Mapping a major QTL responsible for dwarf architecture in Brassica napus using a single-nucleotide polymorphism marker approach

Yankun Wang,Pu Chu,Mingming Wang,Wenjing Chen,Shubei Wan,Rongzhan Guan,Mao Yang

doi:10.1186/s12870-016-0865-6

Abstract

BackgroundKey genes related to plant type traits have played very important roles in the “green revolution” by increasing lodging resistance and elevating the harvest indices of crop cultivars. Although there have been numerous achievements in the development of dwarfism and plant type in Brassica napus breeding, exploring new materials conferring oilseed rape with efficient plant types that provide higher yields is still of significance in breeding, as well as in elucidating the mechanisms underlying plant development. Here, we report a new dwarf architecture with down-curved leaf mutant (Bndwf/dcl1) isolated from an ethyl methanesulphonate (EMS)-mutagenized B. napus line, together with its inheritance and gene mapping, and pleiotropic effects of the mapped locus on plant-type traits.ResultsWe constructed a high-density single-nucleotide polymorphism (SNP) map using a backcross population derived from the Bndwf/dcl1 mutant and the canola cultivar ‘zhongshuang11’ (‘ZS11’) and mapped the dwarf architecture with the down-curved leaf dominant locus, BnDWF/DCL1, in a 6.58-cM interval between SNP marker bins M46180 and M49962 on the linkage group (LG) C05 of B. napus. Further mapping with other materials derived from Bndwf/dcl1 narrowed the interval harbouring BnDWF/DCL1 to 175 kb in length and this interval contained 16 annotated genes. Quantitative trait locus (QTL) mappings with the backcross population for plant type traits, including plant height, branching height, main raceme length and average branching interval, indicated that the mapped QTLs for plant type traits were located at the same position as the BnDWF/DCL1 locus.ConclusionsThis study suggests that the BnDWF/DCL1 locus is a major pleiotropic locus/QTL in B. napus, which may reduce plant height, alter plant type traits and change leaf shape, and thus may lead to compact plant architecture. Accordingly, this locus may have substantial breeding potential for increasing planting density.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0865-6) contains supplementary material, which is available to authorized users.

Highlights

Key genes related to plant type traits have played very important roles in the “green revolution” by increasing lodging resistance and elevating the harvest indices of crop cultivars
Molecular experiments have demonstrated that DS-1 encodes a DELLA protein in which a single proline (P) to leucine (L) substitution in the VHYNP motif leads to dwarf mutation, a gain-of-function mutation in gibberellic acid (GA) signaling [18]
Performance of the dwarf down-curved leaf mutant At the seedling stage, leaves of the Bndwf/dcl1 mutant have a sharply down-curved and crinkled phenotype, with short petioles, which contrasts with the wild-type leaves that are normal with long petioles (Fig. 1a and b)

Summary

Introduction

Key genes related to plant type traits have played very important roles in the “green revolution” by increasing lodging resistance and elevating the harvest indices of crop cultivars. The Rht (Reduced height) genes controlling a key step in the signal transduction pathway of the growth hormone gibberellic acid (GA), have been utilized worldwide, bringing about the “green revolution” in crop production [1]. A semi-dwarf gene sd that regulates a key step in the biosynthesis of GA [5,6,7] has proved extremely important in elevating harvest index and lodging resistance in worldwide rice production. The dwarf gene Bzh has an additive effect, which may bring about a greater than 30 % reduction in plant height [16, 17].

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