J Integr Plant Biol. ›› 2023, Vol. 65 ›› Issue (4): 985-1002.DOI: 10.1111/jipb.13409

• Functional Omics and Systems Biology • Previous Articles     Next Articles

GhAP1-D3 positively regulates flowering time and early maturity with no yield and fiber quality penalties in upland cotton

Caixiang Wang1†, Juanjuan Liu1†, Xiaoyu Xie1, Ji Wang2, Qi Ma3, Pengyun Chen2, Delong Yang1, Xiongfeng Ma4*, Fushun Hao2* and Junji Su1,3*   

  1. 1. State Key Laboratory of Aridland Crop Science, College of Life Science and Technology, Gansu Agricultural University, Lanzhou 730070, China;
    2. State Key Laboratory of Cotton Biology, College of Life Science, Henan University, Kaifeng 475004, China;
    3. Cotton Research Institute, Xinjiang Academy of Agricultural and Reclamation Science, Shihezi 832000, China;
    4. State Key Laboratory of Cotton Biology, Institute of Cotton Research of Chinese Academy of Agricultural Sciences, Anyang 455000, China
    These authors contributed equally to this study.
    *Correspondences: Junji Su (sujj@gsau.edu.cn), Dr. Su is fully responsible for the distributions of all materials associated with this article); Fushun Hao (haofsh@henu.edu.cn); Xiongfeng Ma (maxiongfeng@caas.cn)
  • Received:2022-07-05 Accepted:2022-11-11 Online:2022-11-18 Published:2023-04-01

Abstract: Flowering time (FTi) is a major factor determining how quickly cotton plants reach maturity. Early maturity greatly affects lint yield and fiber quality and is crucial for mechanical harvesting of cotton in northwestern China. Yet, few quantitative trait loci (QTLs) or genes regulating early maturity have been reported in cotton, and the underlying regulatory mechanisms are largely unknown. In this study, we characterized 152, 68, and 101 loci that were significantly associated with the three key early maturity traits—FTi, flower and boll period (FBP) and whole growth period (WGP), respectively, via four genome‐wide association study methods in upland cotton (Gossypium hirsutum). We focused on one major early maturity‐related genomic region containing three single nucleotide polymorphisms on chromosome D03, and determined that GhAP1‐D3, a gene homologous to Arabidopsis thaliana APETALA1 (AP1), is the causal locus in this region. Transgenic plants overexpressing GhAP1‐D3 showed significantly early flowering and early maturity without penalties for yield and fiber quality compared to wild‐type (WT) plants. By contrast, the mutant lines of GhAP1‐D3 generated by genome editing displayed markedly later flowering than the WT. GhAP1‐D3 interacted with GhSOC1 (SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1), a pivotal regulator of FTi, both in vitro and in vivo. Changes in GhAP1‐D3 transcript levels clearly affected the expression of multiple key flowering regulatory genes. Additionally, DNA hypomethylation and high levels of H3K9ac affected strong expression of GhAP1‐ D3 in early‐maturing cotton cultivars. We propose that epigenetic modifications modulate GhAP1‐D3 expression to positively regulate FTi in cotton through interaction of the encoded GhAP1 with GhSOC1 and affecting the transcription of multiple flowering‐related genes. These findings may also lay a foundation for breeding early‐maturing cotton varieties in the future.

Key words: upland cotton, early maturity, genome‐wide association studies, QTL, AP1, flowering time

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