Hibbert Lauren, Taylor Gail
School of Biological Sciences, University of Southampton, Southampton, Hampshire, RH17 7JN, UK.
Department of Plant Sciences, UC Davis, Davis, CA, 95616, USA.
Hortic Res. 2022 Feb 11;9. doi: 10.1093/hr/uhac011.
Watercress is a nutrient-dense leafy green crop, traditionally grown in aquatic outdoor systems and increasingly seen as well-suited for indoor hydroponic systems. However, there is concern that this crop has a detrimental impact on the environment through direct phosphate additions causing environmental pollution. Phosphate-based fertilisers are supplied to enhanced crop yield, but their use may contribute to eutrophication of waterways downstream of traditional watercress farms. One option is to develop a more phosphate use efficient (PUE) crop. This review identifies the key traits for this aquatic crop (the ideotype), for future selection, marker development and breeding. Traits identified as important for PUE are (i) increased root surface area through prolific root branching and adventitious root formation, (ii) aerenchyma formation and root hair growth. Functional genomic traits for improved PUE are (iii) efficacious phosphate remobilisation and scavenging strategies and (iv) the use of alternative metabolic pathways. Key genomic targets for this aquatic crop are identified as: PHT phosphate transporter genes, global transcriptional regulators such as those of the SPX family and genes involved in galactolipid and sulfolipid biosynthesis such as MGD2/3, PECP1, PSR2, PLDζ1/2 and SQD2. Breeding for enhanced PUE in watercress will be accelerated by improved molecular genetic resources such as a full reference genome sequence that is currently in development.
豆瓣菜是一种营养丰富的叶菜类作物，传统上种植于室外水生系统，如今越来越被视为适合室内水培系统。然而，有人担心这种作物通过直接添加磷酸盐造成环境污染，从而对环境产生不利影响。供应基于磷酸盐的肥料是为了提高作物产量，但其使用可能会导致传统豆瓣菜农场下游水道的富营养化。一种选择是培育一种磷利用效率更高（PUE）的作物。本综述确定了这种水生作物（理想型）未来选择、标记开发和育种的关键性状。被确定对磷利用效率重要的性状包括：（i）通过大量的根分支和不定根形成增加根表面积；（ii）通气组织形成和根毛生长。提高磷利用效率的功能基因组性状包括：（iii）有效的磷再利用和清除策略；（iv）使用替代代谢途径。这种水生作物的关键基因组靶点被确定为：PHT磷酸盐转运蛋白基因、全局转录调节因子（如SPX家族的那些调节因子）以及参与半乳糖脂和硫脂生物合成的基因（如MGD2/3、PECP1、PSR2、PLDζ1/2和SQD2）。诸如目前正在开发的完整参考基因组序列等改进的分子遗传资源，将加速豆瓣菜磷利用效率提高的育种进程。
