''Rotylenchulus reniformis'', the reniform nematode, is a species of

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...

of plants with a worldwide distribution in the

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

and

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...

regions.Ferris, H
''Rotylenchulus reniformis''.
Nemaplex. Department of Nematology. University of California, Davis. 2012.

Taxonomy

This nematode has a wide host range, infecting many species of plants around the world. It was first observed on the roots of

cowpea The cowpea (''Vigna unguiculata'') is an annual herbaceous legume from the genus '' Vigna''. Its tolerance for sandy soil and low rainfall have made it an important crop in the semiarid regions across Africa and Asia. It requires very few inpu ...

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

, and was described as new species and new genus in 1940.Robinson, A. F., et al. 1997
''Rotylenchulus'' species: identification, distribution, host ranges, and crop plant resistance.
''Nematropica'' 27(2), 127-80. Its

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

, ''reniformis'', was inspired by the

kidney In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...

shape of the adult female. There are now ten species classified in the genus, but ''R. reniformis'' is the only species of major economic importance to agriculture. Recent studies have demonstrated '' R. macrosoma'' is the

sister species In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to ''R. reniformis.''

Distribution and host range

''R. reniformis'' has been reported from thousands of localities in the Americas, Africa, Europe, Asia, and Australia.Wang, K
Reniform Nematode, ''Rotylenchulus reniformis'' Linford and Oliveira (Nematoda: Tylenchida: Tylenchoidea: Hoplolaimidae: Rotylenchulinae).
EENY-210 (IN367). Entomology and Nematology. Florida Cooperative Extension Service. University of Florida IFAS. Published 2001, revised 2007. It has a wide host range that includes fruit trees,

lentil The lentil (''Vicia lens'' or ''Lens culinaris'') is an annual plant, annual legume grown for its Lens (geometry), lens-shaped edible seeds or ''pulses'', also called ''lentils''. It is about tall, and the seeds grow in Legume, pods, usually w ...

cotton Cotton (), first recorded in ancient India, is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure ...

pigeon pea The pigeon pea (''Cajanus cajan'') or toor dal is a perennial legume from the family (biology), family Fabaceae native to the Eastern Hemisphere. The pigeon pea is widely cultivated in tropical and semitropical regions around the world, being com ...

tea Tea is an aromatic beverage prepared by pouring hot or boiling water over cured or fresh leaves of '' Camellia sinensis'', an evergreen shrub native to East Asia which probably originated in the borderlands of south-western China and nor ...

tobacco Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...

soybean The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean. Soy is a staple crop, the world's most grown legume, and an important animal feed. Soy is a key source o ...

pineapple The pineapple (''Ananas comosus'') is a Tropical vegetation, tropical plant with an edible fruit; it is the most economically significant plant in the family Bromeliaceae. The pineapple is indigenous to South America, where it has been culti ...

banana A banana is an elongated, edible fruit – botanically a berry – produced by several kinds of large treelike herbaceous flowering plants in the genus '' Musa''. In some countries, cooking bananas are called plantains, distinguishing the ...

okra Okra (, ), ''Abelmoschus esculentus'', known in some English-speaking countries as lady's fingers, is a flowering plant in the Malvaceae, mallow family native to East Africa. Cultivated in tropical, subtropical, and warm temperate regions aro ...

coconut The coconut tree (''Cocos nucifera'') is a member of the palm tree family (biology), family (Arecaceae) and the only living species of the genus ''Cocos''. The term "coconut" (or the archaic "cocoanut") can refer to the whole coconut palm, ...

cabbage Cabbage, comprising several cultivars of '' Brassica oleracea'', is a leafy green, red (purple), or white (pale green) biennial plant grown as an annual vegetable crop for its dense-leaved heads. It is descended from the wild cabbage ( ''B.& ...

sweet potato The sweet potato or sweetpotato (''Ipomoea batatas'') is a dicotyledonous plant in the morning glory family, Convolvulaceae. Its sizeable, starchy, sweet-tasting tuberous roots are used as a root vegetable, which is a staple food in parts of ...

alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial plant, perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, ...

corn Maize (; ''Zea mays''), also known as corn in North American English, is a tall stout Poaceae, grass that produces cereal grain. It was domesticated by indigenous peoples of Mexico, indigenous peoples in southern Mexico about 9,000 years ago ...

asparagus Asparagus (''Asparagus officinalis'') is a perennial flowering plant species in the genus ''Asparagus (genus), Asparagus'' native to Eurasia. Widely cultivated as a vegetable crop, its young shoots are used as a spring vegetable. Description ...

palm Palm most commonly refers to: * Palm of the hand, the central region of the front of the hand * Palm plants, of family Arecaceae ** List of Arecaceae genera **Palm oil * Several other plants known as "palm" Palm or Palms may also refer to: Music ...

cucumber The cucumber (''Cucumis sativus'') is a widely-cultivated creeping vine plant in the family Cucurbitaceae that bears cylindrical to spherical fruits, which are used as culinary vegetables.tomato The tomato (, ), ''Solanum lycopersicum'', is a plant whose fruit is an edible Berry (botany), berry that is eaten as a vegetable. The tomato is a member of the nightshade family that includes tobacco, potato, and chili peppers. It originate ...

squash Squash most often refers to: * Squash (sport), the high-speed racquet sport also known as squash racquets * Squash (plant), the fruit of vines of the genus ''Cucurbita'' Squash may also refer to: Sports * Squash (professional wrestling), an extr ...

cassava ''Manihot esculenta'', common name, commonly called cassava, manioc, or yuca (among numerous regional names), is a woody shrub of the spurge family, Euphorbiaceae, native to South America, from Brazil, Paraguay and parts of the Andes. Although ...

radish The radish (''Raphanus sativus'') is a flowering plant in the mustard family, Brassicaceae. Its large taproot is commonly used as a root vegetable, although the entire plant is edible and its leaves are sometimes used as a leaf vegetable. Origina ...

eggplant Eggplant (American English, US, Canadian English, CA, Australian English, AU, Philippine English, PH), aubergine (British English, UK, Hiberno English, IE, New Zealand English, NZ), brinjal (Indian English, IN, Singapore English, SG, Malays ...

guava Guava ( ), also known as the 'guava-pear', is a common tropical fruit cultivated in many tropical and subtropical regions. The common guava '' Psidium guajava'' (lemon guava, apple guava) is a small tree in the myrtle family (Myrtaceae), nativ ...

melon A melon is any of various plants of the family Cucurbitaceae with sweet, edible, and fleshy fruit. It can also specifically refer to ''Cucumis melo'', commonly known as the "true melon" or simply "melon". The term "melon" can apply to both the p ...

chickpea The chickpea or chick pea (''Cicer arietinum'') is an annual plant, annual legume of the family (biology), family Fabaceae, subfamily Faboideae, cultivated for its edible seeds. Its different types are variously known as gram," Bengal gram, ga ...

, and

ginger Ginger (''Zingiber officinale'') is a flowering plant whose rhizome, ginger root or ginger, is widely used as a spice and a folk medicine. It is an herbaceous perennial that grows annual pseudostems (false stems made of the rolled bases of l ...

.MacGowan, J. B
The Reniform Nematode.
Nematology Circular No. 32. Florida Department of Agriculture and Consumer Services. 1977. Certain plants are considered to be non-hosts of the nematode, such as

little barley ''Hordeum pusillum'', also known as little barley, is an Annual plant, annual grass native to most of the United States and southwestern Canada. It arrived via multiple long-distance Biological dispersal, dispersals of a southern South American s ...

, common barnyard grass, pangola grass,

peppers Pepper(s) may refer to: Food and spice * Piperaceae or the pepper family, a large family of flowering plants ** Black pepper ** Long pepper ** Kampot pepper * ''Capsicum'' or pepper, a genus of flowering plants in the nightshade family Solanaceae ...

, and some

cultivar A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...

s of

black mustard ''Rhamphospermum nigrum'' (syns. ''Brassica nigra'' and ''Sinapis nigra''), black mustard, is an annual plant native to cooler regions of North Africa, temperate regions of Europe, and parts of Asia. It is cultivated for its dark-brown-to-black se ...

oat The oat (''Avena sativa''), sometimes called the common oat, is a species of cereal grain grown for its seed, which is known by the same name (usually in the plural). Oats appear to have been domesticated as a secondary crop, as their seeds ...

spinach Spinach (''Spinacia oleracea'') is a leafy green flowering plant native to Central Asia, Central and Western Asia. It is of the order Caryophyllales, family Amaranthaceae, subfamily Chenopodioideae. Its leaves are a common vegetable consumed eit ...

, and

sugarcane Sugarcane or sugar cane is a species of 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 stout, jointed, fib ...

Morphology

The reniform nematode has esophageal glands overlapping the intestine and a short stylet. The dorsal esophageal gland orifice is located posterior to the stylet knobs.Shurtleff, M. C. and C. W. Averre. ''Diagnosing Plant Diseases Caused by Nematodes''. St. Paul, Minnesota: American Phytopathological Society Press. 2000. The immature female is slender and may be spiral- or C-shaped in death.Dropkin, V. ''Introduction to Plant Nematology''. John Wiley & Sons, Inc. 1980. 293p. It is about 0.3 to 0.5 millimeters long. The mature female has a swollen, kidney-shaped body with a short tail, a short, thin stylet with rounded stylet knobs, a three-part esophagus, a long and narrow isthmus, and a well-developed metacarpus. The vulva is just behind the middle of the body. The male is

vermiform Vermes (" vermin/vermes") is an obsolete taxon used by Carl Linnaeus and Jean-Baptiste Lamarck for non-arthropod invertebrate animals. Linnaeus In Linnaeus's ''Systema Naturae'', the Vermes had the rank of class, occupying the 6th (and last) ...

: with a wormlike appearance. It has a weak stylet, curved

spicule Spicules are any of various small needle-like anatomical structures occurring in organisms Spicule may also refer to: *Spicule (sponge), small skeletal elements of sea sponges *Spicule (nematode), reproductive structures found in male nematodes ( ...

s, and a pointed tail. The esophagus is reduced.

Life cycle

''R. reniformis'' is sedentary semi-endoparasite on the roots of plants. The female penetrates the root and remains in one position at a permanent feeding site with its posterior end projecting from the root. The immature female is the infective agent, attacking the root and growing to maturity at its feeding site.Luc, M., et al. (Eds.
''Plant Parasitic Nematodes in Subtropical and Tropical Agriculture''. 2nd Edition.
CABI Publishing. 2005. pp 38, 39, 709-20. Males and juveniles live in the soil; males are not parasites and do not feed. Under

drought A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, ...

conditions the nematode can persist up to two years outside a host by entering an

anhydrobiotic Cryptobiosis or anabiosis is a metabolic state in extremophilic organisms in response to adverse environmental conditions such as desiccation, freezing, and oxygen deficiency. In the cryptobiotic state, all measurable metabolic processes stop, ...

state. The life cycle is 17 to 29 days long. The juvenile molts once while still inside the egg.Lawrence, G. W. and K. S. Reniform Nematodes. In: Kirkpatrick, T. L. and C. S. Rothrock. (Eds.) ''Compendium of Cotton Diseases''. 2nd edition. St. Paul, Minnesota: The American Phytopathological Society Press. 2001. pp. 42–44. The eggs hatch in 8 to 10 days. The juvenile molts three times to reach the immature stage. The immature female parasitizes the root for one to two weeks. During this time the male deposits sperm, which the female stores until her gonads mature. The nematode can also reproduce via

parthenogenesis Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means the development of an embryo from an unfertiliz ...

, without fertilization. Upon maturity the female exits the root and lays up to 200 eggs in a gelatinous matrix.

Host-parasite relationship

Sweetpotato infected by reniform nematodes14618951783

When the immature female penetrates the root, a feeding tube forms from stylet secretions. Reniform nematode infestations can be hard to detect, as they do not cause galls or other obvious symptoms. Instead, it causes symptoms in the host plant that resembles those of moisture and nutrient deficiencies. Reniform nematode cause hypertrophy in the

pericycle The pericycle is a cylinder of parenchyma or sclerenchyma cells that lies just inside the endodermis and is the outer most part of the stele of plants. Although it is composed of non-vascular parenchyma cells, it is still considered part of the v ...

cells of seedling roots and in the

periderm Bark is the outermost layer of stems and roots of woody plants. Plants with bark include trees, woody vines, and shrubs. Bark refers to all the tissues outside the vascular cambium and is a nontechnical term. It overlays the wood and consists ...

cells of the roots of older plants.Oteifa, B. A. (1970). The reniform nematode problem of Egyptian cotton production. ''Journal of Parasitology'' 56, 255. Root growth slows and secondary root development is limited. Root

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. The term "necrosis" came about in the mid-19th century and is commonly attributed to German pathologist Rudolf Virchow, who i ...

has been observed in pineapple and banana. Shoot growth suppression and reduction of fruit quality has been observed in crops such as pineapple. In sweet potato, early infection of reniform nematodes results in tuber cracking leading to poor storage quality. Infested plants can become stunted and

chlorotic 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 ...

Wilt disease A wilt disease is any number of diseases that affect the vascular system of plants. Attacks by fungi, bacteria, and nematodes can cause rapid killing of plants, large tree branches or even entire trees. Wilt diseases in woody plants tend to fal ...

can follow when opportunistic

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

such as ''

Fusarium ''Fusarium'' (; ) is a large genus of filamentous fungi, part of a group often referred to as hyphomycetes, widely distributed in soil and associated with plants. Most species are harmless saprobes, and are relatively abundant members of the s ...

'' and ''

Verticillium ''Verticillium'' is a genus of fungi in the division Ascomycota, and are an anamorphic form of the family Plectosphaerellaceae. The genus used to include diverse groups comprising saprobes and parasites of higher plants, insects, nematodes, mol ...

'' infect the plants, a process observed in cotton. Secondary fungal infection can also cause root decay. Damage from ''R. reniformis'' is directly related to the number of nematodes present when the crop is planted. Variation among nematode populations, hosts, environmental conditions, and soil types may alter the threshold or economic injury level across the geographic distribution of the nematode.

Management

Management can be challenging, as reniform nematodes have been found in depths greater than 1m in soil and appear to become dominant over other nematodes such as southern root knot nematode (''M. incognita).'' Some plants are resistant to this nematode. In susceptible taxa, chemical control is one of the most common management practices.

Nematicide A nematicide is a type of chemical pesticide used to kill plant- parasitic nematodes. Nematicides have tended to be broad-spectrum toxicants possessing high volatility or other properties promoting migration through the soil. Aldicarb (Temik), a ...

s before and after planting can be effective.

Intercropping Intercropping is a multiple cropping practice that involves the cultivation of two or more crops simultaneously on the same field, a form of polyculture. The most common goal of intercropping is to produce a greater yield on a given piece of land ...

and

crop rotation Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. This practice reduces the reliance of crops on one set of nutrients, pest and weed pressure, along with the pro ...

, especially with resistant or non-host plants, is used as

cultural control In agriculture cultural control is the practice of modifying the growing environment to reduce the prevalence of unwanted pests. Examples include changing soil pH or fertility levels, irrigation Irrigation (also referred to as watering of pla ...

to improve soil, increase antagonistic microorganisms, and reduce nematode populations.

French marigold ''Tagetes patula'', the French marigold, is a species of flowering plant in the family Asteraceae, native to Mexico and Guatemala with several naturalised populations in many other countries. It is widely cultivated as an easily grown bedding p ...

(''Tagetes patula'') and sunn hemp (''Crotalaria juncea'') are recommended for these uses.

Fallowing Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. This practice reduces the reliance of crops on one set of nutrients, pest and weed pressure, along with the pro ...

the land is another cultural practice that can be utilized, but it is much less effective than rotating resistant species, as nematodes can persist in the soil for a long time and feed off of weeds. The fungus'' Purpureocillium lilacinum'' and bacteria '' Bacillus firmus'' have shown potential to become commercial agents of

biological pest control Biological control or biocontrol is a method of controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or plants by using other organisms. It relies on predation, parasitism, herbivory, or ot ...

against the nematode in cotton.

References

{{Taxonbar, from=Q7370726 Tylenchida Plant pathogenic nematodes Nematodes described in 1940