H.-J. Wiebe

Bio: H.-J. Wiebe is an academic researcher. The author has contributed to research in topics: Flower formation & Vernalization. The author has an hindex of 1, co-authored 1 publications receiving 28 citations.

A naturally occurring long insertion in the first intron in the Brassica rapa FLC2 gene causes delayed bolting

Abstract: We investigated the molecular basis of an extremely late bolting, non-heading ‘Leafy Green Parental Line No. 2 (Tsukena No. 2)’, to obtain suitable DNA markers for breeding the late bolting trait in Chinese cabbage (Brassica rapa L. ssp. pekinensis). We found that Tsukena No. 2 contains a ~5 kbp large insertion near the 5′ end of the first intron of BrFLC2, BrFLC3 and BrFLC3′, which are homologs of an Arabidopsis repressor gene for floral transition, FLOWERING LOCUS C (FLC). The transcript abundance of BrFLC1 in Tsukena No. 2 was repressed during cold exposure to the same level as found in a mid-season bolting commercial F1 variety “Muso” (heading Chinese cabbage) and an early-bolting parent of commercial F1 varieties, “Early” (Sakata Co.), whereas repression of BrFLC2 and BrFLC3 containing the large insertion was weak. Furthermore, QTL analysis of a F2 population derived from the Tsukena No. 2 × “Early” revealed that polymorphisms at the BrFLC2 and BrFLC3 loci explained 46.0 and 9.9 % of the phenotypic variation in the bolting time of vernalized plants, respectively. In Arabidopsis, cold-induced repression of FLC and maintenance of that repression are associated with the first intron of FLC. Our study suggests that a naturally occurring large insertion in the first intron resulted in weak repression of BrFLC2 and BrFLC3 during cold exposure and therefore explains the extremely late bolting of the Tsukena No. 2 cultivar.

Identification and mapping of a quantitative trait locus controlling extreme late bolting in Chinese cabbage (Brassica rapa L. ssp. pekinensis syn. campestris L.) using bulked segregant analysis.

Abstract: DNA markers linked to a locus controlling an extreme late bolting trait, which was originally found in a local cultivar of a non-heading leafy vegetable,‘Osaka Shirona Bansei’ (Brassica rapa L. ssp. pekinensis syn. campestris L.) were identified using bulked segregant analysis. A doubled haploid (DH) line, DH27, which is a progeny of ‘Osaka Shirona Bansei’, shows extreme late bolting, and bolts without vernalization. DH27 was crossed with a normal bolting DH line, G309. The plantlets of the parents, F1 and F2, were vernalized and then grown in a greenhouse. The bolting time of F2 plants showed a continuous distribution from 19 to 231 days after vernalization (DAV), suggesting the effects of a few major genes and polygenes. Possible linkage markers for this trait were screened by modified bulked segregant analysis (BSA). The BSA using four bulks suggested that a 530-bp RAPD band RA1255C was linked to a locus controlling the bolting trait. The RAPD band was cloned and used as a probe to detect RFLP. The fragment detected a single locus, BN007-1,the segregation of which in the F2 population matched that of RA1255C. Three other RAPDs were found to be linked to BN007-1. A quantitative trait locus(QTL) affecting the bolting time was detected around BN007-1 using MAPMAKER/QTL. Since the difference between bolting times of both the parental genotypes in the F2 was 138 days, these markers may be useful for a marker-assisted selection (MAS) in the breeding program for late bolting or bolting-resistant cultivars in B. rapa crops.

Manipulation of bolting and flowering in celery (Apium graveolens L. var. dulce). II. Juvenility.

Abstract: SummaryAfter germination, a juvenile phase of development was apparent in cvs New Dwarf White and Celebrity. During this incompetent phase, plants were not induced flower even when subjected to chilling at 5°C for nine weeks. Juvenility ended and the plants became competent to perceive chilling as a vernalization stimulus when they had initiated 17 leaves including leaf primordia in cv. New Dwarf White and between 17 and 20 leaves in cv. Celebrity. After phase transition, the level of competence was not affected by plant age. The rate of leaf initiation in cv. New Dwarf White during juvenile and competent vegetative growth related linearly to temperature, increasing between 3 and 22.8°C and then declining over the range 22.8 to 37.4°C. The first 17 leaves of celery cv. New Dwarf White had longer plastochrons of 43° Cd (>3°C) each than subsequently initiated leaves with 29° Cd for each leaf. The thermal time requirement for completion of juvenile development after radicle emergence was 731° Cd> 3°C. In cv....

Greenhouse crops: A review

Abstract: Concerns over increasing production costs and decline in crop revenues have prompted the greenhouse industry to reevaluate criteria used to select crops for greenhouse systems. In the past, crop selection was primarily based on profitability and the strategy was to manipulate the environment to tailor it to the requirements of the crop. As greenhouses are currently evolving from high energy‐consuming to cost‐efficient systems, an emerging strategy is to manipulate the crop to meet the characteristics of the greenhouse environment. To ensure efficient crop manipulation, however, an in‐depth understanding is needed of the inherent ability of crops to adapt and render economic yields under suboptimal conditions. This paper reviews key features of selected greenhouse crops, assesses the impact of changing environment on crop performance, and examines potential avenues for crop manipulation.

Identification of QTLs with additive, epistatic, and QTL × environment interaction effects for the bolting trait in Brassica rapa L.

Abstract: Bolting is an important agronomic trait in Brassica rapa crops due to its effect on yield and quality. Bolting is a complicated trait regulated by multiple genes that is highly influenced by the environment. Defining the chromosomal region(s) involved and clarifying the genetic interactions is important for improving the effectiveness of marker-assisted selection. Our objectives were to map quantitative trait loci (QTLs) controlling bolting in B. rapa and to study epistasis and QTL × environment interactions. A recombinant inbred line population (RILs, F2:6) derived from a cross between late—(08A061) and early bolting (09A001) lines was used to determine the genetic basis for three bolting indices; bolting index (BI), days to 5-cm-high elongated floral stalk (DE), and flowering time (FT) in four environments (E1–E4). Twenty-three additive QTLs were identified for BI, DE, and FT using single environment phenotypic scores. Phenotypic variation explained by each additive QTL and the total variation ranged from 5.90–33.15 %, and from 19.54–54.87 %, respectively. Eight additive QTLs and six pairs of epistatic QTLs were detected across the four environments. Phenotypic variation explained by the additive and epistatic QTLs ranged from 1.46–17.39 % and 0.70–4.73 %, respectively. Three of eight additive QTLs and zero of six pairs of epistatic QTLs showed environmental interactions. Phenotypic variation explained by each additive QTL × environment ranged from 0.88–2.15 %. Our results will contribute to an understanding of the genetic control of bolting in B. rapa, and enable breeders to determine the appropriate selection strategy with respect to bolting in breeding programs.