The genetics of jassid resistance in cotton - I. The genesH1 andH2
It has been proved by workers elsewhere that hairs of sufficient length and density, on the undersides of cotton leaves, confer immunity to jassid. The resistance of Carpulla and Tanguis, twoGossypium barbadense perennial types, is shown to be due to a basic, partially dominant, hairiness gene designated,H1, accompanied by a number of minor hairiness genes.H1 is identical with the gene previously calledHB andHtan by Harland.
The jassid resistance of MU 8b, aG. hirsutum commerical type from India, is controlled byH1 accompanied by intensifying genes which augment the effect ofH1.H1 also provides the genetic basis for the resistance found in St Ignatins, a variety ofG. hirsutum var.mariegalante from British Guiana.
Resistance in Kapas Purao was found to depend on a gene phenotypically similar toH1 accompanied by hair length intensifiers. It appears to be linked to, or possibly identical with, one of two complementary genes controlling chlorosis.
A hair density gene,H2 (identical with Harland’s,HTO), is responsible for the dense tomentum ofG. tomentosum.
Volume 100, 2021
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