The whip smut caused by Sporisorium scitamineum (Phylum: Basidiomycota, Order: Ustilaginales) is considered as the most serious and widely spread disease of sugarcane, known to affect both qualitative and quantitative components causing the substantial economic losses [9,10,11,12,13,14,15]. The severity of the disease often depends on the pathogen races, environmental conditions and cultivars grown [16,17]. It becomes more serious under favorable conditions, which can even cause a complete crop failure in extreme cases [18]. Besides the direct yield loss, the whip smut can cause the significant reduction in sucrose content, purity and other juice quality indicators [19,20,21]. Different races of S. scitamineum are known to exist. Random amplification of polymorphic DNA (RAPD), sequence-related amplified polymorphism (SRAP) [22], amplified fragment length polymorphism (AFLP) [23] and internal transcribed spacer (ITS) sequence analysis [24,25] have been applied to evaluate the intraspecific diversity among the S. scitamineum populations.
It is known that the practice of ratooning has also influenced smut intensity and resulted in yield losses. Ratooning of susceptible cultivars significantly increased smut incidences, causing tremendous yield losses of about 67% in the third ratooning [87]. Ratooning of a chewing type cultivar, highly susceptible to whip smut, should be avoided, otherwise it may result in a huge number of diseased stools and the complete yield loss [88]. In terms of yield, the chewing type sugarcane cultivar was suffering more with high inoculum load of S. scitaminem as compared to the industrial type sugar cultivar [15].
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Host responses under control conditions were also observed for race differentiation. A greenhouse study involving seven sugarcane cultivars and pathogen isolates collected from Argentina, Florida, Hawaii, Taiwan and Zimbabwe indicated the presence of six distinguished races [118]. Similarly, a series of consecutive glasshouse and field pathogenicity trials involving S. scitamineum isolates of two main sugarcane regions of Australia on the same sets of cultivars clearly indicated the variation between the isolates of these two regions [119].
Resistance screening is a very old practice to combat whip smut disease. In India, among 11 cultivars, artificially infested before planting, four appeared susceptible, three moderately susceptible and three moderately resistant [143]. In another study carried out in India, only 7 out of 20 cultivars were resistant against whip smut [104]. A report indicates the field evaluation of 84 cultivars in Brazil artificially inoculated with the smut pathogen [144]. Until 1974, the whip smut disease spread widely in Hawaii, USA. About 70% of commercial varieties showed various levels of susceptibility to whip smut [145]. Therefore, large-scale varietal evaluation programs were initiated to find out resistant germplasm against this devastating disease [145,146]. In a comprehensive sugarcane breeding program of Australia, 1705 and 481 accessions were planted in neighboring Indonesia and the ORIA region of Western Australia in 1998, which revealed that most screened cultivars (69%) are susceptible to smut. Afterwards, 1007 and 1600 cultivars were screened in Queensland during 2006 and 2007, respectively [147].
A field trial conducted at Guangxi province, China revealed that among seven commercial cane varieties, which were artificially inoculated with smut pathogen, three appeared as moderately resistant, two moderately susceptible and two were susceptible to whip smut infection [117]. In another study, among 30 cultivars, which were inoculated with pathogen prior to sowing screened under field conditions, nine were highly resistant, three resistant, three moderately resistant, three moderately susceptible, nine susceptible and three highly susceptible [116]. Out of 34 sugarcane cultivars planted under field conditions in Guangdong province (China) after inoculation with S. scitamineum, five showed highly resistant reaction, four resistant, two moderately resistant, eight moderately susceptible, seven susceptible and nine were highly susceptible to whip smut [138]. In Bangladesh, 43 cultivars screened under field conditions after artificial inoculation with smut pathogen showed that five were highly susceptible, 16 susceptible, seven moderately susceptible, three moderately resistant and 12 resistant to whip smut disease [148]. Among 32 cultivars obtained from the French Agricultural Research Centre for International Development (CIRAD) and screened under Ethiopian conditions, three were very highly susceptible, two susceptible, one intermediate, nine moderately resistant, seven resistant, three highly resistant and seven very highly resistant [149]. Wild relatives and hybrids of cultivated canes also appeared good source of resistance against whip smut. A study conducted in Sri Lanka revealed that out of 455 entries artificially infested with S. scitamineum, 124 were free from infection, including 86 hybrids, 16 cultivars of Erianthus arundinaceus and 16 of Saccharum spontaneum [150]
Endophytic bacteria, especially certain Bacillus spp., also showed promising results against sugarcane smut. However, comprehensive screening is the prerequisite to find out effective strains, as out of 119 strains, only eight showed antagonistic potential under in vitro conditions, while four remarkably reduced smut development in greenhouse conditions and only two i.e., Bacillus pumilus and B. axarquiensis, performed well under field conditions. These two species not only brought significant reduction in whip smut development, but also enhanced quantitative and qualitative parameters [178]. Similarly, compounds isolated from specific strain of B. siamensis showed antagonistic characteristics against whip smut pathogen [179]. One specific strain of bacterial pathogen Burkholderia gladioli, which was isolated from sugarcane leaves, also showed biocontrol potential against whip smut in laboratory and field experiments [180].
In cane based sugar industry the sugar concentration in the extracted juice after lime (CaO + H2O) treatment and color removal (clarification step) usually reaches around 5% (mass basis). This stream subsequently enters into series of evaporators to get concentrated. Presence of excess calcium in the postfloculation and precipitation stage of clarified sugar juice creates series of nuisance [1] to the subsequent stages (evaporators, etc.) in sugar industries affecting product quality as follows.(1)Scale formation in the evaporators.(2)Improper crystallization.(3)Molasses percentage may increase due to inversion of sugar in alkaline medium.(4)Storage is hampered because of hygroscopic nature of these metals ions.(5)Excess calcium is not hygienic as well.
hydrolysis efficiency of common reed and sugar cane bagasse to produce fermentable sugar [117, 118]. In case of enzymatic hydrolysis of polysaccharides, it significantly increases the glucose yield. [119]. Olefinic compounds, like sodium cinnamate (Na-CIN), exhibit the photoswitchable recovery of solute under exposure to UV irradiation. Various organic solutes, such as cinnamic acid, aspartic acid, curcumin, thymol, benzocaine and natural compounds, like forskolin and curcumin, are easily recovered under uV irradiation with the help of Na-CIN [120]. Hydrotropic solubilization helps to facilitate the aqueous solubility of rapamycin, a poorly water-soluble immunosuppressive drug, up to a 1000 times [121]. In extractive isolation process, hydrotropes reduce the use of harmful organic
[118]H. Mou, E. Heikkila, P. Fardim, Topochemistry of environmentally friendly pre-treatments to enhance enzymatic hydrolysis of sugar cane bagasse to fermentable sugar, J. Agric. Food. Chem. 62 (2014) 3619-3625.
[118]Mou H., Heikkila E., Fardim P. To-pochemistry of environmentally friendly pre-treat-ments to enhance enzymatic hydrolysis of sugar cane bagasse to fermentable sugar // J. Agric. Food. Chem. 2014. Vol. 62. Pp. 3619-3625. 2ff7e9595c
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