Abstract
Oilseed rape (Brassica napus L.) is the second largest oilseed crop worldwide and one of the most important oil crops in China. As a component of plant architecture, branch angle plays an important role in yield performance, especially under high-density planting conditions. However, the mechanisms underlying the regulation of branch angle are still largely not understood. Two oilseed rape lines with significantly different branch angles were used to conduct RNA- and miRNA-profiling at two developmental stages, identifying differential expression of a large number of genes involved in auxin- and brassinosteroid (BR)-related pathways. Many auxin response genes, including AUX1, IAA, GH3, and ARF, were enriched in the compact line. However, a number of genes involved in BR signaling transduction and biosynthesis were down-regulated. Differentially expressed miRNAs included those involved in auxin signaling transduction. Expression patterns of most target genes were fine-tuned by related miRNAs, such as miR156, miR172, and miR319. Some miRNAs were found to be differentially expressed at both developmental stages, including three miR827 members. Our results provide insight that auxin- and BR-signaling may play a pivotal role in branch angle regulation.
Highlights
Rapeseed is one of the most important oil crops for a large part of the world
Amongst all plant architecture traits, leaf angle or branch angle has been demonstrated to be essential for high-density planting [2,3]
Samples from the branch emergence site collected at both bolting and early flowering were subjected to transcriptome sequencing (Illumina HiSeq2000, Illumina, San Diago, CA, USA) generating ~46.86 million and ~45.36 million raw reads from 6098B and Purler, respectively
Summary
Rapeseed is one of the most important oil crops for a large part of the world. In the context of decreasing arable lands and increasing population, maximizing the yield potential of crops is a principal goal for plant breeders. Remarkable progress has been made regarding the identification of quantitative trait loci (QTL) and genes for tiller or leaf angle over the last few decades Those identified in rice include LAZY1, TILLER ANGLE CONTROL1, PROSTRATE GROWTH1, and LOOSE PLANT ARCHITECTURE1 [9,10,11,12]. Changes in the expression levels of genes involved in auxin synthesis or signaling transduction have been shown to result in differences in the tiller angle and gravitropic response [8]. Multiple studies have shown the importance of miRNA regulation of corresponding target genes in a wide range of plant developmental processes. MiR319, which is known to target TCP (TEOSINTE-BRANCHED/CYCLOIDEA/PCF) transcription factors, has been shown to regulate leaf development and morphogenesis by controlling the plant organ fate [20]. Our results provide further insight into the putative role of auxin- and BR-related genes in branch angle regulation
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