Categorization and scaling of distinct gossypol classes with respect to gossypol content in cotton (Gossypium hirsutum L).

Abstract

Gossypols are the pigment glands conferring resistance to insect pests; distributed on the plant body covering the stem, leaf, bract, calyx and carpel walls. The objective of the present study was to quantify the gossypol concentration on the unopened bolls of cotton and to devise a quantitative scaling for categorizing different gossypol classes in different genetic backgrounds through spectrophotometry. There were substantial differences among the P₁, P₂, F₁, F₂, BC₁ and BC₂ generations of the two crosses (HRVO-1 × Acala 63-74 and HRVO-1 × HG-142) for total gossypol and total gossypol (%). The mean total gossypol content in the glandless parent (Acala 63-74) and its F₁, in a cross with the normal glanding parent (HRVO-1) was 0.04 mg.g^-1 (2%) and 0.140 mg.g^-1 (5%) respectively while in the high glanding parent (HG-142) and its F₁ produced in a cross with the normal glanding parent it was 1.14 mg.g^-1 (46%) and 0.88 mg.g^-1 (35%) respectively. The mean total gossypol was estimated as 0.60 mg.g^-1 (24%) in the commonly used normal glanding parent. From the data and the analytical procedure used for the quantification of gossypol clearly highlighted the importance of the application of these chemo-metric tools. This method of quantification is accurate and may be used in breeding programs to screen the progeny of cotton genotypes showing segregation for gossypol content..

Keywords: Gossypium hirsutum L; Gossypol glands; Cotton Bolls; Scaling; Quantification; Spectrophotometry.