Cultivation And Molecular Characterisation Of Auricularia Species In Southwestern Nigeria

ABSTRACT

Mushrooms such as Pleurotus, Vovariella and Auricularia species are

cultivated for food and medicinal purposes in the world. However, cultivation of

Auricularia in Nigeria is limited due to inadequate information on its characteristics,

nutritional contents and cultivation requirements. Hence, this study was designed to

characterise Auricularia species in Southwestern Nigeria and determine suitable

substrates for their cultivation.

Fifty-four samples of Auricularia species were randomly collected based on

availability from secondary forests in Osun (11), Oyo (10), Ondo (9), Ekiti (8), Ogun

(8) and Lagos States (8). Pieces of tissue from each sample were cultured on Potato

Dextrose Agar (PDA). Samples with mycelial growth were later cultured on sterilised

sorghum grains to produce spawns. Six substrates comprising Mansonia altissima. (A.

Chev) A. Chev sawdust, cotton waste Gossypium hirsutum Linn, rice straw Oryza

sativa Linn, each in polyethylene bags and drilled logs of Mangifera indica Linn,

Gliricidia sepium (Jacq) Walp, and Cedrela odorata Linn, were purposively selected

for spawn inoculation to produce mushrooms. Morphological identification (colour,

shape and texture) of Auricularia species, the growth parameters (days of spawn run,

days of pin head formation), and yield of the mushrooms were determined using

standard procedures. Nutrient (nitrogen, phosphorus, and potassium) and proximate

analysis (Protein, Fat, and Carbohydrate) were carried out using AOAC methods.

Fifteen Random Amplified Polymorphic DNA (RAPD) primers were used for PCR

amplification of the DNA of Auricularia samples, to determine the degree of genetic

diversity. Phylogenetic relations were determined by cluster analysis, Polymorphic

Information Content (PIC) and genetic diversity determined using standard

procedures. Data were analysed using descriptive statistics, clustering and Principal

Component Analyses (PCA).

UNIVERSITY OF IBADAN LIBRARY

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Morphologically, 31 samples of A. auricula, (yellow brown, auriform, leathery

texture) and 12 samples of A. polytricha (dark brown, discoid, gelatinous) were

identified, while 5 samples were unidentified and 6 samples did not grow. Auricularia

species samples cultivated on M. altissima sawdust, cotton waste, rice straw in bags

produced mycelial growth, but did not fructify while samples on drilled logs had

mycelial growth and fructified. Mangifera indica had highest days of spawn run

(24.3±0.7), pin head formation (28.7± 0.6) and highest yield (10.0±0.4 g). The highest

nitrogen content (13.6 ±0.7 mg/kg) was recorded in A. polythrica, phosphorus

(39.3±7.6 mg/kg) in A. auricula and calcium (61.9 ± 3.6 mg/kg) in A. auricula. The

highest protein (7.0±0.8%) and crude fibre (25.1±2.5%) were obtained in A.

polythrica. Fat content (7.0 ± 0.1mg/kg) was highest in A. auricula. Cluster analysis

and morphological traits produced 6 distinct groups while the PCA produced

eigenvalues of 23.0 %, 16.0 %, 14.0 %, 11.0 %, 10.0 % and 9.0 % on six

corresponding axes. The RAPD primers grouped the Auricularia species into 6

distinct clusters based on morphological traits. The PIC ranged from 0.5594 (OPH-

15) to 0.7819 (OPB-12) and gene diversity from 0.5930 (OPH-15) to 0.7977 (OPB-

12). Primer OPB-12 was the most informative for genetic diversity of Auricularia

species.

Auricularia species exhibited genetic variations and Mangifera indica

enhanced their growth. Auricularia polytricha was the most nutritious species

recorded.

Keywords: Mushroom cultivation, Mangifera indica substrate, Polymorphic

information content.