Fu Tingdong

Detection of QTL for six yield-related traits in oilseed rape (Brassica napus) using DH and immortalized F2 populations

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 F2 (designated as IF2) 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 IF2 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.

Growth and Yield Formation of Direct-Seeding Rapeseed Under No-Tillage Cultivation in Double Rice Cropping Area in Hubei Province

Abstract In the Yangtze River basin, winter fallow is popular for the double cropping rice (Oryza sativa L.). In this study, the possibility of adding a rapeseed cropping season after late rice harvest in this area was studied with the purpose of extending direct-seeding rapeseed under no-tillage cultivation pattern. In a 2-year field experiment from 2008 to 2010, the rapeseed cultivar Huashuang 5 (Brassica napus L. cv. Huashuang 5) were planted in 3 locations in Hubei Province of China after harvesting late rice. At both individual and population levels, the effects of plant density and nitrogen (N) application rate on rapeseed growth and yield formation were measured at seedling, budding, flowering, podding, and maturity stages. The cultivation pattern of no-tillage and direct-seeding after late rice harvest shortened the growth duration of rapeseed, especially at seedling stage, but prolonged the late budding stage in spring. The biomass accumulation from emergence to early budding was deficient severely, resulting in quick growth from budding to flowering of rapeseed. Application of N fertilizer had significant effects on enhancing the growth and yield formation of rapeseed through improving the individual and population qualities. Under the N rate of 270 kg ha−1 condition, the highest yield of rapeseed was approximately 2250 kg ha−1 at the density of 4.5 × 105 plants or 6.0 × 105 plants per hectare. The yield level was higher than that of average local rapeseed production. In the practice of no-tillage and direct seeding cultivation technique in the double rice cropping rice area, both nitrogen application rate and planting density should be considered simultaneously to obtain high quality of plant population and high yield of rapeseed.

Recessive Genic Male Sterility in Brassica napus and Its Application

The Brassica napus recessive genic male sterile (RGMS) line was widely used in heterosis utilization because it possesses stable sterility, no negative cytoplasmic effects, easy restoration and multi-restored resources. There are mainly two recessive genic male sterile lines in China. One is controlled by two duplicate recessive genes, and another is controlled by two loci, one recessive mutant locus and one multiple allele locus. With cloning of these sterile genes, some molecular mechanisms of genic male sterility in Brassica napus was deciphered. In this review, we summarize the advances in research on molecular mechanism of genic male sterility in Brassica napus . A feasible way is proposed to breed entire sterile populations of genic male sterile line in Brassica napus , which shows broad prospects in heterosis utilization.