The inheritance of yield-related traits in rapeseed (Brassica napus) is poorly understood, and the investigations on mapping of quantitative trait loci (QTL) for such traits are only few. QTL related to six traits were mapped which include plant height (PH), height of lowest primary effective branch (HPB), length of main inflorescence (LMI), silique length (SL), number of primary branches (FB) and silique density (SD). A set of 258 doubled haploid (DH) lines derivatives of a cross between a canola variety Quantum and a resynthesized B. napus line No.2127-17, and a fixed immortalized F(2) (designated as IF(2)) population generated by randomly permutated intermating of these DHs were investigated. A genetic linkage map was constructed using 208 SSR and 189 SRAP markers for the DH population. Phenotypic data were collected from three environments for the two populations. Using composite interval mapping analyses, 30 and 22 significant QTL were repeatedly detected across environments for the six traits in the DH and IF(2) populations, respectively. Twenty-nine QTL were common between the two populations. The directions of parental contribution for all common QTL were the same, showing a great potential for marker-assisted selection in improving these traits. Some chromosomal regions harbor QTL for multiple traits, which were consistent with significant phenotypic correlations observed among traits. The results provided a better understanding of the genetic factors controlling yield-related traits in rapeseed.
Cytoplasmic male sterility (CMS) in plants is a maternally inherited inability to produce functional pollen. CMS is generally caused by aberrant mitochondrial genes that are often chimeric in structure and frequently co-transcribed with conventional mitochondrial genes (Hanson and Bentolila, 2004). In many instances, male sterility can be recovered by nuclear-encoded restorer of fertility (Rf) genes. CMS/Rf systems serve as an excellent model to study mitochondrial-nuclear coevolution and interaction in plants as well as as a useful genetic tool for breeding to exploit hybrid vigor in crops (Chen and Liu, 2014). Polima (pol) CMS, initially reported in China, was the first CMS system used for commercial F 1 hybrid seed production in Brassica napus (Witt et al., 1991). The pol CMS system is associated with the presence of a chimeric open reading frame (ORF), orf224, located upstream of atp6, which encodes subunit 6 of mitochondrial ATPase (Singh and Brown, 1991;L'Homme and Brown, 1993). In the presence of the nuclear restorer gene, Rfp, processing of orf224/atp6 RNA is affected and its transcripts are specifically altered, which suggests that orf224 is the causal gene of pol CMS (Singh and Brown, 1991). A previous comparison of RNA-seq data between fertile and sterile young flower buds with pol CMS suggested that energy deficiency caused by orf224/atp6 may inhibit a series of genes that regulate pollen development via nuclear-mitochondrial interactions (An et al., 2014). However, how orf224/atp6 causes male sterility and how Rfp conditions orf224/atp6 transcription remain unclear. Answering both questions would represent an important step in characterizing Rfp.
Accumulated evidence has shown that each of the three basic Brassica genomes (A, B and C) has undergone profound changes in different species, and has led to the concept of the "subgenome". Significant intersubgenomic heterosis was observed in hybrids between traditional Brassica napus and first generation lines of new type B. napus. The latter were produced by the partial introgression of subgenomic components from different species into B. napus. To increase the proportion of exotic subgenomic components and thus achieve stronger heterosis, lines of first generation new type B. napus were intercrossed with each other, and subjected to intensive marker-assisted selection to develop the second generation of new type B. napus. The second generation showed better agronomic traits and a higher proportion of introgression of subgenomic components than did the first generation. Compared with the commercial hybrid and the hybrids produced with the first generation new type B. napus, the novel hybrids showed stronger heterosis for seed yield during the 2 years of field trials. The extent of heterosis showed a significant positive correlation with the introgressed subgenomic components in the parental new type B. napus. To increase the content of the exotic subgenomic components further and to allow sustainable breeding of novel lines of new type B. napus, we initiated the development of a gene pool for new type B. napus that contained a substantial amount of genetic variation in the A(r) and C(c) genome. We discuss new approaches to broaden the avenue of intersubgenomic heterosis in oilseed Brassica.
A novel cytoplasmic male sterility (CMS) was identified in Brassica juncea, named as hau CMS (00-6-102A). Subsequently, the male sterility was transferred to B. napus by interspecific hybridization. The hau CMS has stable male sterility. Flowers on the A line are absolutely male sterile, and seeds harvested from the line following pollinations with the maintainer gave rise to 100% sterile progeny. The anthers in CMS plants are replaced by thickened petal-like structures and pollen grains were not detected. In contrast, in other CMS systems viz. pol, nap, tour, and ogu, anthers are formed but do not produce viable pollen. The sterility of hau CMS initiates at the stage of stamen primordium polarization, which is much earlier compared with the other four CMS systems. We have successfully transferred hau CMS from B. juncea to B. napus. Restorer lines for pol, ogu, nap, and tour CMS systems were found to be ineffective to restore fertility in hau CMS. Sixteen out of 40 combinations of mitochondrial probe/enzyme used for RFLP analysis distinguished the hau CMS system from the other four systems. Among these sixteen combinations, five ones alone could distinguish the five CMS systems from each other. The evidence from genetic, morphological, cytological and molecular studies confirmed that the hau CMS system is a novel CMS system.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.