Arabidopsis NAP-related proteins (NRPs) contribute to the coordination of plant growth, developmental rate, and age-related pathogen resistance under short days. Arabidopsis thaliana

Plant nucleosome assembly protein-related proteins (NRPs) are histone chaperons involved in nucleosome turnover. Despite this basic cellular function, the Arabidopsis nrp1-1 nrp2-1 knock out mutant has been reported to exhibit only relatively mild seedling root phenotypes and to significantly affect the expression of only few hundred genes (Zhu et al., 2006). Here we report that NRP loss-of-function as well as the ectopic overexpression of At NRP1 significantly affected the growth, development, and the pathogen response of Arabidopsis plants under short day conditions. The nrp1-1 nrp2-1 mutant grew faster and flowered weeks earlier than the wild type and the overexpressor. The latter developed slower and flowered at a lower number of leaves than the mutant and the wild type. Moreover, the mutant was more sensitive, the overexpressor was more tolerant to pathogen infection correlating with their more adult and juvenile character, respectively. Transcriptomic comparison of mature non-bolting plants agreed with the phenotypes. The presented and published data indicate that although NRPs might not be absolutely required for plant growth and development, they contribute to the epigenetic coordination of metabolic, growth, defence and developmental processes during adaptation. Overall design: Three groups of Arabidopsis thaliana samples (nrp1-1 nrp2-1 double mutant, wild-type, NRP1 overexpressor), each containing two biological replicates were included in the study

核小体组装蛋白相关蛋白（nucleosome assembly protein-related proteins，NRPs）是参与核小体周转的组蛋白伴侣蛋白。尽管具备此类基础细胞功能，但已有研究显示，拟南芥nrp1-1 nrp2-1双敲除突变体仅表现出相对轻微的幼苗根系表型，且仅对数百个基因的表达产生显著调控影响（Zhu等，2006）。
本研究发现，在短日照条件下，NRP功能缺失以及拟南芥AtNRP1的异位过表达，均会显著影响拟南芥的生长发育与病原体响应过程。与野生型及过表达株系相比，nrp1-1 nrp2-1突变体生长速度更快，开花时间提前数周；而过表达株系则生长更为迟缓，开花时的叶片数较突变体与野生型更少。此外，该突变体对病原体侵染更为敏感，过表达株系则耐受性更强，二者的这种响应差异分别与其成体与幼体的性状特征相契合。
对成熟未抽薹植株的转录组比较分析结果与上述表型相一致。
本研究所得及已发表的数据均表明，尽管NRPs可能并非植物生长发育所绝对必需，但它们在植物适应过程中，参与了代谢、生长、防御与发育进程的表观遗传调控协调。
实验整体设计：本研究共纳入三组拟南芥（Arabidopsis thaliana）样本，分别为nrp1-1 nrp2-1双敲除突变体、野生型株系以及NRP1过表达株系，每组均包含两个生物学重复。