Rapid burst of ethylene evolution by premature seed: A warning sign for the onset of spongy tissue disorder in Alphonso mango fruit?

ABSTRACT

Moisture stress induced in premature seeds due to the breakdown of funiculus in Alphonso mango led to the burst ofethylene evolution, which in turn caused a sudden increase of polyphenol oxidase activity in the pulp, resulting in thedevelopment of a black spot near the seed base. Reduced levels of very long chain fatty acids in 70% mature seeds withblack spots were associated with a sudden increase of cytokinins followed by a rapid rise of starch-metabolizing enzymesculminating in the onset of pre-germination events. Concurrently, an overproduction of p-OH benzoic acid inhibitedamylase and polygalacturonase enzymes and led to partial degradation of the stored starch and pectin in the pulp. A paralleldrop in climacteric ethylene production by the pulp led to incomplete ripening coupled with changes in composition, textureand aroma of the pulp, characteristic of spongy tissue. The results have provided strong experimental evidence to supportthe fact that increased competition for resources among developing fruits for the synthesis of seed fat plays a critical role inspongy tissue formation in Alphonso mango. The major highlight of the study is that rapid ethylene evolution by prematureseed is an early warning sign for the initiation of spongy tissue formation in Alphonso mango.