Negi Manisha, Sanagala Raghavendrarao, Rai Vandna, Jain Ajay
National Research Centre on Plant Biotechnology, Lal Bahadur Shastri Building New Delhi, India.
Front Plant Sci. 2016 May 4;7:550. doi: 10.3389/fpls.2016.00550. eCollection 2016.
Phosphate (Pi), an essential macronutrient for growth and development of plant, is often limiting in soils. Plants have evolved an array of adaptive strategies including modulation of root system architecture (RSA) for optimal acquisition of Pi. In rice, a major staple food, RSA is complex and comprises embryonically developed primary and seminal roots and post-embryonically developed adventitious and lateral roots. Earlier studies have used variant hydroponic systems for documenting the effects of Pi deficiency largely on primary root growth. Here, we report the temporal effects of Pi deficiency in rice genotype MI48 on 15 ontogenetically distinct root traits by using easy-to-assemble and economically viable modified hydroponic system. Effects of Pi deprivation became evident after 4 days- and 7 days-treatments on two and eight different root traits, respectively. The effects of Pi deprivation for 7 days were also evident on different root traits of rice genotype Nagina 22 (N22). There were genotypic differences in the responses of primary root growth along with lateral roots on it and the number and length of seminal and adventitious roots. Notably though, there were attenuating effects of Pi deficiency on the lateral roots on seminal and adventitious roots and total root length in both these genotypes. The study thus revealed both differential and comparable effects of Pi deficiency on different root traits in these genotypes. Pi deficiency also triggered reduction in Pi content and induction of several Pi starvation-responsive (PSR) genes in roots of MI48. Together, the analyses validated the fidelity of this modified hydroponic system for documenting Pi deficiency-mediated effects not only on different traits of RSA but also on physiological and molecular responses.
磷（Pi）是植物生长发育必需的大量营养素，但在土壤中往往含量有限。植物已经进化出一系列适应性策略，包括调节根系结构（RSA）以实现对磷的最佳吸收。在主要主食作物水稻中，根系结构复杂，包括胚胎发育形成的初生根和种子根以及胚后发育形成的不定根和侧根。早期研究使用不同的水培系统记录了缺磷主要对初生根生长的影响。在此，我们通过使用易于组装且经济可行的改良水培系统，报告了水稻基因型MI48中缺磷对15个发育阶段不同的根系性状的时间效应。缺磷处理4天和7天后，分别对两种和八种不同的根系性状产生了明显影响。缺磷7天对水稻基因型Nagina 22（N22）的不同根系性状也有明显影响。在初生根生长以及其上的侧根、种子根和不定根的数量和长度方面，不同基因型的反应存在差异。然而，值得注意的是，缺磷对这两种基因型的种子根和不定根上的侧根以及总根长都有减弱作用。因此，该研究揭示了缺磷对这些基因型不同根系性状的差异和可比效应。缺磷还导致MI48根系中磷含量降低，并诱导了几个磷饥饿响应（PSR）基因。综合分析验证了这种改良水培系统不仅能忠实记录缺磷对根系结构不同性状的影响，还能记录其对生理和分子反应的影响。
