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Article|01 Dec 2019|OPEN
PbGA2ox8 induces vascular-related anthocyanin accumulation and contributes to red stripe formation on pear fruit
Rui Zhai1, Zhigang Wang1, Chengquan Yang1, Kui Lin-Wang2, Richard Espley2, Jianlong Liu1, Xieyu Li1, Zhongying Wu3, Pengmin Li1,4, Qingmei Guan1,4, Fengwang Ma1,4 & Lingfei Xu1,
1College of Horticulture, Northwest A&F University, Taicheng Road No. 3, Yangling, Shaanxi Province, China
2The New Zealand Institute for Plant & Food Research, Ltd., (Plant and Food Research), Mt. Albert Research Centre, Private Bag, 92169 Auckland, New Zealand
3Horticultural Research Institute, Henan Academy of Agricultural Sciences, Huayuan Road No. 116, Zhengzhou, Henan Province, China
4State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Taicheng Road No. 3, Yangling, Shaanxi Province, China

Horticulture Research 6,
Article number: 19137 (2019)
doi: 10.1038/hortres.2019.137
Views: 243

Received: 22 Jul 2019
Revised: 18 Oct 2019
Accepted: 27 Oct 2019
Published online: 01 Dec 2019

Abstract

Fruit with stripes, which are generally longitudinal, can occur naturally, but the bioprocesses underlying this phenomenon are unclear. Previously, we observed an atypical anthocyanin distribution that caused red-striped fruit on the spontaneous pear bud sport “Red Zaosu” (Pyrus bretschneideri Rehd.). In this study, comparative transcriptome analysis of the sport and wild-type “Zaosu” revealed that this atypical anthocyanin accumulation was tightly correlated with abnormal overexpression of the gene-encoding gibberellin (GA) 2-beta-dioxygenase 8, PbGA2ox8. Consistently, decreased methylation was also observed in the promoter region of PbGA2ox8 from “Red Zaosu” compared with “Zaosu”. Moreover, the GA levels in “Red Zaosu” seedlings were lower than those in “Zaosu” seedlings, and the application of exogenous GA4 reduced abnormal anthocyanin accumulation in “Red Zaosu”. Transient overexpression of PbGA2ox8 reduced the GA4 level and caused anthocyanin accumulation in pear fruit skin. Moreover, the presence of red stripes indicated anthocyanin accumulation in the hypanthial epidermal layer near vascular branches (VBs) in “Red Zaosu”. Transient overexpression of PbGA2ox8 resulting from vacuum infiltration induced anthocyanin accumulation preferentially in calcium-enriched areas near the vascular bundles in pear leaves. We propose a fruit-striping mechanism, in which the abnormal overexpression of PbGA2ox8 in “Red Zaosu” induces the formation of a longitudinal array of anthocyanin stripes near vascular bundles in fruit.