Posted by saikat manna

Vegetative body mycelia and consist of septate much branched hyphae. Spore on germination develop into monokaryotic or primary mycelium, either + or- typ. The primary mycelium is short lived and it soon transform into diakaryotic or secondary mycelium by the fusion of two cell of different monokaryotic mycelium following clamp connection. The hyphae of the diakaryotic mycelia interlace
twist together to form thick hyphal cord, called rhizomorph which bear the fruit bodies.
Agaricus reproduces by all the three means: vegetative, asexual and sexual.
It is mostly propagated by vegetative means where dikaryotic mycelium develops spawn, the mushroom seed. The mass spawn divides artificially into small blocks that are grown in soil supplemented with organic manure to obtain fruits bodies.
It takes place by chlamydospores that are formed rarely during unfavorable condition. Terminal or intercalary chlamydospores are developed on dikaryotic mycelium, which are on germination during favorable condition produce dikaryotic mycelium.
Stages of plasmogamy
Sex organ are absent in agaricus and sexual reproduction takes place by somatogamy. Most of the species including agaricus campestries are heterothallic. Somatogamy in includes plasmogamy, karyogamy, and meiosis. Karyogamy does not take place immediately after plasmogamy, but meiosis follows soon after karyogamy:

  1. Plasmogamy: two cells of monokaryotic hyphae of opposite strains (- or +) come in contact with each other. The cell wall dissolve at the point of contact and a dikaryon (n+n) is formed this dikaryotic cell develops into dikaryotic mycelium by regular cell divisions through clamp connection. The dikaryotic mycelia are subterranean and after aggregation at some points they form botton which remains dormant before the rain comes during late summer. After rain, the soil become soft and the button develops into fruit body. 
  2. Karyogamy: it takes place in the young basidium which develops in on gills in the fruit body. Both the nuclei fuse together and form diploid nucleus. 
  3. Growth of mycelium by clamp connection
  4. Meiosis: it takes soon after karyogamy and forms four haploid nuclei. The basidiospore, thus formed on the sterigma of basidium are haploid and either of + or – type.


Post a Comment