Transcript analysis of citrus miRNA397 and its target LAC7 reveals a possible role in response to boron toxicity

• Published in: Acta physiologiae plantarum Vol. 38; no. 1
• Main Authors: Jin, Long-Fei, Liu, Yong-Zhong, Yin, Xin-Xing, Peng, Shu-Ang
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2016
• Subjects: abiotic stress; Agriculture; Biomedical and Life Sciences; biosynthesis; boron; Citrus; laccase; leaves; Life Sciences; lignin; microRNA; Original Article; Plant Anatomy/Development; Plant Biochemistry; Plant Genetics and Genomics; Plant Pathology; Plant Physiology; Poncirus trifoliata; roots; toxicity; Lignin; Trifoliate orange; Boron toxicity; miR397
• ISSN: 0137-5881; 1861-1664
• DOI: 10.1007/s11738-015-2035-0

Boron (B) toxicity reduces crop productivity and is a serious abiotic stress presenting in many parts of the world. MicroRNAs (miRNAs) play important roles in nutrient toxicity. In this study, we found that the B concentrations in roots and leaves of trifoliate orange (Poncirus trifoliata) were increased by 1.4- and 1.2-fold, respectively, after 10 days of excess B treatment (DAEBT). After 20 DAEBT, the B concentrations in roots and leaves increased by 2.8- and 2.0-fold, respectively. Transcript analysis showed that the miR397 relative transcript level decreased following the excess B treatment. Laccase7 (LAC7) was shown to be the target of miR397, and its transcription increased after the excess B treatment. In addition, the activity of laccase increased significantly following this treatment. Because LAC7 plays a role in lignin biosynthesis, we also measured the lignin concentrations in roots and leaves and found that they were increased following the excess B treatment. Our work demonstrates that decreased miR397 transcription plays a possible role in enhancing tolerance to B toxicity stress via negatively regulating LAC7 transcription and increasing the lignin concentration.