Ablazov Abdugaffor, Jamil Muhammad, Haider Imran, Wang Jian You, Melino Vanessa, Maghrebi Moez, Vigani Gianpiero, Liew Kit Xi, Lin Pei-Yu, Chen Guan-Ting Erica, Kuijer Hendrik N J, Berqdar Lamis, Mazzarella Teresa, Fiorilli Valentina, Lanfranco Luisa, Zheng Xiongjie, Dai Nai-Chiang, Lai Ming-Hsin, Caroline Hsing Yue-Ie, Tester Mark, Blilou Ikram, Al-Babili Salim
Center for Desert Agriculture (CDA), Biological and Environmental Sciences and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
The BioActives Lab, Biological and Environmental Sciences and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
Plant Cell Environ. 2025 Apr;48(4):2615-2629. doi: 10.1111/pce.15016. Epub 2024 Jun 26.
The rice Zaxinone Synthase (ZAS) gene encodes a carotenoid cleavage dioxygenase (CCD) that forms the apocarotenoid growth regulator zaxinone in vitro. Here, we generated and characterized constitutive ZAS-overexpressing rice lines, to better understand ZAS role in determining zaxinone content and regulating growth and architecture. ZAS overexpression enhanced endogenous zaxinone level, promoted root growth and increased the number of productive tillers, leading to about 30% higher grain yield per plant. Hormone analysis revealed a decrease in strigolactone (SL) content, which we confirmed by rescuing the high-tillering phenotype through application of a SL analogue. Metabolomics analysis revealed that ZAS overexpressing plants accumulate higher amounts of monosaccharide sugars, in line with transcriptome analysis. Moreover, transgenic plants showed higher carbon (C) assimilation rate and elevated root phosphate, nitrate and sulphate level, enhancing the tolerance towards low phosphate (Pi). Our study confirms ZAS as an important determinant of rice growth and architecture and shows that ZAS regulates hormone homoeostasis and a combination of physiological processes to promote growth and grain yield, which makes this gene an excellent candidate for sustainable crop improvement.
水稻玉米素核苷合酶（ZAS）基因编码一种类胡萝卜素裂解双加氧酶（CCD），该酶在体外可形成类胡萝卜素生长调节剂玉米素核苷。在此，我们构建并鉴定了组成型过表达ZAS的水稻株系，以更好地了解ZAS在决定玉米素核苷含量以及调节生长和株型方面的作用。ZAS过表达提高了内源玉米素核苷水平，促进了根系生长并增加了有效分蘖数，使单株籽粒产量提高了约30%。激素分析显示独脚金内酯（SL）含量降低，我们通过施用SL类似物挽救高分蘖表型对此进行了证实。代谢组学分析表明，过表达ZAS的植株积累了更多的单糖，这与转录组分析结果一致。此外，转基因植株表现出更高的碳（C）同化率以及更高的根系磷酸盐、硝酸盐和硫酸盐水平，增强了对低磷（Pi）的耐受性。我们的研究证实ZAS是水稻生长和株型的重要决定因素，并表明ZAS调节激素稳态以及一系列生理过程以促进生长和籽粒产量，这使得该基因成为可持续作物改良的优秀候选基因。
