Post-harvest enzymatic activities of healthy and infected Cassava (Manihot esculenta Crantz) tubers

Abstract

Post-harvest rot of tubers of three cassava (Manihot esculenta Crantz) cultivars namely TMS 4(2)1425 (hybrid cultivar); and 2 local cultivars Oko-Iyawo and Odongbo) were surveyed in Southwestern Nigeria. A total of ten fungal organisms were isolated from rotted cassava tubers collected from eight towns in four states in Southwestern Nigeria. The most frequently isolated and pathogenic ones which were used in this study as the test pathogens are Lasiodiplodia theobromae; Macrophomina phaseolina; Rhizopus stolonifer; and Fusarium pallidoroseum,. Their cell wall degrading enzymes which are cellulase; amylase; polygalacturonase (PG); and pectin methyl esterase (PME) were also assayed. In all the three cultivars inoculated with each of the test pathogens, enzyme activities were found to increase with the incubation period between 6 and 8 days of inoculation and declined at day 10. The peak of enzyme activities declined at different periods for all the cultivars used. PME and PG activities were found highest in cultivar TMS 4(2) 1425 and least in Odongbo cultivar.Test pathogens also behaved differently when inoculated with the culture filtrates of the different enzyme activities. M. Phaseolina was found highest while F. pallidoroseum was the least in all the enzyme activities cultured except in pectin methyl esterase where Lasiodiplodia theobromae had the highest activity. Mycelia dry weight of the test pathogens were also found to increase with incubation period with F. pallidoroseum having the highest mycelia mats while L. theobromae had the least. Enzyme production and activities of the test pathogens in the utilization of the carbon sources varied with the different carbon sources and the test pathogens. All the test pathogens produced enzymes and had activity but at different levels.Generally, enzyme activities showed the rate of maceration of tissues and the extent of rot disease of cassava tubers as well as the aggressiveness and pathogenic abilities of the test pathogens.

Enrichment of protein content in cassava (Manihot esculenta Crantz) by<br>supplementing with yeast for use as animal feed

“…This plant is easily grown under minimal management and it adapts to poor soil conditions, low rainfall, high temperature and pest tolerance (Salami and Akintokun, 2008). Usually, cassava is grown for root production as energy sources.…”

Procedures for evaluating the tolerance of cassava genotypes to postharvest physiological deterioration

“…Therefore, the genetic component was an important factor to explain MD severity. Salami & Akintokun (2008) reported severe MD in 'Odongbo' and 'TMS 4(2)1425', and moderate susceptibility in 'Oko-Iyawo'.…”

“…According to Salami & Akintokun (2008), the most frequently pathogens which cause MD in cassava are Lasiodiplodia theobromae, Macrophomina (1) Transformed to infection intensity index (Czermainski, 1999).…”

Revealing the antimicrobial and enzymatic potentials of culturable fungal endophytes from tropical pitcher plants (Nepenthes spp.)

“…Other endophytes produced typical enzymes that has been reported elsewhere; Phomopsis for laccase production (Vedashree et al 2013), P. simplicissimum and A. terreusfor amylase (Zeng et al 2006, Kuntal and Kumar 2012, Alhussaini 2013. Similarly, there are reports of Lasiodiplodia producing amylase (Salami andAkintokun 2008, Adejuwon 2011) but their production of tyrosinase has so far not been documented. A quick comparison with literatures revealed that amylase activities by endophytes from Nepenthes (isolate 9 and 10) were comparable to levels by endophytic Pestalotiopsis microspora strain VB5 and Aspergillus oryzae strain VB6 from mangroves (Joel & Bhimba, 2012).…”