GSE132070
MtBZR1 plays an important role in nodule development in Medicago truncatula
Brassinosteroid (BR) is an essential hormone in plant growth and development. BR signaling pathway has been extensively studied, in which Brassinazole resistant 1 (BZR1) functions as a key regulator. Here, we carried out a functional study of the homolog of BZR1 in Medicago truncatula, whose expression was induced in nodules upon rhizobial inoculation. We identified a loss-of-function mutant mtbzr1-1 and generated 35S:MtBZR1 transgenic lines for further analysis at the genetic level. Both the mutant and the overexpressor lines of MtBZR1 showed no obvious phenotypic changes under normal growth condition. After rhizobial inoculation, however, the shoot and root dry mass was reduced in mtbzr1-1 compared with the wild-type, caused by partially impaired nodule development. The transcriptomic analysis identified 1,319 differentially expressed genes in mtbzr1-1 compared with wild-type, many of which are involved in nodule development and secondary metabolite biosynthesis. Our results demonstrate an essential role of MtBZR1 in nodule development in M. truncatula, shedding light on the potential role of BR in legume-rhizobium symbiosis. Overall design: Five-day-old seedling of wild-type, mtbzr1-1, and were inoculated with 5 mL with Sinorhizobium meliloti 1021. The nodule tissue were harvested 28dpi. RNA samples were sequenced on a BGISEQ-500 platform as eukaryotes samples following the manufacturer's instructions at BGI Genomics Institute (BGI-Shenzhen, China). About 22 million raw reads were generated for each sample. Adapter sequences, low-quality reads and reads containing more than 5% unknown nucleotide were first filtered out by trimmonmatic (v0.37).