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Article|26 May 2022|OPEN
Engineering drought-tolerant apple by knocking down six GH3 genes and potential application of transgenic apple as a rootstock
Lijuan Jiang1 ,† , Wenyun Shen1 ,† , Chen Liu1 , Muhammad Mobeen Tahir1 , Xuewei Li1 , Shuangxi Zhou2 , Fengwang Ma1 and Qingmei Guan,1 ,
1State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China
2The New Zealand Institute for Plant and Food Research Ltd, Hawke’s Bay 4130, New Zealand
*Corresponding author. E-mail: qguan@nwafu.edu.cn
Both authors contributed equally to the study.

Horticulture Research 9,
Article number: uhac122 (2022)
doi: https://doi.org/10.1093/hr/uhac122
Views: 101

Received: 09 Jan 2022
Accepted: 15 May 2022
Published online: 26 May 2022

Abstract

Drought poses a major threat to apple fruit production and quality. Because of the apple’s long juvenile phase, developing varieties with improved drought tolerance using biotechnology approaches is needed. Here, we used the RNAi approach to knock down six GH3 genes in the apple. Under prolonged drought stress, the MdGH3 RNAi plants performed better than wild-type plants and had stronger root systems, higher root-to-shoot ratio, greater hydraulic conductivity, increased photosynthetic capacity, and increased water use efficiency. Moreover, MdGH3 RNAi plants promoted the drought tolerance of the scion when they were used as rootstock, compared with wild-type and M9-T337 rootstocks. Scions grafted onto MdGH3 RNAi plants showed increased plant height, stem diameter, photosynthetic capacity, specific leaf weight, and water use efficiency. The use of MdGH3 RNAi plants as rootstocks can also increase the C/N ratio of the scion and achieve the same effect as the M9-T337 rootstock in promoting the flowering and fruiting of the scion. Notably, using MdGH3 RNAi plants as rootstocks did not reduce fruit weight and scion quality compared with using M9-T337 rootstock. Our research provides candidate genes and demonstrates a general approach that could be used to improve the drought tolerance of fruit trees without sacrificing the yield and quality of scion fruits.