Jiang Lijuan, Shen Wenyun, Liu Chen, Tahir Muhammad Mobeen, Li Xuewei, Zhou Shuangxi, Ma Fengwang, Guan Qingmei
State 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.
The New Zealand Institute for Plant and Food Research Ltd, Hawke's Bay 4130, New Zealand.
Hortic Res. 2022 May 26;9:uhac122. doi: 10.1093/hr/uhac122. eCollection 2022.
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 genes in the apple. Under prolonged drought stress, the 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, 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 RNAi plants showed increased plant height, stem diameter, photosynthetic capacity, specific leaf weight, and water use efficiency. The use of 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 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.
干旱对苹果果实生产和品质构成重大威胁。由于苹果的幼年期较长，需要利用生物技术方法培育耐旱性更强的品种。在此，我们采用RNA干扰方法在苹果中敲除了六个基因。在长期干旱胁迫下，RNA干扰植株比野生型植株表现更好，根系更强壮，根冠比更高，导水率更大，光合能力增强，水分利用效率提高。此外，与野生型和M9-T337砧木相比，RNA干扰植株用作砧木时能提高接穗的耐旱性。嫁接到RNA干扰植株上的接穗株高、茎粗、光合能力、比叶重和水分利用效率均有所增加。将RNA干扰植株用作砧木还能提高接穗的碳氮比，并在促进接穗开花结果方面达到与M9-T337砧木相同的效果。值得注意的是，与使用M9-T337砧木相比，使用RNA干扰植株作为砧木不会降低果实重量和接穗品质。我们的研究提供了候选基因，并展示了一种通用方法，可用于提高果树的耐旱性，同时不牺牲接穗果实的产量和品质。
