Susan Zhang

All Publications

• Alkalization and cell wall remodeling mark the maturation of the fruit abscission zone in table olive JOURNAL OF EXPERIMENTAL BOTANY Wang, M., Santos, E., Eagle, S., Chernikova, A., Zhang, S., Tran, P., Marino, G., Jernstedt, J., Niederholzer, F., Wheeler-Dykes, B., Wilkop, T., Ferguson, L., Drakakaki, G. 2026

  Abstract

  Abscission zones mediate organ separation through coordinated changes in cell wall architecture and intercellular signaling. To elucidate mechanisms of fruit abscission zone (FAZ) transitions preceding fruit detachment in the non-climacteric fruit olive (Olea europaea), we integrated physiological, transcriptomic, and cellular analyses during natural maturation and after ethylene treatment. A mesocarp-subtraction RNA-seq strategy uncovered a FAZ-enriched module of 733 genes, representing core regulators of FAZ maturation. Induction of β-1,3-glucanase genes corresponded with elevated glucanase activity and callose depletion at plasmodesmata, indicating increased symplastic signaling required to initiate the abscission. A previously undocumented rise in cytoplasmic and apoplastic pH of the olive FAZ, coupled with reduction of low-methylesterified homogalacturonan, represents a hallmark of pH-dependent wall remodeling. Transcriptomic enrichment of transporters and pH-responsive wall-modifying enzymes positions pH homeostasis as a central regulator upstream of wall reconfiguration. Concurrent activation of pectate lyases and key phenylpropanoid pathway enzymes suggests a dual remodeling trajectory involving reduction of de-methylesterified pectin, which weakens intercellular cohesion, and localized lignin deposition, defining the separation boundary. Our findings establish a conserved molecular circuit that confers ethylene competence to the FAZ and a mechanistic framework in which symplastic connectivity, pH-driven enzymatic activation, and modulation of wall polymer chemistry orchestrate FAZ maturation and fruit detachment in table olive.

  View details for DOI 10.1093/jxb/erag233

  View details for Web of Science ID 001809291000001

  View details for PubMedID 42175660

• Cell layer-specific cell wall modification is associated with exo-mesocarp split in pistachio (Pistacia vera L.) JOURNAL OF EXPERIMENTAL BOTANY Zhang, S., Wang, M., Eagle, S., Chernikova, A., Bedell, K., Tran, P., Lee, C., Adaskaveg, J. A., Wei, Y., Lopez, R., Basco, A., Gordon, P., Blanco-Ulate, B., Monroe, G., Drakakaki, G. 2026

  Abstract

  Pistachio (Pistacia vera) is a drought and salinity-tolerant perennial whose fruit features a fleshy exo-mesocarp, or "hull," that protects the kernel. Hull development and degradation are key to kernel quality, yet the anatomy and mechanisms driving hull breakdown during late-stage development remain largely unknown. Here, we show that the hull contains anatomically distinct layers of hypodermal parenchyma and filler parenchyma. Using a combination of transcriptome analyses and immunohistochemistry, we show that changes in pectin associated gene expression and modification of this polysaccharide are involved in hull cell size increase, loss of cell-cell adhesion, and hull softening. Anatomical analysis shows that filler parenchyma expands during late-stage hull development while hypodermal parenchyma remains constant in size. Field data suggest that irrigation and humidity affect pistachio hull split, implicating a role for water status in cell expansion. In summary, the complex interplay between molecular, cellular, and environmental changes suggests that cell layer-specific modifications of the cell wall are linked to exo-mesocarp splitting, forming a model for understanding the mechanism of fruit split during ripening in non-berry fruit crops.

  View details for DOI 10.1093/jxb/eraf519

  View details for Web of Science ID 001656221700001

  View details for PubMedID 41327884

• Difference in Kernel Shape and Endocarp Anatomy Promote Dehiscence in Pistachio Endocarp JOURNAL OF THE AMERICAN SOCIETY FOR HORTICULTURAL SCIENCE Zhang, S., Wang, M., Chernikova, A., Eagle, S., Bedell, K., Nguyen, K., Blanco-Ulate, B., Jernstedt, J., Drakakaki, G. 2023; 148 (5): 209-+

  View details for DOI 10.21273/JASHS05324-23

  View details for Web of Science ID 001087760900002