This paper examines the valuable contributions of oil palm and its natural history in the palm oil industry. The basal stem rot disease is a primary cause of infection which hampers the growth and profitability of the palm especially in South East Asia where reports of the disease are rampant. The root cause (pun intended) of the basal stem rot is the G. boninense pathogen which attacks the root of the oil palm. Several ways to control the succumbing to this disease are available although no permanent cures have been met.
Lignin enhances the process of lignification which forms a veritable enforcement against pathogenic attack hence lignin is one of the solution to this enigma. 1. 1 Oil Palm The oil palm is native to countries in the Americas and Africa; however, early settlers have introduced the tropical growing plant to Malaysia, Indonesia. The oil palm belongs to the Arecaceae palm family. The oil palm is the raw material for the commercialized palm oil. A soft oleaginous pulp encircles the fleshy, pericarp kernel of the oil palm. The leaves of the oil palm assume a pinnate form with multiple leaves stemming from the main branch.
The lignin found in the oil palm is a ligneous component embedded within the oil palm cell wall where one discovers the cellulose. The lignin is essential to reinforce the xylem vessels, which classifies the oil palm as a vascular plant where the tissues lignify or convert into a woody nature. Palm oil, the product of the oil palm, is made from the kernel and the fleshy endocarp tissue. Palm oil has a roseate appearance because of significant quantities of beta-carotene. It carries monosaturated and polysaturated fats such as laurate, palmitate, oleate, myristate, linoleate, and stearate.
Palm oil is healthy since it has no cholesterol. As a chief cooking ingredient palm oil is in high demand, used chiefly in countries such as Asia, Africa, and now America with the new wave of health consciousness. Unfortunately, the Amazonian forests, African forests, and Asian rainforests face exploitation and animal extinction with large areas of land being cleared and substituting vast plains of oil palm estates. Biodiversity and ecosystems are disregarded for commercial profit. 1. 1. 1. Oil Palm Physiology The structure of the oil palm fruit is subdivided into four sections: the exocarp, the endocarp, mesocarp, and the kernel.
The exocarp is the outer skin; the mesocarp is the corpulent pulp; the kernel which resembles the coconut’s white interior; and the fibrous endocarp encloses the kernel. Glycerides are the main ingredient of palm oil which proceeds from glycerols and palmitic fatty acids which can either be soluble or non-soluble. The exocarp has a reddish-brown pigment which it obtains when mature and ripe. The tocopherols and tocotrienols are antioxidant in function, holding carotene which enhances the color and flavor of the oil. The palm oil’s carotene is the mineral which lends this red-brown color.
The oil palm is very rich in oleic acid, containing up to 40% oleic acid. The palm oil inflorescences are considered hermaphroditic or monoecious which serve for self-reproduction. The male inflorescence’s form contains elongated, vertical protrusions whereas the female inflorescence has a shorter stalk mantled by spiky bracts and stigmatic receptacles. The male and female flowers appear successively so that at any given moment, male and female flowers may bloom together. Once pollinated, the female flowers drop and are substituted by scores of fruit developing among the spikes.
The oil palm leaves are known to have the most accelerated rates of photosynthesis. A reason attributable to this phenomenon is its evergreen-ness since it uses the photosynthetic C3 II pathway which facilitates trees with moderate solar exposure, carbon dioxide concentration of 200 ppm, moderate subterranean water reserves, and moderate rainfall. As “an unbranched evergreen tree, (the oil palm reaches) a height of 18-30m … sprouting adventitious roots” (El Bassam 1998). The deep roots can plunge more than a meter to five meters below anchoring firmly anchoring the tree and tapping into subterranean water reserves.
In the early stages of growth, the oil palm’s roots are lignified (El Bassam 1998). 1. 1. 2. Land Selection Good cultivation of oil palms requires flat soil for easy transportation on and off the plantation, agricultural machinery, and lessens the effects of soil erosion. Depth of soil is necessary for optimum root penetration, and for the suction and absorption of plant water and plant minerals. Permeable soil helps the soil to be more aerated earth for free movement of earthworms, and air circulation for carbon dioxide fixation. Fertile soil also speeds up photosynthesis and ensures steady growth and fruitful production.
The selection of land is based on several influences the oil palm’s nutrition requirements, climate conditions, biomass, groundcover conditions (erosion), soil porosity, organic matter, soil fertility, soil depth, and intended agricultural practice. Factors such as “the effect of vegetation type, plantation age, and spatial position (distance to closest trunk) on the palm oil’s soil was demonstrated by the high correlation between fine root (tertiary and quaternary roots) biomass of the system and soil content” (Syahrinudin 2005).
Other elements, weighing heavily on the soil composition and by extension, soil productivity are alterations in soil temperature, soil structure, and moisture. When choosing optimal land, agriculturists and farmers steer clear from sloping lands, rather, flat, undulating lands suit best oil palm farming. To minimize soil leaching, a terraced structure of oil palm is usually advised so that run-off of valuable nutrients boost growth in other places. Water holding capacity and drainage systems also impact soil cultivation of the oil palm since substantial quantities of water and good water balance are needed for growth and maintenance.
Many farmers and oil palm companies prefer to locate extensive oil palm plantation estates in the Equatorial belt (Amazon forests) where biomass is high, water is consistent, temperatures are adequate, and the soil exposure is mantled by mulching and front trees. However, despite these precautions, soil fertility has steadily declined and soil erosion has increased in oil palm terrains. Erosion under the mature oil palm has ranged from 6. 6 – 20. 5 mg/ha/year (Hartemink 2003). Oil palms demand exponential levels of biomass to continue existence.
Sandy soils, alluvial soils, and weathered ferrallitic soils in the cleared forests-turned plantations have unstable structures, may have low base saturation levels or strong acidity, however, oil palm can thrive in acidic levels from pH 4. 0-5. 0 (Young 2008). Prolonged cultivation on plateau or savannah soils also produces surface denudation, gradual to intense weathering. Sustainable organic matter which enhances fertility are leaf coverings (mulching), reduced soil exposure, and leguminous soil cover (Young 1980).
1. 1. 3. Nutritious Requirement The nutritional requirements necessary to oil palm cultivation, productivity, and sustainability vary since aimed yields, palm phases, planting technology, spatial sowing of crops, soil classification, groundcover conditions, and climate must be factored into the equation. Two critical components to promoting oil palm health include nitrogen (nitrates) and potassium. Other peripheral nutrients and micronutrients are zinc, phosphorous, boron, magnesium, and copper.
(Janick 2008) affirms that “large quantities of nutrients particularly nitrogen (N) and potassium (K) are immobilized in the vegetative tissue…the annual uptake of nitrogen is 193 kg/ha/year and potassium 251 kg/ha/year”. Recognizing the nutritive criteria for oil palm growth, farmers, companies, and agriculturists have embedded pueraria, a nitrogen fixing legume that smothers weeds, helps preserve soil moisture, and checks erosion” (Srivastava, Jitendra. Nigel J. H. Smith, Douglas Forno. Integrating Biodiversity in Agricultural Intensification: Toward Sound Practices).
The competition for nutrients between oil plants and weeds is keen therefore killing off the rival enables the oil palm to flourish. Sandy soils and peat soil need more fertilization since soil is already impoverished by nitrogenous mineralization. Sandy soils require higher quantities of boron while peat demands copper and zinc. Magnesium and potassium augment oil yield, aid in root growth and repair, photosynthesis (light conversion to energy), nitrogen efficiency, water uptake, and nutrient flow (Rankine 1999). 1. 1. 4. Production and Economic Importance
The oil palm is a billion dollar agricultural industry known by its high profitability more than any other vegetable oil including canola oil, soybean oil, sunflower oil, linseed oil, and corn oil (Carrere 2001). Palm oil is advantageous because it can withstand high temperatures for cooking and frying, and its composition remains relatively stable in storage, transportation, and handling (Bowden 2007). The palm oil market is cost efficient so that every 100 kilogram of oil palm kernel yields 22 kilograms of extracted palm oil.
The production of palm oil recompenses the effort in which each hectare gives an annual return as much as four to ten tons of oil per hectare, on average (Block 2009). The diverse uses of palm oil which span from cooking, fuel, animal food, to mulching add to its profitability. (USDA 2007) discloses that the “relatively low priced oil is used for a variety of purposes. The world demand for palm oil has soared in the last two decades, first for its use in food, consumer products and more recently as the raw material forf biofuel…
In the US, a recent wave of dietary focus on the trans-fat issues has led to increased consumption. ” Malaysia exports 43% of the world’s palm oil and Indonesia 44%, standing as the leading producers of palm oil. (Basiron 2002) states that oil palm has become a major cash crop for Malaysia, Indonesia, Thailand, Nigeria, Colombia, Ecuador, Cote d’Ivoire, Honduras, Papua New Guinea, Brazil, and Costa Rica (in order of prominence). 1. 1. 5. Diseases on Oil Palm
Major diseases that attack the oil palm are rot diseases, namely the spear rot, basal stem rot, dry basal rot, trunk, stem rot and bud rot. About thirty two disease and disorders infect the oil palm worldwide, which adversely infect the oil palm and hampers overall health and productivity. (Aderungboye 1977 & Duke 1983) records that out of the thirty-two about 8 make a huge impact causing grievous economic losses such as freckle (Cercospora elaeidis), blast (Pythium splendens and Rhizoctonia lamellifera), vascular wilt (Fusarium oxysporum f. sp.
Elaeidis), Armillaria trunk rot (Armillariella mellea); Corticium leaf rot (Corticium solani), Marasmius bunch rot (Marasmius palmivora); sudden wilt (Curvularia eragrostidis), bunch rot (Marasmius palmivora), basal rot (Ceratocystis paradoxa), anthracnose (Botryodiplodia palmarum, Melanconium elaeidis, Glomerella cingulate) and lastly Ganoderma trunk rot (Ganoderma spp. ) . In addition to naturally-occurring diseases and pests also provoke disorders. (Duke 2001) publishes that “the major pests of oil palm in various parts of the world are the palm weevils (Rhynchophorus phoenicis, R palmarum, R.
ferrugineus), rhinoceros beetles (Orchytes rhinoceros), leaf miners (Coelaenomenodera elaeidis, hispolepsis) and slug caterpillar (Parasa viridissima) and bagworms (Cremastophysche pendula, Metisa plana, Mehasena corbetti). Often the prevalence of disease is determined according to geographic location since climate and temperatures figure in the development and propagation of oil palm disease and pests. Vegetative putrefaction, withering, and jaundiced appearance contaminate the oil palm. The aforementioned symptoms characterize spear rots (poisoned by the Erwinia sp.
bacterium where the whorl regions in the plant are affected. Bud rot is a generic name applied to plant decay which is brought by a pathogen. However there has been ambiguous nomenclature-since certain oil palm diseases manifest similar traits for example bud rot, lethal yellowing and sudden wither (Chinchilla 2007). Fungi are documented as the origin of bud rot disease which obstructs growth of young leaves primarily in South American palm oil plantations, limiting oil membranes in the endocarp thus lowering output. Foliar tissue decompose as the fungi accelerates disintegration 2.
2 Ganoderma boninense Ganoderma, the genus, has roughly 214 species which pose many problems with morphological identification because of a severe shortage of research and evidence. Popular strains of the fungi include G. steyaertanum sp. , G. lucidum, G. steyaertanum, G. cupreum, G. incrassatum, G. austral, G. weberianum, G. tornatum, G. cupreum, G. microsporum , G. weberianum, G. colossum and last but not least, G. boninense, which was found by Japanese scientists on the Japenese island of Bonin. The G. boninense disease was discovered in 1931 as a disease which assaulted older oil palms.
However, after the replanting, the disease began to manifest in younger oil palms. Ganoderma butt rot or Basal stem rot disease is lethally noxious to the oil palm. Basal stem rot is the most widespread disease affecting oil palms worldwide. Two pathogenic strains of the disease are caused by Ganoderm zonatum (native to the U. S) and the Ganoderm boninense (native to South East Asia). The characteristics distinguishing basal stem rot are yellowed leaves, stunted growth, blighted fronds withered by necrosis, and trunk tissue ridden with fungi.
The inherent potential of this disease to pollute an entire plantation makes it an epidemic and highly contagious (Elliot 2004). According to (Paterson 2007) the Ganoderma boninense appears as a white rot fungus which breaks down lignin to carbon dioxide and water. This action decomposes the essential cell wall of the plant through the cellulose. Through biodegration, the lignin loses its key nutrient in the oil palm. Transmission of the disease is operated via bacteria’s spores.
Ganoderma disease passes through three principal stages called melanised mycelium, basidiospores and pseudosclerotia (Susanto 2005); so that the popularly identified basal stem rot is only one phase in the in pathogenic cycle. The manifestation of the infection however presents itself as a rotting in the upper stems of the oil palm (Sanderson 2005). Ganoderma boninense contains a heterothallic contagion with a tetrapolar mating system and multiple alleles at both mating type loci. This structure places the G. boninense at an advantages for interpopulation breeding and maximum transmittance (Pilotti 2005).
This predisposition within the alleles foments colonization within the oil palms (Pilotti 2005) and seriously hampers palm oil productivity in South East Asia. 2. 2. 1 Nomenclature and systematic (Flood 2000) reports the genus Ganoderma …was introduced by Finnish mycologist Peter Adolf Karsten in 1881 where he first named the species he encountered Polyporus lucidus. The etymology of ganoderma derives from the Greek ganos, signifying brightness, shining, and derma which of course means skin. The ganoderma actually has a sheeny surface.
The subsequent pioneer to discover more on Ganoderma was French mycologist Narcisse Theophile Patouillard who explained a species of Ganoderma, exchanging some of the polyporus names (Flood 2000). Marinus Anton Donk in 1933 suggested that a subfamily to the Polyporaceae family called the Ganodermatoideae, soon this subfamily was later promoted to the Ganodermataceae (Cannon 2007). Since 2005, over 386 species of Ganodermataceae exists. The G. boninense strain of disease spreads from Australasia, Sri Lanka, Malaysia, the Philippines, extending to the Japanese islands of Kyushyu and Bonin (Steyaert 1975).
Ganoderma belongs to the polypore genus which has a mushroom semblance and abound in tropical regions since hot temperatures favors growth and proliferation. The Genoderma belongs to the fungi kingdom, basidiomycota (phylum), agaricomycetes (class), polyporales (order)and the Ganodermataceae (family). 2. 2. 2 Economic importance The G. boninense cuts short the longevity of the oil palm and infects other hence, it has a blighting effect on the economy of countries such as Malaysia, Indonesia, and Papua New Guinea who lean on oil palm cultivation for its source of income.
In 1996, for every 1% of oil palm trees infected by the Ganoderma virus, palm oil farmers and producers lose close to $38 million dollars. In plantations experiencing epidemic infections, occurrence rates can be as high as 50-80%. The G. boninense ravages the oil palm such that palm yields less and less fruit until it dies. The average life span of an oil palm is 20-25 years; however, in an infected oil palm tree the time of life is only 10-15 years. Many laborers in Malaysia and Indonesia depend on the oil palm industry as a means of income. So not only do the government, farmers, companies, and corporations suffer but the average man.
Beside the decimated palm oil population, palm oil yield reductions range from 35-46% (Bernama 2010) which significantly lowers profit. The only known way to combat G. boninense is replanting therefore more raw materials and extensive energy has to be re-invested into palm oil cultivation and maintenance. The repetitiveness of the disease injures the yield per hectare ratio. Oil palm producers report that “replanting is costly and leads to loss of income for at least five years” 2. 2. 3 Disease cycle, infection and symptom The three stage disease cycle composes of melanised mycelium, basidiospores and pseudosclerotia.
The first stage involves mycelium contact whereby the root is fixed to tissues withing the endodermis. It has been discovered that the mycelia contact causes the fungi to be so widespread. The branch-like hyphae converts to a thick-membraned structure. Secondly the basidiospores which are the agent-transmitters covertly corrupt the basal stems while showing no outward signs of decay. The pseudosclerotial phase expresses the stage where the basal tissues are de-lignified so that the fungal breakdown of the cellulose results in the rottenness found in the basal stem.
The Ganoderma develops the pseudosclerotial plates to provide and maintain an environment conducive to necrosis (Agosin 1989). The yellowing of the leaves and spear rotting are among the first signs symptomatic of the disease. In the embryonic stages the leaves are folded like an arrow and do not unfold, hence severely limiting the oil palms’ ability to photosynthesize. The G. boninense rots the base of the oil palm trunk where the basidiomycete is a saprophyte which affects. The fungi deteriorate the internal xylem vessels crucial to the oil palms’ circulatory system which impedes water accessibility and plant nourishment.
Later on as the disease advances, the foliage gets jaundiced and growth halts. “Older fronds yellow…in some regions younger and younger leaves become paler and chlorotic” and already developed leaves become diminish. After the initial infection, the incubation period for an oil palm plant can last between 2-4 years until its untimely death. 2. 2. 4 Epidemiology (Craig 1999) points out Ganoderma basidiospores are a part of airspora, living and travelling in the atmosphere. The optimal climate for transmission is the warm, tropical weather and activity increases between June-October.
The basidiospores are linked to the basidiomycetes, another group connected to the Fungi kingdom with over 25,000 variations. In the G. boninense phases, there is a dangerous latent stage of development where symptoms may even not appear (although already infected), for further decay to advance, scientists have discovered that there is a mechanism which triggers the regeneration and proliferation of the disease in the roots. Daily meterological vicissitudes in temperature and precipitation affect spore concentrations and the tendency of some oil palm plants to die quicker than others.
Each oil palm plant is equipped with a benign colony of arbuscular mycorrhizal fungi which actually ameliorates root development, vascular circulation, and stimulates vegetative growth. In order to combat the noxious effects of G. boninense, agri-scientists have turned to grafting the arbuscular mycorrhizal fungi in the contaminated roots, since the root area is where the bacteria targets. (Rees 2005) proves that an analysis on the structure of the shows that the G. boninense pathogen alters not only the root cortex, but also invades, going inside the cell.
Like a parasitic endophyte, it colonizes the basal cells, causing the hyphae to aggregate. This deadly process contributes to the formation of basidiocarps and the opening of the basidiospores, aerially releasing the spores for diffusion. At the same time, isolates have been gleaned where colonization does not occur and a solitary instance of infection may crop up. Pathogenic inoculation is a popular method of temporarily treating this mysterious disease. Because of its clandestine, underground attack on the roots, it is difficult to manage once the oil palm is contaminated and the best measure is to take preventative ones.
2. 3 Disease control and management strategies The physical, chemical, and biological means of control over the G. boninense cover the three branches of science where each subdivision meaningfully and practically adds to the commercial and agricultural welfare of the oil palm. Although as yet there exists no remedy to exterminate the G. boninense pathogen, proactive strategies can be applied to stem the advancement and minimize vegetative and raceme damage in the oil palm. Physical, chemical, and biological control are the weapons which can be harnessed for the management of G. boninense.
The physical mode of control displays the ways where the farmer can get rid of certain corrupting influences in the plant using simple, physical removal. The ways of physical control are mounding, deboling, sanitization of palms, fallowing, and windrowing. The chemical form of protection comes in using mainly fungicides and solutions to kill off the pathogenic fungus. Chemical concoctions are temporary but still do the job of partially exterminating the disease. Biological control is the best means of disease management since there are little repercussions on the oil palm crop and has a more lasting effect.
2. 3. 1 Physical control Five main steps for physical control of the effects of the G. boninense bacteria are deboling, mounding, widened spacing, fallowing, expeditious removal, and windrowing. Deboling describes the process where the oil palm is ridded of the old palm stump, where loci of the infestation occur. Periodic clearing lengthens the lifespan of the palm. The trunk/ bole is one of the prime areas of attack so once observe, excising the infected bole of the palm is a temporary remedy.
Mounding or hilling the oil palm raises the soil levels exposing more roots to the sunlight (maximizing photosynthesis and stimulate root development); rotting is also substantially decreased since conditions of decay rely on waterlogged and stagnant soil to thrive; air pockets in the soil brings down the moisture, and nutrients get to circulate and get more even distribution in the soil. Widening the distance between one oil palm from another also helps lower the tendencies of G. boninense infection since close association is needed for propagation and perpetuation.
Leaving the land to fallow also helps put a physical control on proliferation since fallowing gradually enriches the soil and enables the planter to start all over. Physically and quickly removing the plague-ridden and dead palms is also another crucial step in stemming the tide of infection owing to the high level of contagion. Windrowing breaks up the soil and limits the growth of the fungi beneath the soil’s surface. Windrowing kills selectively kills pathogenic bacteria by heat, ammonia, and microorganisms. 2. 3. 2 Chemical control In the face of the pathogenic threat of G.
boninense, no standard cure has been found. However precautionary and ameliorative measure to retard the progress of this disease has been sought after. in vitro investigations on the microbe activity, and fungi-toxicity linked syringic acid, 4-hydroxybenzoic acid and syringic acid to the inhibition of G. boninense. Pathogenicity experiments have uncovered a 60-70% rate of morbidity when located along coastal regions. Chemical control of the G. boninense oil palm encompasses fungicidal spraying, soil inoculation, soil drenching, and trunk inoculation.
Trunk injection describes the fungicidal inoculation of uninfected tissues in order to control the spread of the fungi, thus prolonging the life span of the oil palm. The hydrostatic mini-tractor comes with nozzle-like tube using a pump where at high pressures, the fungicide is inserted into the oil palm’s tissue (Jelani 2004). The chemical inoculation was found to be very effective and efficient because it allowed focus on a particular area and the time taken to vaccinate one oil palm is very short, 1-3 minutes.
Another chemical method of control is the inoculation of oil palm seedlings. Seeds which have already germinated are cast into a solution of endophyte treatments and inoculum suspensions. After the seedlings were infected with G. boninense, the plants showed a lesser incidence of disease compared with the un-inoculated seedlings. Chemicals such as drazoxolone, phytoalexin, cycloheximide, penconazole, benlate, tridemorph, tridemenol, hexaconazole et al are a few which manages the disease and checks the growth and spread of G. boninense.
Moreover, other fungicides such as triadimefon, carbonix, carbendazim, methfuroxam have been attempted to chemically alter the properties of the pathogen, however the results have not lead to a definite answer. In order to maintain protected from attack, fungicides must be used repeatedly and so is a short term solution to a perennial problem. The instances of chemical residue in the oil palm and the building of chemical tolerance against the fungicides are other components to the puzzle. As a consequence, the attention has shifted from chemical control to explore other alternatives.
2. 3. 3 Biological control Biological control options manipulate and implement other benevolent fungi, bacteria, and organisms to naturally reverse the lethal work of the G. boninense. Biological control is more advantageous to the chemical control agents since the effects are more lasting and environmentally friendly. Trichoderma harzianum, T. viride, Gliocladium viride, Pseudomonas fluorescens, and Bacillus sp. are a few options open. The experiments have revealed that T. harzianum, Gliocladium sp. and G. viride are more effective when compared to Bacillus sp.
where the incidence of disease significantly decreased. Endophytes offer a viable barrier against infection and succumbing, since as they work to silently propagate malignant cells, they can also be incorporated to spread and develop healthy cells at an exponential rate, while being shielded from untoward conditions in the soil. The genus Gliocladium sp. is a family related to Penicillium. It is an innocuous allergen and like a typical endocyte, gliocladium disseminate, develop, and colonize at vertiginous rates.
Like the Trichoderma, it grows verticillate Burkholderia cepacia (B3) and Pseudomonas aeruginosa (P3) isolates have given evidence of deterring the increase of G. boninense; hence keeping levels of the pathogen at a manageable state. P. aeruginosa (P3). And B. cepacia (B3) diminished fungal infection incidences by approximately 42% and the combination of P. aeruginosa and B. cepacia has effected a 54% decrease in infection. T. harzianum is very compatible with the pathogen of G. boninense and interacts readily with the fungi. The T.
harzianum, which is also a bacterial parasite, cleaves to the host (pathogen) and asphyxiates the infected hyphae, thus inhibiting the G. boninense by about 70%. 2. 4 Lignin and lignifications In lignification, lignin deposits accumulate within the plant cell walls, inclining them to a more ligneous nature. Lignification happens when the phenolic monomer units polymerize, producing radicals and conjugating them with other monomer radicals. Lignification is founded upon reproduction: the copulation of phenols with other ligneous strains. The stages of lignification surround three distinctive phases.
Firstly, the accumulation of lignin compounds around the middle lamella, otherwise called (CML) and the cell corners with also deposits of PEC and arabinose-galactose rich in HCs. The secondary stage describes the setting down of cellulose microfibrils (CMF) and hydrocarbons in the secondary wall. Finally at the tertiary level, lignification takes place after the deposition of the majority of the polysaccharides. Lignins are born from the coupling of the monolignols-courmaryl, sinaply alcohol, and coniferyl. These actions and reactions form complex entities of polymers and cross-breeds.
The lignin in the cell wall is a complex substance located in plants and even fungus. Lignin is unique since it lacks definition structurally, thus classified a biopolymer. It is essential in supporting and reinforcing wood material in the xylem vessels especially. Lignin not only supports the plant cell but also confers it with a solid structure, giving it an elongated shape. Lignin is an excellent conductor of water therefore supports the circulatory system via the xylem vessels; the vessels allow water and nutrients flow all around the plant.
Lignin has hydrophobic tendencies in which the water molecules repel from one another. Lignin is also located in the traceids and sclereids On the other hand, lignification conveys the process of the encrustation of lignin deposits on cell walls thus making the cell harder and more woody. Lignification restrains the growth of fungus and inhibits proliferation. The main enzyme components which hinder lignification are N(O-aminophenyl) sulfinamoyl-tertiobutyl acetate and N(O-hydroxyphenyl) sulfinamoyl-tertiobutyl acetate. As a result, lignified cells which were infected by lethal pathogens provoked more rapid fungal progression.
Lignin also decides the resistance of a plant structure and its susceptibility to disease. Lignin also makes accessibility to cellular food much harder because of its structure and substance. The more lignin, the less energy released in the food. The liability of lignin-carrying plants to be more attacked by fungi and bacteria grows, hence increasing vulnerability. Lignin also puts a limit on the transformation of lignocellulosic biomass into biofuel. 2. 4. 1 Introduction Lignin is very beneficial in mitigating the effects of the basal stem rot disease caused by the G.
boninense. The properties of lignin serve to protect the plant cell from foreign invasion by strengthening the walls. The process of lignification also utilizes enzymes such as peroxide and laccase to catalyze hormonal actions and reactions to carry out lignification. Since lignin comprises of sequences of polysaccharides, it is only natural for enzymatic activity to carry on the process. Copper and calcium are invaluable to lignin and by extension lignification since the intra- and extra-cellular activity are conferred a boost with these raw materials.
These plant nutrients help lignification to occur thus immunizing the plant cell from pathogenic attack. The more lignin a cell has, the higher the possibility of fortification. To a great extent, lignin depends on chemical bonding and merging to carry out lignification. As a result of the bonding, plant cells experience, better chances at fighting off potential attack and improving the cells’ structure through biosynthesis. In sum, the role of lignin in disease control, biosynthesis, peroxidase, laccases, role of copper and calcium in lignification.
2. 4. 2 Role of lignin in disease control Lignin and disease vulnerability go hand in hand. The lignin walls of the plant provide a strong barrier against invading pathogens, bacterium, fungus, and virus. Monolignol biosynthesis participates in cell wall apposition which is a defense mechanism which guards against fungal penetration by mildew cilia. Because of its strong material, the cells walls are almost impregnable. The cell wall apposition defense are gathered together to collectively withstand against infiltration.