Effect of Pretreatment With Some Amino Acids and Amino Acid Antimetabolites On Longidorus Africanus-Infected and Non-Infected Bidens Tripartita

Abstract

Bur marigold plants (Bidens tripartita) were inoculated with Longidorus africanus after the nematodes were first treated with L-proline, DL-proline or DL-phenylalanine, or after the plants were dipped in L-proline, DL-proline, L-glutamic acid, DL-glutamic acid or DL-methionine. All treatments reduced root weight compared with control, more in the infected plants than in the uninfected. The ratio of tops: roots also increased after treatments. Very high ratios were obtained after pre-treatment of the uninfected and infected plants with L-glutamic acid and L-proline, respectively. The number of larvae and females increased after pretreatment of plants with L-glutamic acid and DL-methionine and decreased with DL- and L-proline. All pretreatments of nematodes brought about an increase of 35% over control in the number of larvae. The number of females increased by 17% with L-proline, 33% with DL-phenylalanine and 75% with DL-proline as compared with control. The amount of free amino acids in the roots increased in Longidorus-infected plants, especially those treated with L-proline and DL glutamic acid or infected with DL-proline-treated Longidorus. Total protein was increased in roots of plants infected with L-proline-treated nematodes. In some cases Longidorus infection greatly stimulated the growth of the plant top. It is possible that L-proline possesses therapeutic qualities and is produced in Longidorus-infected plants as a defense mechanism against the infection, and affects the rate of nematodes reproduction. No such qualities were found in the other L-amino or DL-amino acids which were used.