Molecular Mechanisms of Early Flowering in Tomatoes Induced by Manganese Ferrite (MnFe₂O₄) Nanomaterials.

Abstract

Nanomaterials (NMs) have demonstrated enormous potential to improve agricultural production. Ten mg L^-1 of customized manganese ferrite (MnFe₂O₄) NMs was selected as the optimal dose based on its outstanding effects on promoting tomato flowering and production. After the foliar application before flowering, MnFe₂O₄ NMs increased the leaf chlorophyll content by 20 percent, and significantly upregulated the expressions of <i>ferredoxin</i>, <i>PsaA</i>, and <i>PsbA</i> in leaves, likely by serving as an electron donor, leading to a significant increase in photosynthesis efficiency by 13.3%. Long distance transport of sucrose was then confirmed by the upregulation of sucrose transporter <i>SUT1</i> and <i>SUT2</i> in NM-treated leaves and meristems. The genes associated with gibberellin biosynthesis, including <i>GA20ox2</i>, <i>GA20ox3</i>, and <i>SIGAST</i>, and a flowering induction gene <i>SFT</i>, were also significantly upregulated. Importantly, the flowering time was 13 days earlier by MnFe₂O₄ NMs over the control. At the reproductive stage, MnFe₂O₄ NMs increased pollen activity and ovule size, leading to the significant increase in fruit number per plant, single fruit weight, and fruit weight per plant by 50%, 30%, and 75%, respectively. Metabolically, a significant increase of glucose-6-phosphate, phenylalanine, rutin, and ascorbic acid (vitamin C), as well as a significant decrease of tomatine and methionine, demonstrates an increased nutritional value of the tomato fruits. A verified companion field experiment showed an increase of 84.1% in total tomato production with the MnFe₂O₄ NM amendment. These findings provide support for the early flowering and yield improvement in nano-enabled agricultural systems.