Relation between the mating type of fungus and mycorrhizal symbiosis

通过与平菇不同菌株的共培养，研究了真菌核期和交配型对共生的影响。利用从该四极真菌单株后代中获得的4个同胞单核体和2个重组双核体。这些菌株诱导兰花种子萌发，但没有它们则不能诱导种子萌发。一个交配型亲和的单核分离物A1B1诱导了44%的种子萌发和兰花的中等生长，而另一个单核分离物A2B2只诱导了6%的种子萌发和生长非常缓慢。重组双核分离物A1B1xA2B2发芽率高，达60%以上，生长明显好于A1B1。不同交配型单核体a1b2的发芽率较高，接近90%，生长良好，而a2b1的发芽率低于2%。与A1B1xA2B2相反，另一双核体A1B2xA2B1诱导的生长速度明显慢于A1B2。结果表明：(1)A因子促进兰花种子萌发和生长，A1因子促进兰花种子萌发和生长；(2)B因子抑制兰花种子萌发和生长，且B_1抑制兰花种子萌发和生长，B_1抑制兰花种子萌发和生长，B_2促进A；同一交配型的两个单核体在兰花萌发率和生长量上存在差异，分别为44%和67%，这可能是由于核的差异所致。此外，同核不同细胞质的两个双核体在萌发上基本相同，但在生长上存在差异，这可能是由于细胞质上的差异所致。

A chlorophyll-less orchid, Erythrorchis ochobiensis, was co-cultured with different isolates of a fungus Pleurotus ostreatus, to clarity the influence of the fungus nuclear phase and mating type on their symbiosis. Four sib-monokaryons and two reconstituted dikaryons obtained from the progeny of a single strain of this tetra-polar fungus were used. These isolates induced seed germination of the orchid whereas germination was not induced without them. One monokaryotic isolate with compatible mating type, A1B1, induced 44% seed germination and moderate growth of the orchid, while the other, A2B2, induced only 6% and very slow growth. Reconstituted dikaryotic isolate, A1B1xA2B2, induced high germination rate, over 60%, with markedly better growth than A1B1. Different mating type monokaryon A1B2 induced remarkable germination, near to 90%, with satisfactory growth, whereas A2B1 induced below 2% germination. Contrary to A1B1xA2B2, another dikaryon A1B2xA2B1 induced markedly slower growth than A1B2. These results suggested that (1) factor A promotes seed germination and growth of the orchid, and factor A1 has higher promoting ability than A2, (2) factor B prohibits the germination and growth, and B1 has much prohibiting ability than B2, or (2) only B1 strongly prohibits the germination and growth, and B2 promotes the ability of A, and (3) A1B1 and A2B2 in dikaryon A1B1xA2B2 act positively and complementary for the germination and growth whereas A2B1 reduce the A1B2 effect in A1B2xA2B1. Two monokaryons of the same mating type showed difference in the germination rate, that is, 44% and 67%, and growth of the orchid, which might result from nucleic difference. Moreover, the two dikaryons with the same nuclei and different cytoplasm showed almost same in the germination but difference in the growth, which might result from cytoplasmic difference.