Investigation of Pollen Source-Induced Variation in Fruit Size and Expression Pattern of Mir396a and its Target Gene During Fruit Developmental Stage in Prunus Arabica

Document Type : Research Paper

Authors

1 Department of Horticulture, Faculty of Agriculture, Shahrekored University, P.O. Box 115, Shahrekord, Iran

2 Department of Plant Breeding and Biotechnology, Faculty of Agriculture, Shahrekord University

Abstract

Objective
Almond (Prunus dulcis Mill.) represents a high-value fruit crop that is widely cultivated in temperate agro-climatic regions. Market preference and economic returns are often strongly linked to fruit size, with larger almonds generally commanding greater commercial interest. Given that the pollen parent can influence fruit characteristics, including kernel dimensions, this study applied the concept of xenia to evaluate its impact at both morphological and molecular levels, with the aim of identifying and substantiating genes involved in the regulation of fruit size.
Materials and Methods
To address this objective, Arabica almond trees were pollinated using four distinct almond genotypes: Mamaee and Pooya, characterized by large kernel size, and the Sefid cultivar along with Prunus orientalis, both producing small kernels. Fruits were sampled at multiple developmental stages and subjected to morphological and molecular assessments. Measurements of fruit length and width were obtained using a digital caliper, while fruit weight was recorded with a digital balance.
Results
Morphological analysis revealed significant differences among the crosses. Pollination with Pooya led to an increase in maternal morphological traits such as kernel length, width, thickness, and weight compared to P. orientalis. At the molecular level, the expression of Pdu-miR396a and BEN1—genes involved in plant growth and development—was examined in kernels at different developmental stages using RT-qPCR. The results showed that Pdu-miR396a expression was significantly reduced in large fruits obtained from the P. arabica × Pooya cross compared to other combinations. Moreover, its expression decreased progressively during fruit development, correlating with kernel enlargement. A negative correlation was observed between Pdu-miR396a and its target protein BRI1-5 ENHANCED 1 (BEN1), where PduBEN1 exhibited significantly higher expression in large fruits from the P. arabica × Pooya cross compared to others. These findings suggest that the Pdu-miR396a–BEN1 module potentially regulates almond kernel size through interactions between maternal and paternal parents.
Conclusion
The findings demonstrate that the Pdu-miR396a–BEN1 regulatory module is a key factor in the control of almond kernel size, with contributions from both maternal and paternal genotypes to fruit development. Accordingly, the combined use of gene expression profiling and morphological assessment offers a robust approach for supporting and verifying the influence of xenia in almond production.

Keywords

References

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Agricultural Biotechnology Journal
Volume 18, Issue 2
February 2026
Pages 1-20

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