The DnaJ OsDjA7/8 is essential for chloroplast development in rice (Oryza sativa)

• OsDjA7/8 is expressed in diverse tissues, predominantly in the vigorous growth leaf.
• Protein OsDjA7/8 is mainly distributed in chloroplast.
• Rice plants silenced for OsDjA7/8 exhibit defects in chloroplast development.
• Silencing OsDjA7/8 compromises the expression of the chloroplast-related genes.
• Silencing OsDjA7/8 in rice causes albino lethal at the young seedling stage.

DnaJ proteins belong to chaperones of Hsp40 family that ubiquitously participate in various cellular processes. Previous studies have shown chloroplast-targeted DnaJs are involved in the development of chloroplast in some plant species. However, little is known about the function of DnaJs in rice, one of the main staple crops. In this study, we characterized a type I DnaJ protein OsDjA7/8. We found that the gene OsDjA7/8 was expressed in all collected tissues, with a priority in the vigorous growth leaf. Subcellular localization revealed that the protein OsDjA7/8 was mainly distributed in chloroplast. Reduced expression of OsDjA7/8 in rice led to albino lethal at the seedling stage. Transmission electron microscopy observation showed that the chloroplast structures were abnormally developed in the plants silenced for OsDjA7/8. In addition, the transcriptional expression of the genes tightly associated with the development of chloroplast was deeply reduced in the plants silenced for OsDjA7/8. Collectively, our study reveals that OsDjA7/8 encodes a chloroplast-localized protein and is essential for chloroplast development and differentiation in rice.