report of 16SrXI-B phytoplasmas in sugarcane in Kerala of witches’ broom disease in Indian gooseberry associated with aster yellows phytoplasmas and the first report of 16SrXI-B phytoplasma presence in SSD plants. These findings unveil serious threat to existing sandalwood and sugarcane cultivation in the Marayoor sandalwood reserve area, and demand a thorough investigation on phytoplasma insect vectors to efficiently manage these diseases associated with phytoplasmas.

Novel aster yellows phytoplasma subgroup associated with sandalwood spike disease in Kerala, India

The sandal spike disease of sandalwood is known to be associated with aster yellows (AY) phytoplasmas and is a prime threat to sandalwood cultivation in India. The Marayoor Sandalwood Reserve (Kerala state) has an excellent collection of naturalised and matured sandalwood trees and therefore sandalwood forest were surveyed and symptomatic samples were collected from this area. The study confirmed the disease association with AY phytoplasmas and allow to verify the presence of a novel AY phytoplasma strains indicating that phytoplasma strains are differentiating with their plant host species and geographic regions.

Santalum molecular biology: molecular markers for genetic diversity, phylogenetics and taxonomy, and genetic transformation

Species of the Santalum genus are well known for their fragrant hardwood, which has great value in medicinal, pharmaceutical and cosmetic industries. Sandalwood oil is derived from the heartwood of Santalum sp. and contains α-, β- and epi-β-santalols, which are responsible for its pleasant fragrance. Oil content can vary from species to species. Pressure on natural populations due to habitat loss, legal and illegal harvesting and disease is increasing. This paper highlights the development of molecular markers for the refinement of phylogenetic studies, identification of various Santalum and adulterant species, assessment of genetic diversity, genetic differentiation, clonality and management units within species, and for marker-assisted breeding. The identification of quantitative trait loci for sandal spike disease and for other traits such as specific rare secondary metabolites in the essential oil and related to its fragrance, would also benefit from molecular advances. RNA sequence analyses have already identified changes in gene expression and metabolic pathways in developing Santalum album L. haustoria.

Identification of a ‘Candidatus Phytoplasma asteris’‐related strain associated with spike disease of sandal (Santalum album) in India

Identification of a ‘<i>Candidatus</i> Phytoplasma asteris’‐related strain associated with spike disease of sandal (<i>Santalum album</i>) in India

Symptom remission in spiked sandal trees by infusion of tetracycline antibiotics

Spike disease of sandal has recently been recorded in Kerala. For chemotherapy of the diseased trees a gravity‐flow infusion technique was used to compare tetracycline compounds. All the compounds, including doxycycline and oxytetracycline, were effective when 500 mg per tree was infused in 500 ml water, but disease remission lasted for 4 months only. Repeated infusions failed to give complete remission. Increasing the concentration of tetracycline to 4–8 g per tree gave remission for 7–8 months; at 12 g per tree, phototoxicity was observed.

Mycoplasma and allied diseases of forest trees in India and vector-host-pathogen interactions

Mycoplasma and allied diseases of forest trees in India have been described,mlo disease has been intensively studied in ‘sandal’ (Santalum album L.). Other forest trees showing typicalmlo etiology are ‘toon’(Toona ciliata), Acacia catechu, A. mearnsii, Eucalyptus grandis andE. tereticornis. Disease symptoms, collateral hosts, transmission tests with possible insect vectors and vector biology have been described for sandal spike disease. Reasons for contradictory results for sandal spike vectors have been discussed and possible lines of vector search for woody plants are described. Vector-host-pathogen interactions have been reviewed. During the feeding process, phloem cells are punctured, torn and disturbed by vectors. The hypertrophy of the plant cells around the site of puncture is caused by the action of injected salivary secretion. Vector borne procaryotic disease pathogens multiply within the vectors and circulate through a sequence of tissues and organs of vectors when the latent period of pathogen is long. These initiate both harmful and beneficial interactions within the vector. Possible lines of research to fill up the existing lucunae for insect vectors of mycoplasma and allied diseases of forest trees and vector-host-pathogen interactions have been discussed.

Insect vectors of sandal spike disease

AbstractA review of present status of knowledge in respect of insect vectors of sandal spike disease in India has been given. So far, three species of homopterous insects, namely, Moonia albimaculata, Coelidea indica and Nephotettix virescens, have been incriminated as possible vectors of spike disease of sandal. The experimental methods used for the transmission tests have been discussed. Except Nephotettix virescens, the role of remaining two species needs further investigation.Conclusion: From the account given above, it seems likely that more than one species of leaf‐hoppers are involved in spreading the disease in nature (Sen‐Sarma 1981). Currently leaf‐hopper species occurring in sandal ecosystem are being screened for their ability to transmit the disease.ZusammenfassungInsekten als Vektoren bei der “Sandal‐Spike‐Krankheit”Es wird ein Überblick über den gegenwärtigen Wissensstand zur Frage der Insekten als Vektoren bei der “Sandal‐Spike‐Krankheit” gegeben. Bis jetzt werden die drei Homopteren‐Arten Moonia albimaculata, Coelidea indica und Nephotettix virescens als mögliche Vektoren von “Sandal‐Spike” angesehen. Die experimentellen Methoden für die Transmissionsversuche werden diskutiert. Mit Ausnahme von N. virescens bedarf die Vektorfunktion der beiden anderen Arten weiterer Untersuchungen.RésuméInsectes vecteurs de la maladie épineuse du SantalUne revue de l'état actuel des connaissances pour ce qui concerne les insectes vecteurs de la maladie épineuse du Santal en Inde est fournie. Ainsi trois espèces d'Homoptères nommés respectivement Moonia albimaculata, Coelidea indica et Nephotettix virescens ont été mis en cause en tant que vecteurs possibles de la maladie épineuse du Santal. Les méthodes expérimentales utilisées pour les essais de transmission on fait l'objet de discussion. A l'exception du Nephotettix virescens, le rǒle des deux autres espèces nécessite une recherche plus poussée.

Control of spike disease of sandal

AbstractIn the natural sandal reserves arsenic compounds have not proved successful in erradicating the spike disease; benlate has no curative or remission effect; tetracyclines have remission effects but application is not practical in forests due to the low density of sandal per hectare and difficulty in locating diseased trees. Compounds tried by various workers have provided no cure in the field. As vegetative propagation in sandal has not been successful, heat therapy also cannot be taken up. Eucalyptus has failed to control spike. But encouraging results have been obtained in checking the incidence of spike in man made forests by soil working, use of cover crop, interplanting sandal with trees giving shade at different levels, thus reducing the loss of water by evapotranspiration. In the natural reserves where the above conditions are prevalent spike disease has not been reported for the last 80 years.

Sandal spike disease and its possible control

The symptoms and economic background of Sandal spike, a dieback of mycoplasmal origin of Santalum album, are described. Successful trials of various chemicals to control the disease are reported.

Light and electron microscopy of Vinca plants infected with mycoplasma-like bodies of the sandal spike disease

Light and electron microscopy of Vinca plants infected with mycoplasma-like bodies of the sandal spike disease

Light and electron microscopy of Vinca plants infected with mycoplasma-like bodies of the sandal spike disease

Detection of phloem cells containing mycoplasma-like bodies associated with the sandal spike disease was made easier by observing sections from stems of infectedVinca rosea plants by means of fluorescence microscopy. The aniline blue-stained cells that contained mycoplasma-like bodies fluoresced yellow in ultraviolet light (366 nm). The presence of mycoplasma-like bodies was confirmed by examination of ultrathin sections obtained from the same stems in the electron microscope.

An anomalous form of mycoplasma-like bodies in periwinkle infected with the sandal spike agent

An anomalous form of mycoplasma-like bodies was found in ‘necrotic’ cells in the sieve elements of periwinkle stem after infection with the sandal spike disease agent. These bodies, 50–160 nm in diameter, were strongly osmiophilic and bounded by a unit membrane. It is suggested that these anomalous bodies represent a naturally degenerated form of the mycoplasma-like bodies.

Transmission by dodder of sandal spike disease and the accompanying mycoplasma-like organisms via Vinca rosea

HealthyVinca rosea plants, connected by dodder strands with spike-diseased sandal trees developed witches' broom symptoms. Electron microscopy of petioles of the infectedVinca plants revealed the presence of numerous mycoplasma-like bodies. Fresh dodder established on theVinca plants with witches' broom symptoms and trained onto healthy sandal trees, transmitted the spike disease back to the latter. De ‘spike’-ziekte van de sandelboom (Santalum album) behoort tot de heksenbezemziekten. Zoals eerder werd aangetoond bevatten door deze ziekte aangetaste sandelbomen mycoplasma-achtige lichaampjes in het floeem van takken en bladeren. Daar alleen met zekerheid bekend is dat de ziekte door enting op gezonde sandelbomen kan worden overgebracht, is nagegaan of met behulp van warkruid (Cuscuta subinclusa) andere plantesoorten konden worden geinfecteerd. Vijf tot tien weken nadat zich op gezonde planten vanVinca rosea utilopers van het warkruid, afkomstig van ‘spike’-zieke sandelbomen hadden gehecht, hielden deVinca-planten op met bloeien en vertoonden de bladeren nerfglazigheid en tussennervige chlorose; op sommige planten werd eveneens fyllodie waargenomen. Enige tijd later ontwikkelden zich aan scheuten van uitgelopen okselknoppen kleine, smalle, geelgroene blaadjes (Fig. 1). Na ongeveer 16–20 weken verwelkten deVinca-planten en stierven af. Werden oudere planten geinfecteerd dan bestonden de heksenbezemsymptomen hoofdzakelijk uit fyllodie, apicale rozetten en lichte bladvergeling (Fig. 2). Door opnieuw warkruid te laten groeien op de ziek gewordenVinca-planten en uitlopers van de parasiet te leiden naar gezonde sandelbomen verschenen ongeveer 16 weken nadat het warkruid zich op laatstgenoemde had gehecht typische ‘spike’-symptomen op een van de twee bomen (Fig. 3). Elektronenmicroscopisch onderzoek van bladsteeltjes van vergeeldeVinca-blaadjes gaf een groot aantal mycoplasma-achtige lichaampjes van verschillende vorm en afmeting te zien (Fig. 4 en 5). Hiermee is aangetoond, dat de ‘spike’-ziekte van de sandelboom door warkruid kan worden overgebracht opVinca rosea en weer terup op sandel en dat ook inVinca de symptomen samengaan met het voorkomen van mycoplasma-achtige lichaampjes.

Mycoplasma-like Bodies associated with Sandal Spike Disease

SPIKE disease of Sandal (Santalum album L.) is of considerable importance to the sandal-wood industry of southern India1,2. It has been considered for many years that this disease is caused by a virus3 and its transmission by grafting3,4, by haustoria of sandal3, by the leafhopper Jassus indicus (Walk)5 and by sap inoculation6 has been reported. Sandal spike disease has several symptoms7 which resemble those of the “yellows” group of plant diseases: there is a reduction in leaf size, loss of apical dominance of the branches giving a “witches-broom” condition and phyllody of the flowers. Because many of the “yellows” group of diseases are now attributed to infection by mycoplasma-like organisms8–17, spike-infected sandal was examined for the presence of such bodies. This communication reports the presence of mycoplasma-like structures associated with sandal spike infection and compares their morphology with known mycoplasmas.

Spike Disease of Sandal

THE spike disease of sandal was first noticed forty years ago and since then numerous investigators have studied the problem. For the most recent account of the disease the reader is referred to an article by Rao Sahib S. R. Iyengar and A. L. Griffith (Indian Forest Records, 6, No. 4).

Physiology of the spike disease of sandal

The study of physiological characteristics of virus diseases will be found useful in (1) diagnosing the disease at an early stage and (2) in discovering resistant strains. Such studies have hardly been begun with sandal. Holmes (1932) has recently developed a technique of iodine staining which renders local lesions, due to virus, conspicuous and reveals the points of infection. Such studies may be profitably extended to sandal spike. Resistant varieties are generally characterised by low acidity and poor oxidase activities. Other factors of disease resistance, such, for instance as, phenols, glocosides, alkaloids, etc., have to be investigated. The study of active groups in tissue fluids for which a scheme was recently outlined (Sastri and Sreenivasaya, 1934) may usefully be undertaken in this connection. The possibility of nurturing sandal through appropriate hosts to impart resistance to disease has been amply demonstrated by the work of Sreenivasaya and the study of physiological characters of such plants would give results of great significance.

Field studies in the spike-disease of sandal (Santalum album Linn)

Field studies in the spike-disease of sandal (Santalum album Linn)

Spike Disease in Sandal

SANDAL has long been a valuable forestry product in southern India and the mysterious disease termed ‘spike’ has been the subject of investigation during the past quarter of a century. Various bodies interested in sandal are collaborating, such as the Madras Forest Department, the Indian Institute of Science at Bangalore, the Forest Research Institute at Dehra Dun and others. A report on the progress made during the half-year ending September 30, 1932, entitled “Investigations on the Spike-Disease of Sandal” has been issued by the Institute of Science, Bangalore. The sporadic attacks of this pest have a strange parallel to those of foot and mouth disease in Great Britain. A recrudescence of the disease in an epidemic form has been noticed in the Beedamaruthupatti spike area. Pollarding, which has been carried out on a fairly large scale in the Galigattam and Manchi areas, has yielded significant data. So far, Manchi has the maximum percentage of disease-masking sandal plants. The entire freedom from infection of a few areas, Sanamavu and Thalli in North Salem and Chickabettakere in Coorg, has been established by pollarding. More detailed technical contributions will appear as scientific papers in the Journal of the Indian Institute of Science, Dehra Dun Forest Research Publications, and elsewhere. Meanwhile it is a valuable departure to issue progress reports so that the various investigators studying the pest, which causes so heavy a financial loss, should have early news of any results achieved.

Spike Disease in Indian Sandal

AN editorial article in the September number of the Indian Forester (vol. 43) deals with progress in forestry research. The writer commences by directing attention to the report of the seventh Spike Conference (reproduced in this number). It is more than thirty years since the first attempts to study the spike disease of sandal were made. Sandal is one of the major forest products throughout southern India, and the value of the trade in this precious timber amounts to 30–40 lakhs of rupees annually, apart from the market value of the sandalwood oil. Most of the sandal-bearing forests are affected by the spike disease, the presence of which reduces the sandal output by about half, and in many places has killed out valuable crops. So far, in spite of the close study made, no cure has been found and the issue is complicated owing to the sandal being itself a parasite and unable to flourish without some other tree species as a host. The various governments affected have combined in the research work which is now being conducted on an intensive scale. Spike disease of sandal is but one out of many problems which await the investigator in Indian forest research. The Government forest estate alone covers an area of 160,000,000 acres; the forest area in the Indian States covers 45,000,000 acres; whilst in addition there is an even larger area of private and village forest lands. Probably about half of the 160 million acres of forests under the control of the Indian Forest Department are commercially productive, the other half being conserved for the use of right holders or serving as purely ‘protection forests’. In spite of this, the revenue has risen from 70 lakhs (a surplus of 17 lakhs) in 1870 to 6 crores of rupees (surplus 2½ crores) in 1930. Research has, so far, cost Rs. 3.6 per square mile, as against a surplus of Rs. 105 per square mile.

Biochemical Studies of Spike Disease of Sandal

MR. M. SREENIVASAYA and Mr. B. N. Sastri have continued their very detailed investigations into the spike disease of sandal (Santalum album L), and their latest results are to be found in the Journal of the Indian Institute of Science, vol. 12A, Part 17, pp. 233 to 252 (1929). Leaf-juice from a sandal tree infected with the spike disease hydrolyses more soluble starch than does the corresponding healthy juice. This is due to a higher concentration of the enzyme and to the presence of activators such as phosphates and amino acids. The pH of spiked leaves is lower than that of healthy leaves, and approaches the optimum for diastatic activity. More potato starch is, however, liquefied by the healthy leaf extract than by the diseased extract for equal weights of sugar produced, thus suggesting a qualitative difference between the two diastase extracts. It should be remembered that Dr. L. C. Coleman found that there was lower diastatic activity in spiked leaves than in healthy leaves, and therefore the results here reported might be interpreted as showing that the diastase content of diseased tissue fluctuates within the same limits as does that of healthy tissue.