Jianping Zhao, Baolin Yao, Ziai Peng, Xinyue Yang, Kuixiu Li, Xiaoyan Zhang, Haiyan Zhu, Xuan Zhou, Meixian Wang, Lihui Jiang, Xie He, Yan Liang, Xiaoping Zhan, Xiaoran Wang, Yuliang Dai, Yanfen Yang, Ao Yang, Man Dong, Suni Shi, Man Lu, Yi Zhao, Mingyun Shen, Liwei Guo, Changning Liu, Hongji Zhang, Decai Yu, Yunlong Du

Horticultural Plant Journal; Available online 3 February 2024

https://doi.org/10.1016/j.hpj.2023.11.003

Abstract

The formation of root system architecture (RSA) plays a crucial role in plant growth. OsDRO1 is known to have a function in controlling RSA in rice, however, the role of potato StDRO2, a homolog of rice OsDRO1, in root growth remains unclear. In this study, we obtained potato dro2 mutant lines by Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR-Associated 9 (CRISPR/Cas9)-mediated genome editing system. The mutant lines were generated from a splicing defect of the StDRO2 intron 1, which causes a nonsense mutation in StDRO2. Furthermore, the secondary structure of StDRO2 mRNA analyzed with RNAfold WebServer was altered in the dro2 mutant. Mutation of StDRO2 conveys potato adaptation through changing the RSA via alteration of auxin transport under drought stress. The potato dro2 lines showed higher plant height, longer root length, smaller root growth angle and increased tuber weight than the wild-type. The alteration of RSA was associated with a disturbance of IAA distribution in the dro2 mutant, and the levels of StPIN7 and StPIN10 detected by using real-time PCR were up-regulated in the roots of potato dro2 lines grown under drought stress. Moreover, the microRNAs (miRNAs) PmiREN024536 and PmiREN024486 targeted the StDRO2 gene, and auxin positively and negatively regulated the expression of StDRO2 and the miRNAs PmiREN024536 and PmiREN024486, respectively, in the potato roots. Our data shows that a regulatory network involving auxin, StDRO2, PmiREN024536 and PmiREN024486 can control RSA to convey potato fitness under drought stress.

See https://www.sciencedirect.com/science/article/pii/S2468014124000074

Fig. 7 Root phenotypes and expression levels of auxin efflux carrier genes in potato WT and dro2 mutant lines grown in the filed under normal or drought stress (A–J) Root lengths of three-month-old seedlings of wild-type ‘Li Shu 6’ (A, B) and dro2 mutant lines #1 (C, D), #2 (E, F), #3 (G, H), and #4 (I, J) grown under normal watering conditions (A, C, E, G, I) or drought stress (B, D, F, H, J). (K-P) Quantification of root lengths (K) (WT: nWater = 19, nDrought = 5; #1: nWater = 9, nDrought = 5; #2: nWater = 12, nDrought = 5; #3: nWater = 9, nDrought = 8; #4: nWater = 25, nDrought = 10) and the relative expression levels of StPIN1-StPIN10 genes in the roots of wild-type potato and dro2 mutant lines #1, #2, #3, #4 under normal watering or drought stress (L-P). The data represent at least three biological replicates. Data are means ± SD. *P < 0.05, **P < 0.01 (Student’s t-test for image K, and SPSS analysis for images L-P). ND: no difference. P1, P2, ……, P10 represents potato genes StPIN1, StPIN2,….., StPIN10. Scale bar = 1 cm.