Dr. Lailiang Cheng, Professor
Horticulture Section, School of Integrative Plant Science
Cornell University
Thursday March 21st, at 3:30pm, HORT 117 or via Zoom.
“Apple Flower Development and Fruit Acidity in Relation to Sorbitol”
Abstract: Apple and other tree fruits in the Rosaceae family synthesize, transport and utilize sorbitol in addition to sucrose for plant growth and development, with sorbitol being predominant. This contrasts with most other plants where sucrose serves as the sole transport sugar and appears to be adequate for plant growth and development. What role does sorbitol play in carbohydrate metabolism, plant growth and development, and stress tolerance in sorbitol-synthesizing species? In this presentation, I’ll show that sorbitol, in addition to being a carbon source, acts as a signal regulating stamen development and pollen tube growth in apple via transcription factor MYB39L. MYB39L binds to the promoter of the gene encoding a sugar transport protein, STP13a, which takes up both hexose and sucrose for pollen germination and tube growth, in response to sorbitol. I will also show that sorbitol modulates the expression of aluminum activated malate transporter 9 (ALMT9/Ma1), which underlies the Ma (malic acid) locus in apple, via a winged helix DNA binding transcription factor. At the end, I’ll briefly discuss how sorbitol signaling could be used for regulating apple tree development and stress tolerance and bigger questions on adapting apple production to a changing climate.