Amino acid constituents of inflorescence tissue of crucifers in health and disease, due to Albugo Candida (Pers.) Kuntze

Abstract

Summary There were altogether thirteen amino acids detected in radish varieties “Rainy Season Red”, “Japanese White”, “Long White” and “Local” and also in local variety of mustard. While the local varieties of radish and mustard were susceptible to Albugo Candida (Pers.) Kuntze, the other three varieties were free of disease. The amino acids found were 1-leucine/isoleucine, β -phenylalanine, valine, γ -aminobutyric acid, proline, methionine, dl-alanine, dl-threonine, glycine, glutamic acid, aspartic acid, glutamine, and homoserine. Dl-threonine, however, was absent in radish variety “Rainy Season Red”. Lower levels of 1-leucine/isoleucine, β -phenylalanine, γ -aminobutyric acid, dl-alanine, and glutamine and good quantities of methionine and homoserine were remotely connected with conferring susceptibility to the radish inflorescence against the attack of A. Candida . All these amino acids had higher amounts in disease-free varieties of radish. In disease-prone variety of both radish and mustard during pathogenesis, only quantitative and no qualitative changes in amino acid constituents were observed. Lowering in the amounts of glycine and homoserine occurred in infected tissue of both mustard and radish. Infected mustard tissue also showed decline in the amounts of leucine/isoleucine, β -phenylalanine, γ -aminobutyric acid, methionine, glutamine, glutamic acid, and aspartic acid. Their amounts, however, remained the same or increased during pathogenesis of radish tissue. Valine and proline increased in amount in mustard, but remained the same in radish during pathogenesis. While the amount of dl-alanine increased in hypertrophied radish tissue, it remained the same in mustard. A comparison of events, leading to fluctuations in amino acid constituents of the hypertrophied tissue of radish and mustard, due to one and the same pathogen, A. candida , shows that mode and modality of such variations were contradistinct to each other in the two hosts. One common feature, however, was that the amounts of almost all the amino acids was lowered in the adjacent intermediate tissue; exception being an increase in the amount of methionine in intermediate tissue of mustard.