PpYUC11, a strong candidate gene for the stony hard phenotype in peach (Prunus persica L. Batsch), participates in IAA biosynthesis during fruit ripening.

Lei Pan,Wenfang Zeng,Yunqin Zhu,Weichao Fang,Weiping Li,Zhiqiang Wang,Zuguo Cai,Jinfang Chu,Hui Liu,Guohuai Li,Liang Niu,Zhenhua Lu,Guochao Cui

doi:10.1093/jxb/erv400

Abstract

High concentrations of indole-3-acetic acid (IAA) are required for climacteric ethylene biosynthesis to cause fruit softening in melting flesh peaches at the late ripening stage. By contrast, the fruits of stony hard peach cultivars do not soften and produce little ethylene due to the low IAA concentrations. To investigate the regulation of IAA accumulation during peach ripening [the transition from stage S3 to stage S4 III (climacteric)], a digital gene expression (DGE) analysis was performed. The expression patterns of auxin-homeostasis-related genes were compared in fruits of the melting flesh peach 'Goldhoney 3' and the stony hard flesh peach 'Yumyeong' during the ripening stage. It is revealed here that a YUCCA flavin mono-oxygenase gene (PpYUC11, ppa008176m), a key gene in auxin biosynthesis, displayed an identical differential expression profile to the profiles of IAA accumulation and PpACS1 transcription: the mRNA transcripts increased at the late ripening stage in melting flesh peaches but were below the limit of detection in mature fruits of stony hard peaches. In addition, the strong association between intron TC microsatellite genotypes of PpYUC11 and the flesh texture (normal or stony hard) is described in 43 peach varieties, indicating that this locus may be responsible for the stony hard phenotype in peach. These findings support the hypothesis that PpYUC11 may play an essential role in auxin biosynthesis during peach fruit ripening and is a candidate gene for the control of the stony hard phenotype in peach.

Highlights

IntroductionOf peaches is one of the most important goals of cultivar development and selection, superseded only by appearance and harvest season (Gallardo et al, 2012)
Ethylene production was low in ‘Goldhoney 3’ fruit before 110 DAFB and it sharply increased upon reaching stage S4 whereas, in ‘Yumyeong’, ethylene production was sustained at a low level during the same period (Fig. 1A)
Because indole-3-acetic acid (IAA) concentration may control ethylene production (Tatsuki et al, 2013) and, in turn, the process of fruit softening in normal flesh peaches, our study investigated the expression patterns of auxin-homeostasis-related genes in the melting flesh peach ‘Goldhoney 3’ and stony hard peach ‘Yumyeong’ during the fruit ripening stage

Summary

Introduction

Of peaches is one of the most important goals of cultivar development and selection, superseded only by appearance and harvest season (Gallardo et al, 2012). Based on the characteristics of fruit firmness and textural changes during ripening, peach cultivars can be classified into three groups: melting (M), nonmelting (NM), and stony hard (SH) flesh types (Bailey and French, 1932; Yoshida, 1976; Haji et al, 2005). Peaches of the SH type, the focus of the present study, have very firm and crisp flesh at ripening (both on- and offtree), they change colour normally and contain a high level of soluble solids (Haji et al, 2001, 2004)

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Discussion

Conclusion