Influence of Jasmonates, Salicylic Acid and 24-Epibrassinolide on Other Plant Growth Regulators during Development and Germination in the Recalcitrant Seeds of Artocarpus hirsutus Lam.

Artocarpus hirsutus Lam. is a tropical, endemic, keystone tree species of the Western Ghats commercially utilized for its valuable timber. The seeds are reported to be recalcitrant, but its exact physiology and the hormonal changes during development and germination has not been well studied. The present study was intended to understand the hormonal dynamics and their interaction to get an idea about the up and down regulation during seed development and germination. Fifteen hormones were simultaneously analyzed using LC MS/MS technique. Our results showed that during histodifferentiation IAA, GA4, cytokinins (tZ and tZR), JA and 24-epibrassinolide (24-epiBL) were found in higher levels, but during seed expansion all these plant hormones began to decrease. However salicylic acid and cis jasmone were found elevated during germination. Like other recalcitrant seeds ABA was found in higher level during early embryogeny but declined sharply in the later embryogeny and germination. JA showed strong positive correlation with IAA (0.997**), ABA (0.955*), tZ (0.997**) and tZR (0.975*) possibly acts as an inducer of all these hormones, but no significant relationship with other hormones. However SA, which was found in extremely higher level during development and germination, did not show any significant relationship with other hormones, possibly functioning in defense mechanism. 24-epiBL was found in significant level, but showed insignificant relationship with hormones. Natural desiccation had a negative impact on the synthesis/accumulation of PGRs. Electrical conductivity studies revealed that cell membrane damage of the embryonic tissue was responsible for the loss of viability of these recalcitrant seeds. [ABSTRACT FROM AUTHOR]