The nitrogen metabolism of the Kelsey plum

Abstract

THE nitrogenous changes in mature Kelsey plums during storage appear to differ fundamentally from those in the apple. The most striking feature of the nitrogen metabolism of the apple is its phase of net synthesis of protein during the final stage of development on the tree [Hulme, 1936]. This drift towards protein synthesis is also characteristic of "mature ", detached apple-fruits [Hulme, 1932]. Mature Kelsey plums, on the other hand, show a distinct drift towards protein breakdown when stored at either 35 or 700 F. [Donen, 1937, 2]. Hulme [1935] has shown, however, that the nature of protein changes in the stored apple depends upon its stage of physiological development: thus " young " apples display the same characteristics as "mature" plums and on storage at 1 or 120 C. show protein breakdown. It is possible then that the nitrogenous changes in the plum during its full development to maturity do not proceed further than the stage corresponding to "young" fruit in the apple. The most important steps in the nitrogen cycle of the growing plum have therefore been ascertained and are presented in this paper. EXPERIMENTAL Material and method of sampling. Two series of samples were collected. The object was to gauge whether fruit collected from trees grown under different environmental and cultural conditions showed any marked variation in the relationship between the estimated nitrogenous compounds. Series I. The fruit was collected from 14 Kelsey trees worked on peach stock at Elgin, Cape. The trees were 9 years old and somewhat stunted in growth. Soil pebbly and poorly weathered. Petal fall on

Development and metabolism of the fruit and seed of the Japanese plum Ozark premier (Rosaceae)

“…5). A similar pattern of changes in the content of total N was observed in the endocarp and seed of Kelsey plum during development (Donen, 1938). The very low content of protein in the endocarp after about 100 DAB was not a result of a loss of protein during extraction because co-extraction with endocarp from 68 DAB did not result in a loss of protein (data not shown).…”

“…1). This timing of growth of the endocarp and flesh is similar to that observed previously in plum (both cultivars of P. domestica and Japanese plum) and mid and late season varieties of peach and cherry (Lilleland, 1933;Lilleland and Newsome, 1935;Donen, 1938;Pavel and Dejong, 1993a;Walker et al, 2011a). The lignification of the endocarp of these stone fruits commences when it approaches its maximum size at the end of stage I.…”

“…This raises the possibility that glutamine is more readily utilized than asparagine in the flesh of these fruits, as in developing soybean seeds, in which asparagine accumulates (Skokut et al, 1982;Micallef and Shelp, 1989). On a per fruit basis, amide accumulates during stage III in Kelsey plum flesh, and the amount of nitrogen in this is about double that in protein in ripe flesh (Donen, 1938). This amide is likely to be asparagine (Komiyama et al, 1978;Van Gorsel et al, 1992).…”

“…This shows that there was protein synthesis. Similarly, proteins are synthesized in the flesh of Kelsey plum during stage III (Donen, 1938). Asparagine is a major form of transported nitrogen in the Japanese plum cultivar Methley (Andersen et al, 1995a), and is abundant in plum flesh (Burroughs, 1971;Komiyama et al, 1978;Van Gorsel et al, 1992).…”

“…The utilization of aspartate and NH 4 + produced by asparaginase does not always occur at the same time, and NH 4 + can accumulate (Skokut et al, 1982). In the flesh of Kelsey plum NH 4 + is abundant until stage III and accounts for about 20% of the soluble nitrogen content of the pulp (Donen, 1938). In this situation AspAT may be necessary for the conversion of aspartate to glutamate (Skokut et al, 1982).…”