Sugarcane grassy shoot disease (SCGS), is associated with ‘ ''Candidatus'' Phytoplasma sacchari’ which are small, pleomorphic,

pathogenic In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

bacteria that contributes to yield losses from 5% up to 20% in

sugarcane Sugarcane or sugar cane is a species of (often hybrid) tall, Perennial plant, perennial grass (in the genus ''Saccharum'', tribe Andropogoneae) that is used for sugar Sugar industry, production. The plants are 2–6 m (6–20 ft) tall with ...

. These losses are higher in the ratoon crop. A higher incidence of SCGS has been recorded in some parts of

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...

and

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

, resulting in 100% loss in cane yield and

sugar Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double ...

production.

SCGS disease symptoms

Phytoplasma-infected sugarcane plants show a proliferation of tillers, which give it typical grassy appearance, hence the name grassy shoot disease. The leaves of infected plants do not produce

chlorophyll Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll allow plants to a ...

, and therefore appear white or creamy yellow. The leaf veins turn white first as the phytoplasma resides in leaf phloem tissue. Symptoms at the early stage of the plant life cycle include leaf

chlorosis In botany, chlorosis is a condition in which leaves produce insufficient chlorophyll. As chlorophyll is responsible for the green color of leaves, chlorotic leaves are pale, yellow, or yellow-white. The affected plant has little or no ability to ...

, mainly at the central leaf whorl. Infected plants do not have the capacity to produce food in the absence of

, which results in no cane formation. These symptoms can be seen prominently in the stubble crop. The eye or

lateral bud The axillary bud (or lateral bud) is an embryonic or organogenic shoot located in the axil of a leaf. Each bud has the potential to form shoots, and may be specialized in producing either vegetative shoots (stems and branches) or reproductive sh ...

s sprout before the normal time on growing cane. A survey of various fields of western

Maharashtra Maharashtra (; , abbr. MH or Maha) is a states and union territories of India, state in the western India, western peninsular region of India occupying a substantial portion of the Deccan Plateau. Maharashtra is the List of states and union te ...

showed grassy shoot with chlorotic or creamy white leaves was the most prevalent phenotype in sugarcane plants infected with SCGS.

Causal organism

SCGS

disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

is related to a

Phytoplasma Phytoplasmas are obligate intracellular parasites of plant phloem tissue and of the insect vectors that are involved in their plant-to-plant transmission. Phytoplasmas were discovered in 1967 by Japanese scientists who termed them mycoplasma-lik ...

‘ ''Candidatus'' Phytoplasma sacchari’ Kirdat K, Tiwarekar B, Thorat V, Sathe S, Shouche Y, Yadav A. 'Candidatus Phytoplasma sacchari', a novel taxon - associated with Sugarcane Grassy Shoot (SCGS) disease. Int J Syst Evol Microbiol. Dec 8. 2020. Epub ahead of print. . oi: 10.1099/ijsem.0.004591/ref>), which is one of the destructive

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

s of

(''Saccharum officinarum L''). In

, SCGS phytoplasmas are spreading at an alarming rate, adversely affecting the yield of the sugarcane crop.Nasare, K., Yadav, Amit., Singh, A. K., Shivasharanappa, K. B., Nerkar, Y. S., and Reddy, V. S. Molecular and symptom analysis reveal the presence of new phytoplasmas associated with sugarcane grassy shoot disease in India. (2007). Plant Disease. 91:1413-141

Rao, G. P. and Ford, R. E. (2000) Vectors of virus and Phytoplasma diseases of Sugarcane: An Overview. In: Sugarcane Pathology, Vol. III. Virus and Phytoplasma diseases, G.P. Rao, R.E. Ford, M. Tosic and D.S. Teakle (Eds) Science Publishers, Hamshere, USA, Pg: 265-314.Rao, G. P. and Dhumal, K. N. (2002) Grassy Shoot Disease of Sugarcane. In: Sugarcane Crop Management by Singh S., Rao G. and Easwatnamoorthy S. SCI TECH Publications, USA. Pg. 208-222. Phytoplasmas formerly called

mycoplasma ''Mycoplasma'' is a genus of bacteria that, like the other members of the class ''Mollicutes'', lack a cell wall around their cell membranes. Peptidoglycan (murein) is absent. This characteristic makes them naturally resistant to antibiotics ...

-like organisms (

MLOs Phytoplasmas are obligate intracellular parasites of plant phloem tissue and of the insect vectors that are involved in their plant-to-plant transmission. Phytoplasmas were discovered in 1967 by Japanese scientists who termed them mycoplasma-li ...

), are a large group of obligate, intracellular, cell wallless parasites classified within the class

Mollicute Mollicutes is a class of bacteria distinguished by the absence of a cell wall. The word "Mollicutes" is derived from the Latin ''mollis'' (meaning "soft" or "pliable"), and ''cutis'' (meaning "skin"). Individuals are very small, typically only 0 ...

s. Phytoplasmas are associated with plant diseases and are known to cause more than 600 diseases in several hundred plant species, including gramineous

weed A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...

s and

cereals A cereal is any grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, germ, and bran. Cereal grain crops are grown in greater quantities and provide more food en ...

.Lee, I. M., Davis, R. E., and Gundersen-Rindal, D.E. (2000) Phytoplasma: Phytopathogenic mollicutes. Annu. Rev. Microbiol. 54: 221-255.Lee, I. M., Davis, R. E., and Gundersen-Rindal, D.E. and Bertaccini A. (1998) Phytoplasma: Ecology and Genomic Diversity. Phytopathology. 88:1359-1366.Lee, I.M., Hammond, R.W., Davis, R.E. and Gunderson D.E. (1993) Universal amplification and analysis of pathogen 16SrDNA for classification and Identification of Mycoplasma like Organisms. Molecular Plant Pathol. 83(8): 834-842. The symptoms shown by infected

plants Plants are predominantly Photosynthesis, photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all curr ...

include: whitening or yellowing of the

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

, shortening of the

internodes A stem is one of two main structural axes of a vascular plant, the other being the root. It supports leaves, flowers and fruits, transports water and dissolved substances between the roots and the shoots in the xylem and phloem, stores nutrien ...

(leading to stunted growth), smaller leaves and excessive proliferation of shoots, resulting in a broom

phenotype In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological proper ...

and loss of

apical Apical means "pertaining to an apex". It may refer to: *Apical ancestor, refers to the last common ancestor of an entire group, such as a species (biology) or a clan (anthropology) *Apical (anatomy), an anatomical term of location for features loc ...

dominance.

Transmission

Sugarcane is a vegetatively propagated crop, so the pathogen is transmitted via

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...

material and by

phloem Phloem (, ) is the living biological tissue, tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose, to the rest of the plant. This tran ...

-feeding

leafhopper A leafhopper is the common name for any species from the family Cicadellidae. These minute insects, colloquially known as hoppers, are plant feeders that suck plant sap from grass, shrubs, or trees. Their hind legs are modified for jumping, and a ...

vectors.Shomi, T. and Sugiura, M. Grouping of mycoplasma-like organisms transmitted by the leafhopper vector, Macrosteles orientalis Virvaste, based on host range. (1984). Ann. Phytopatholol. Soc. Jpn. 50: 149-157.Kavakita, H., Saiki, T., Mitsuhashi, W., Watanabe, K. and Sato, M. (2000) Identification of Mulberry Dwarf Phytoplasma in the genital and eggs of leafhopper Hishimonoides sellatiformis. Bateriology. 90: 909-914. '' Saccharosydne saccharivora'',Arocha, Y., Lopez, M., Fernandez, B., Pinol, D., Horta, D., Peralta, R., Almeida O., Picornell, S., Wilson, M and Jones P (2005) Transmission of a Sugarcane Yellow Leaf Phytoplasma by the Delphacid Plant hopper Saccharosydne saccharivora, a new vector of sugarcane yellow leaf syndrome. Plant Pathology. 54: 634-642. '' Matsumuratettix hiroglyphicus'',SHanboonsong Y., Choosai C., Panyim S. and Damak S. (2002). Transovarial transmission of sugarcane white leaf phytoplasma in the insect vector Matsumuratettix hiroglyphicus (Matsumura). Insect Molecular Biology. 11(1): 97–103 ''

Deltocephalus vulgaris ''Deltocephalus'' is a leafhopper genus in the sub family Deltocephalinae.Review of the ''Deltocephalus'' group of leafhoppers (Hemiptera: Cicadellidae: Deltocephalinae) in China. Zhang Y and Duan Y Zootaxa, 2011, 2870, pages 1–47 Preview '' De ...

''Srivastava, S., Singh, V., Gupta, P. S., Sinha O. K., and Baitha, A. Nested PCR assay for detection of sugarcane grassy shoot phytoplasma in the leafhopper vector Deltocephalus vulgaris the first report. (2006). Plant Pathol. 22:25-28. and '' Yamatotettix flavovittatus''HANBOONSONG Y., RITTHISON W., CHOOSAI C., SIRITHORN P. Transmission of sugarcane white leaf phytoplasma by Yamatotettix flavovittatus, a new leafhopper vector (2006). Journal of Economic Entomology. 99(5):1531-1537. ISSN 0022-0493 have been confirmed as vectors for phytoplasma transmission in sugarcane. Unconfirmed reports also suggest a spread through the steel blades (

machete Older machete from Latin America Gerber machete/saw combo Agustín Cruz Tinoco of San Agustín de las Juntas, Oaxaca">San_Agustín_de_las_Juntas.html" ;"title="Agustín Cruz Tinoco of San Agustín de las Juntas">Agustín Cruz Tinoco of San ...

s) used for sugarcane harvesting..

Detection

Phytoplasma-infected sugarcane can be recognized by visual symptoms, but there are limitations. Visual symptoms occur only after considerable growth, normally two to three weeks after planting. If not observed keenly, confusion may occur on differences between symptoms of SCGS disease and iron deficiency. In addition to above points, the poor relationship between symptoms and phytoplasma presence has been confirmed by earlier findings that symptoms alone are not reliable indicators of infection or identity. This highlights the importance of employing tests, such as molecular tests, to verify associations between phytoplasma and putative disease symptoms. Also, it suggests the inability to recognize symptomless sugarcane harbouring a phytoplasma could result in inadvertent exposure of sugarcane to a potential disease source.Blanche, K. R., Tran-Nguyen, T. T., and Gibb, K. S. 2003. Detection, identification and significance of phytoplasmas in grasses in northern Australia. Plant Pathol. 52:505-512. Precise

diagnosis Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic, analytics, and experience, to determine " cause and effect". In systems engin ...

is, therefore, necessary for effective disease identification and control. Though reliable, DNA hybridization,Webb, D.R., Bonfiglioli, R.G., Carraro, L., Osler, R. and Symons, R.H. Oligonucleotide as Hybridization probes to Localize Phytoplasmas in Host Plants and Insect Vectors. (1998). Phytopathology. 89: 894-901.

electron microscopy An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a hi ...

and PCR techniques require specialized equipment and trained

human resource Human resources (HR) is the set of people who make up the workforce of an organization, business sector, industry, or economy. A narrower concept is human capital, the knowledge and skills which the individuals command. Similar terms include m ...

s. Among these, PCR is an accurate, economical and convenient method, which allows analysis of samples in a short time. In recent years, regions of the

rRNA Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from ribosoma ...

operon In genetics, an operon is a functioning unit of DNA containing a cluster of genes under the control of a single promoter. The genes are transcribed together into an mRNA strand and either translated together in the cytoplasm, or undergo splic ...

of the

prokaryotic A prokaryote () is a Unicellular organism, single-celled organism that lacks a cell nucleus, nucleus and other membrane-bound organelles. The word ''prokaryote'' comes from the Greek language, Greek wikt:πρό#Ancient Greek, πρό (, 'before') a ...

and

eukaryotic Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

organisms have been

sequenced In genetics and biochemistry, sequencing means to determine the primary structure (sometimes incorrectly called the primary sequence) of an unbranched biopolymer. Sequencing results in a symbolic linear depiction known as a sequence which suc ...

and are being used to develop PCR-based detection

assays An assay is an investigative (analytic) procedure in laboratory medicine, mining, pharmacology, environmental biology and molecular biology for qualitatively assessing or quantitatively measuring the presence, amount, or functional activity of a ...

. These sequences are highly specific to the infecting

organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...

. The

ribosomal DNA Ribosomal DNA (rDNA) is a DNA sequence that codes for ribosomal RNA. These sequences regulate transcription initiation and amplification, and contain both transcribed and non-transcribed spacer segments. In the human genome there are 5 chromos ...

contains one transcriptional unit with a

cluster may refer to: Science and technology Astronomy * Cluster (spacecraft), constellation of four European Space Agency spacecraft * Asteroid cluster, a small asteroid family * Cluster II (spacecraft), a European Space Agency mission to study t ...

genes In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

coding for the 18S, 5.8S and

28S 28S ribosomal RNA is the structural ribosomal RNA (rRNA) for the LSU rRNA, large subunit (LSU) of eukaryotic cytoplasmic ribosomes, and thus one of the basic components of all eukaryotic cells. It has a size of 25S in plants and 28S in mammals, ...

s and two internal transcribed spacer regions,

ITS1 Internal transcribed spacer (ITS) is the spacer DNA situated between the small-subunit ribosomal RNA (rRNA) and large-subunit rRNA genes in the chromosome or the corresponding transcribed region in the polycistronic rRNA precursor transcript. I ...

and ITS2White, T. J., T. Bruns, S. Lee, and J. W. Taylor. (1990). Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. In: PCR Protocols: A Guide to Methods and Applications, eds. Innis, M. A., D. H. Gelfand, J. J. Sninsky, and T. J. White. Academic Press, Inc., New York. Pp. 315-322. in eukaryotes, and for 16S, 5S and 23S in prokaryotes . Previous studies have demonstrated the complex ITS regions are useful in measuring close

genealogical Genealogy () is the study of families, family history, and the tracing of their lineages. Genealogists use oral interviews, historical records, genetic analysis, and other records to obtain information about a family and to demonstrate kinsh ...

relationships because they exhibit greater interspecies differences than the smaller and larger subunits of rRNA genes. The use of specific probes as selective PCR primers offers an impressive approach for the rapid identification of a large number of phytoplasma

isolates {{About, , the linguistics term dealing with languages unrelated to any other language in the world, Language isolate, other uses, Isolate (disambiguation){{!Isolate Isolates is a term used in developmental psychology and family studies, to describ ...

.Smart, C. D., Schneider, B., Blomquist, C., Guerra, L. J., Harrison, N. A., Ahrens, U., Lorenz, K. H., Seemüller, E., and Kirkpatrick, B. C. Identification of phytoplasma strain-specific PCR primers obtained from 16S/23S rRNA spacer sequences. (1996). Appl. Environ. Microbiol. 62: 2988-2993.Namba, S., Kato S., Iwanami, S., Oyaizu, H., Shizawa, H. and Tsuchizaki, T. (1993) Detection and differentiation of Plant-Pathogenic Mycoplasma like organisms using

Polymerase chain reaction The polymerase chain reaction (PCR) is a method widely used to rapidly make millions to billions of copies (complete or partial) of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it (or a part of it) t ...

. Phytopathology. 83: 786-791.Ahrens, U., and Seemüller, E. (1992) Detection of DNA of plant pathogenic mycoplasma-like organisms by a polymerase chain reaction that amplifies a sequence of the 16S rRNA gene. Phytopathology. 82:828-832.Gundersen, D., Lee, I. M., Rehner, S., Davis, R. and Kingsbury D. (1994) Phylogeny of Mycoplasmalike organisms (Phytoplasmas): a basis for their classification. Journal of Bacteriology. 176: 5244-5254. Amit Yadav SID P 033

Control

In SCGS disease, the primary concern is to prevent the disease rather than treat it. Large numbers of phytoplasma-infected seed sets used by the farmers usually cause fast SCGS disease spread. Healthy, certified 'disease-free' sugarcane sets are suggested as planting material. If disease symptoms are visible within two weeks after planting, such plants can be replaced by healthy plants. Uprooted infected sugarcane plants need to disposed of by burning them. Moist hot air treatment of sets is suggested to control infectionVishwanathan, R. Grassy shoot. In: A Guide to Sugarcane Diseases. P. Rott, R.A. Bailey, J.C. Comstock, B.J. Croft and A.S. Saumtally, (Eds) France: CIRAD ISSCT. (2000). Pg: 215-220. before planting. This reduces the percentage of

disease incidence In epidemiology, incidence is a measure of the probability of occurrence of a given medical condition in a population within a specified period of time. Although sometimes loosely expressed simply as the number of new cases during some time peri ...

, but causes a reduction in the percentage of bud sprouting. Reports that the disease spreads through steel blades used for sugarcane harvesting are unconfirmed, but treating the knives using a disinfectant (

Lysol Lysol (; spelled Lizol in India) is a brand of American cleaning and disinfecting products distributed by Reckitt, which markets the similar Dettol or Sagrotan in other markets. The line includes liquid solutions for hard and soft surfaces, ai ...

) or by dipping them in boiling water for some time is suggested as a precaution. Phytoplasma infection also spreads through

insect vectors In epidemiology, a disease vector is any living agent that carries and transmits an infectious pathogen to another living organism; agents regarded as vectors are organisms, such as parasites or microbes. The first major discovery of a disease vec ...

; it is, therefore, important to control them. General field observation reports the ratoon crop has a higher percentage of disease incidence than the initial planted (main) crop. When the disease incidence is more than 20%, it is suggested to discontinue that crop cycle. It is always wise to purchase the certified planting material from authorized seed growers, which assures disease-free planting material.

Sugarcane Iron Deficiency and SCGS Disease

Symptoms of

iron deficiency Iron deficiency, or sideropenia, is the state in which a body lacks enough iron to supply its needs. Iron is present in all cells in the human body and has several vital functions, such as carrying oxygen to the tissues from the lungs as a key ...

(interveinal chlorosis) are very similar to those of SCGS. It shows creamy leaves, but no

occurs in leaf veins, and they remain green. In the case of severe iron deficiency, veins may lose chlorophyll in the absence of

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...

and appear similar to SCGS disease.Dametie, T. Mamo, A. Zelleke (1995) Studies on Iron Chlorosis of Sugar Cane (Saccharum officinarum L.) at Metahara, Ethiopia: Soil and Plant Characterisation and Efficiency of Different Iron Sources. Journal of Agronomy and Crop Science 175 (5), 317-324.Pal R., D. P. Motiramani, S. B. Gupta, and B. S. Bhargava (1990). Chlorosis in sugarcane: Associated soil properties, leaf mineral composition, and crop response to iron and manganese. Journal Nutrient Cycling in Agroecosystems 22 (3) 129-136. Iron deficiency is caused by a lack of

nutrients in the soil; therefore, one may observe several plants showing symptoms of iron deficiency in localized patches in a field. Phytoplasma-infected plants, though, may occur anywhere in the field in a more random distribution. Treatment with 0.1%

ferrous sulfate Iron(II) sulfate (British English: iron(II) sulphate) or ferrous sulfate denotes a range of salts with the formula Fe SO4·''x''H2O. These compounds exist most commonly as the hepta hydrate (''x'' = 7) but several values for x are kno ...

, either by spraying or supplying it through

fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...

cures iron deficiency, but phytoplasma-infected sugarcane does not respond to any treatment. Phytoplasma-infected plants growing ''

in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology an ...

'' show sensitivity to

tetracycline Tetracycline, sold under various brand names, is an oral antibiotic in the tetracyclines family of medications, used to treat a number of infections, including Acne vulgaris, acne, cholera, brucellosis, plague (disease), plague, malaria, and sy ...

References

External links

Sugarcane India growth statistics details figures

List of Sugarcane Diseases

Diseases of Sugarcane(Saccharum spp. hybrids

Common Names of sugarcane diseases and their causal agents

Diseases in Sugarcane (Sugarcane Handbook)