Kejia Zhang, Wei Gao, Yimei Zhou, Haoshun Zhao, Yuelin Xia, Mengyi Zhang, Yongming Bo, Xiaolong Lyu, Zhongyuan Hu, Jinghua Yang & Mingfang Zhang

Theoretical and Applied Genetics September 2023; vol. 136, Article number: 199

Key message

The ClACO gene encoding 1-aminocyclopropane-1-carboxylate oxidase enabled highly efficient ¹⁵N uptake in watermelon.

Abstract

Nitrogen is one of the most essential nutrient elements that play a pivotal role in regulating plant growth and development for crop productivity. Elucidating the genetic basis of high nitrogen uptake is the key to improve nitrogen use efficiency for sustainable agricultural productivity. Whereas previous researches on nitrogen absorption process are mainly focused on a few model plants or crops. To date, the causal genes that determine the efficient nitrogen uptake of watermelon have not been mapped and remains largely unknown. Here, we fine-mapped the 1-aminocyclopropane-1-carboxylate oxidase (ClACO) gene associated with nitrogen uptake efficiency in watermelon via bulked segregant analysis (BSA). The variations in the ClACO gene led to the changes of gene expression levels between two watermelon accessions with different nitrogen uptake efficiencies. Intriguingly, in terms of the transcript abundance of ClACO, it was concomitant with significant differences in ethylene evolutions in roots and root architectures between the two accessions and among the different genotypic offsprings of the recombinant BC₂F₁(ZJU132)-18. These findings suggest that ethylene as a negative regulator altered nitrogen uptake efficiency in watermelon by controlling root development. In conclusion, our current study will provide valuable target gene for precise breeding of ‘green’ watermelon varieties with high-nitrogen uptake efficiencies.

See https://link.springer.com/article/10.1007/s00122-023-04448-1

Fig. 3. Boxplot showing the variability of four root morphological traits [(A) total root length (TRL), (B) average root diameter (ARD), (C) total root surface area (TSA), and (D) total root volume (TRV)] across four species of Citrullus as evaluated under greenhouse conditions. CA = Citrullus amarus; CC = Citrullus colocynthis; CL = Citrullus lanatus; CM = Citrullus mucosospermus.