Endogenous Auxin Content Contributes to Larger Size of Apple Fruit

Haidong Bu; Wenquan Yu; Hui Yuan; Pengtao Yue; Yun Wei; Aide Wang

doi:10.3389/fpls.2020.592540

Endogenous Auxin Content Contributes to Larger Size of Apple Fruit

Front Plant Sci. 2020 Dec 3:11:592540. doi: 10.3389/fpls.2020.592540. eCollection 2020.

Authors

Haidong Bu^{1

2}, Wenquan Yu², Hui Yuan¹, Pengtao Yue¹, Yun Wei¹, Aide Wang¹

Affiliations

¹ Key Laboratory of Fruit Postharvest Biology, College of Horticulture, Shenyang Agricultural University, Shenyang, China.
² Mudanjiang Branch of Heilongjiang Academy of Agricultural Sciences, Mudanjiang, China.

Abstract

Fruit size is an important economic trait that is controlled by multiple genes. However, the regulatory mechanism for fruit size remains poorly understood. A bud sport variety of "Longfeng" (LF) apple (Malus domestica) was identified and named "Grand Longfeng" (GLF). The fruit size of GLF is larger than that of LF, and both varieties are diploid. We found that the cell size in GLF fruit was larger than that of LF. Then, we compared the fruit transcriptomes of the two varieties using RNA-Seq technology. A total of 1166 differentially expressed genes (DEGs) were detected between GLF and LF fruits. The KEGG analysis revealed that the phytohormone pathway was the most enriched, in which most of the DEGs were related to auxin signaling. Moreover, the endogenous auxin levels of GLF fruit were higher than those of LF. The expressions of auxin synthetic genes, including MdTAR1 and MdYUCCA6, were higher in GLF fruit than LF. Collectively, our findings suggest that auxin plays an important role in fruit size development.

Keywords: MdTAR1; MdYUCCA6; apple; auxin; cell size; fruit size.