Exploring the phytohormonal crosstalk during embryonic journey and germination process of Vateria indica L. seeds utilizing LCMS/MS technology

Abstract

Vateria indica L. is an endangered tree species indigenous to South Western-Ghats regions of India, which is of immense economic importance. The natural regeneration process of this species is hindered by many factors including seed recalcitrance, which is a major problem hindering its natural regeneration, thus posing a great challenge in its seed storage and conservation. Recalcitrant seeds show marked differences from orthodox seeds in development. The onset of different stages is marked by a definite peaking and lowering of phytohormones and this hormonal pattern varies in orthodox and recalcitrant seeds. Phytohormonal dynamics in recalcitrant seeds, is a poorly investigated area and the present investigation was undertaken with a view to understand the hormonal changes during embryogeny and germination in this recalcitrant species. We have tested fifteen plant growth regulators simultaneously to get a better understanding about their role in embryogeny and germination. During April–July 2020, seeds were collected from their native habitats in the South Western-Ghats. From the randomly selected seeds, the embryonic tissues were chopped and frozen for LC–MS/MS hormonal profiling. The triplet hormonal interplay (between auxin, cytokinin and gibberellins) was found to be very crucial for the development of the embryo in Vateria indica L. In the present study, we can see a clear antagonism of cis Jasmonate with Brassinosteroid, cis Jasmonate declining during seed shed (14.44 ± 0.39 ng g-1fw) and germination phases, while Brassinosteroid increasing during these phases (32.24 ± 1.69 ng g-1fw). A clear hormonal interplay can also be seen between Auxin (Indole-3 Butyric acid—45.44 ± 0.3 ng g-1fw) and Brassinosteroid (24epi-Brassinolide—32.24 ± 1.69 ng g-1fw) at the time of seed germination. Phytohormone interplay and crosstalk provides an emerging knowledge about connections between phytohormones which are pivotal for growth and development and even stress responses in plants.

Graphical abstract

Chromatogram of Phytohormones.

Chromatogram of Phytohormones -X axis represents time and Y axis represents absorbance A, B and C—In Negative mode (ES-): Salicylic acid, IAA, IBA, JA, Benzene Adenine, ABA, GA-7, GA-4, GA-3, Epibrassinolide. D, E and F—In Positive mode (ES +): ACC, Cis-Jasmonate, Zeatin, Methyl Jasmonate and Trans Zeatin Riboside.

Chromatogram of Phytohormones. X axis represents time and Y axis represents absorbance D and E—In Negative mode (ES-): Salicylic acid, IAA, IBA, JA, Benzene Adenine, ABA, GA-7, GA-4, GA-3, Epibrassinolide. I and J—In Positive mode (ES +): ACC, Cis-Jasmonate, Zeatin, Methyl Jasmonate and Trans Zeatin Riboside.