Formation of β-Alanine by Pine Tissues Supplied With Intermediates in Uracil & Orotic Acid Metabolism

Abstract

Aseptically removed embryos of longleaf (Pinus palustris Mill.) and slash (P. elliottii Englm.) pines and sterile callus tissue cultures of longleaf and sand [P. clausa (Chapm.) Vasey] pines were used to test the aspartic acid, the spermine-spermidine, and the pyrimidine theories of [beta]-alanine biosynthesis. Incubation of pine tissues with neither aspartic acid nor spermine nor spermidine led to accumulation of free [beta]-alanine. When experiments were designed to test the hypothesis that the sequence orotic acid[forward arrow] [forward arrow]uridine [forward arrow] [forward arrow]uracil [forward arrow] dihydrouracil[forward arrow] N-carbamyl-[beta]-alanine[forward arrow] [beta]-alanine might operate, synthesis of [beta]-alanine did occur. In each of the stepwise feeding experiments, where successive hypothetical intermediates from [beta]-alanine back to orotic acid were supplied to callus tissues and embryos, the predicted products appeared in the tissues. It is concluded that pyrimidine catabolism is an important mechanism of [beta]-alanine synthesis in the pine tissues examined.