Modulating seed size in oilseed rape
Lead Research Organisation:
Rothamsted Research
Department Name: Plant Biology & Crop Science
Abstract
Seeds of oil crops provide an integrated production platform and refinery for high value fatty acids and protein meal. Brassica oilseed rape (OSR) is the primary source of vegetable oil in N.Europe, with huge potential to maximise output and quality for human and livestock nutrition, diversification of novel food and non-food products including biorenewables and first generation biofuels. An important and profitable part of the UK arable rotation, OSR is a recent crop poorly optimised for yield (UK average ~3.3 t/ha) with low harvest index (harvested biomass/total plant biomass) only ~65% of that achievable for wheat. Seed size plays a key role in the yield, quality and profitability of OSR, with ancillary effects on the early stages of crop establishment through its contribution to seedling vigour. Domestication of many crops has been accompanied by an increase in the relative size of the harvested organ, but this is not the case for the seeds of rape since it became adopted as the major oil crop in temperate regions in the past 30 years. However, there appears to be no theoretical developmental limit to making major advances to increase seed size, which should have benefits in terms of surface:volume ratio, processibility and crop establishment. The weedy thale cress species Arabidopsis thaliana has been used by the global plant research community over the past 20 years as a model organism, from which much of our current deep knowledge of the inner workings of plant growth and development has arisen. The complete DNA sequence of the Arabidopsis genome established in 2000 has enabled rapid advances to be made in understanding the role and function of individual genes in plant development. Brassicas are in the same plant family and the closest crop species, so we are able rapidly to make use of much of this fundamental information to benefit a major UK crop. Recent world-leading research at the University of Bath using Arabidopsis has established that there are two major developmental mechanisms by which seed size can be manipulated in this species. These involve firstly the role of endosperm size. Endosperm is the plant equivalent of the placenta / it obtains food from the mother and passes this to the growing embryo. Extending the growing period of the endosperm using various genetic modifications produces a larger endosperm that is better able to obtain food from the mother. The result is a larger embryo. Secondly, increasing the number of cells within the integument layers greatly increases final seed weight. The integuments form a vessel or bag within which the endosperm and embryo develop, rather like the womb of mammals. Our experiments suggest that the embryo and endosperm grow to fill the available space. Providing a larger space by increasing the size of the integuments, again using genetic modifications to development, results in a larger endosperm and embryo, and ultimately a heavier seed. We expect much of the information gained from studying Arabidopsis to be relevant to Brassica crop seeds. However, we need to check that similar mechanisms operate, since Brassica seed can be up to 400 times larger than Arabidopsis seed. In this project we will combine analytical approaches refined in Arabidopsis to study the relative development of seed size in Brassica. We will assign known variation in Brassica seed size to specific developmental mechanisms and will make use of some unique experimental resources to test hypotheses that similar mechanisms operate in the larger Brassica seeds. We will also determine whether the location of genes identified in Arabidopsis as contributing to modulation of seed size are likely to be located at predictable positions on Brassica chromosomes. The information we obtain should greatly assist plant breeders and biologists in developing appropriate screening methods for selecting material from the Brassica genepool with which to modulate seed size in a predictable manner.
Technical Summary
Seed growth in the Brassicaceae is controlled and co-ordinated by three main components: endosperm, seed integument and embryo. Currently we know of 2 mechanisms that increase seed size in the reference species Arabidopsis, 1) increased endosperm proliferation during early seed development and 2) increased growth of seed integuments. In order to establish the specific mechanisms that account for variation in seed size in Brassica, we will identify and select a small number of plant lines that represent extremes in the ranges of seed size in our reference mapping and diversity set Brassica populations. Seed from these lines will be subjected to detailed developmental morphological analyses. This will provide our first indicators to the mechanisms existing in Brassica. We have recently verified that the phenomenon of early endosperm proliferation due to paternal excess occurs in Brassica similar to the observations in Arabidopsis. By carrying out reciprocal interploidy crosses (2x X 4x), we will characterise endosperm-led modulation of seed size. Using monosomic addition lines that provide a full set of B. rapa chromosomes and one haploid member B. oleracea chromosomes for each of the 9 C genome chromosomes, we have recently identified a line that produces significantly larger seed. The data from these studies, together with a comparative genomics approach will help attribute QTL for seed size in Brassica to specific candidates and mechanisms that are being characterised in Arabidopsis. This approach will be used primarily to confirm/refute the association of QTL known to have an effect on seed size with specific genes. In parallel, we will introduce a limited number of candidate genes, identified from Arabidopsis, into Brassica plants under selected endosperm specific promoters. The seeds from the transgenic plants will be analysed for increases in seed size and the mechanisms that confer this allowing us to identify genes/loci in Brassica that modulte seed size.
Publications
Amoah S
(2012)
A hypomethylated population of Brassica rapa for forward and reverse epi-genetics.
in BMC plant biology
Geleta M
(2012)
Assigning Brassica microsatellite markers to the nine C-genome chromosomes using Brassica rapa var. trilocularis-B. oleracea var. alboglabra monosomic alien addition lines.
in TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik
Heneen W
(2012)
Seed colour loci, homoeology and linkage groups of the C genome chromosomes revealed in Brassica rapa-B. oleracea monosomic alien addition lines
in Annals of Botany
King GJ
(2010)
Exploring and exploiting epigenetic variation in crops.
in Genome
Lochlainn SÓ
(2011)
High Resolution Melt (HRM) analysis is an efficient tool to genotype EMS mutants in complex crop genomes.
in Plant methods
Stoute AI
(2012)
Parental genome imbalance in Brassica oleracea causes asymmetric triploid block.
in The Plant journal : for cell and molecular biology
Wang J
(2011)
Universal endogenous gene controls for bisulphite conversion in analysis of plant DNA methylation.
in Plant methods
Description | Brassica oilseed rape (OSR) is the primary source of vegetable oil in N. Europe, with huge potential to maximise output and quality for human and livestock nutrition, diversification of novel food and non-food products. An important and profitable part of the UK arable rotation, OSR is a recent crop poorly optimised for yield (UK average ~3.3 t/ha) with low harvest index (harvested biomass/total plant biomass) only ~65% of that achievable for wheat. Seed size plays a key role in the yield, quality and profitability of OSR, with ancillary effects on the early stages of crop establishment through its contribution to seedling vigour. Domestication of many crops has been accompanied by an increase in the relative size of the harvested organ, but this is not the case for the seeds of rape since it became adopted as the major oil crop in temperate regions in the past 30 years.The weedy thale cress species Arabidopsis thaliana has been used by the plant research community over the past 20 years as a model organism, from which much of our current knowledge of the inner workings of plant growth and development has arisen. Brassicas are in the same plant family and the closest crop species, so we are able rapidly to make use of much of this fundamental information to benefit a major UK crop. Endosperm is the plant equivalent of the placenta, it obtains food from the mother and passes this to the growing embryo within the seed. Extending the growing period of the endosperm using various genetic modifications produces a larger endosperm that is better able to obtain food from the mother. The result is a larger embryo and hence seed. In this study we determined whether a similar increase in endosperm growth would result in a change in seed size. We found that indeed, prolonging the phase of endosperm growth resulted in larger seed. We further investigated endosperm development in leafy brassicas and found that they demonstrated a strong parent-oforigin effect on seed development. If we increased the maternal factors controlling endosperm growth, we obtained viable seed but if the paternal factors were increased, it lead to a reproductive barrier termed 'triploid block' which was lethal. This phenomenon is found commonly in polyploids, and many crop species are polyploids. We also investigated the expression of genes during this lethal block and revealed the conservation of some mechanisms controlling endosperm behaviour compared to the model, Arabidopsis. Interestingly, we also found differences that may explain the failure of the paternal excess seed. Using a unique genetic resource, we also determined that 4 chromosomes contributed in particular to seed size in Brassica. A further study of the genes located on these chromosomes compared to known seed size regulatory genes may help to identify hitherto unidentified regulators of seed size in Brassica. The information we obtain should greatly assist plant breeders and biologists in developing appropriate screening methods for selecting material from the Brassica genepool with which to modulate seed size in a predictable manner. |
Exploitation Route | The information we obtain should greatly assist plant breeders and biologists in developing appropriate screening methods for selecting material from the Brassica genepool with which to modulate seed size in a predictable manner |
Sectors | Agriculture, Food and Drink |
Description | BBSRC sLoLa Brassica Rapeseed And Vegetable Optimisation |
Amount | £3,514,227 (GBP) |
Funding ID | BB/P003095/1 |
Organisation | Biotechnology and Biological Sciences Research Council (BBSRC) |
Sector | Public |
Country | United Kingdom |
Start | 01/2017 |
Description | GCRF Foundation Awards for Global Agriculture and Food Systems Research - 'Genetic improvement of rice seed vigour for dry direct-seeded conditions' |
Amount | £650,000 (GBP) |
Funding ID | BB/P023428/1 |
Organisation | Biotechnology and Biological Sciences Research Council (BBSRC) |
Sector | Public |
Country | United Kingdom |
Start | 05/2017 |
End | 04/2018 |
Description | Global Challenges Research Fund - Impact Acceleration Award Extension 2017 - 'Development and validation of new open-source phenotyping platforms for analysis of rice seedling vigour' |
Amount | £5,740 (GBP) |
Organisation | Biotechnology and Biological Sciences Research Council (BBSRC) |
Sector | Public |
Country | United Kingdom |
Start | 12/2017 |
End | 02/2018 |
Title | Screening TILLING lines using HRM |
Description | Using HRM genotyping on TILLING derived mutants, it is possible to generate an allelic series of mutations within multiple target genes rapidly. Lines suitable for phenotypic analysis can be isolated approximately 8-9 months (3 generations) from receiving M3 seed of Brassica rapa from the RevGenUK TILLING service. |
Type Of Material | Technology assay or reagent |
Year Produced | 2010 |
Provided To Others? | Yes |
Impact | Lochlainn SO, Amoah S, Graham NS, Alamer K, Rios JJ, Kurup S, Stoute A, Hammond JP, Ostergaard L, King GJ, White PJ & Broadley MR (2011) High Resolution Melt (HRM) analysis is an efficient tool to genotype EMS mutants in complex crop genomes. Plant Methods, 7: 43. 30/15/10 |
Title | Brassica small RNA from seeds |
Description | Generation of small RNA raw data from developing seed of Brassica rapa at two distinct stages of seed development. |
Type Of Material | Database/Collection of data |
Provided To Others? | No |
Impact | This small RNA data is the first that allows comparison of two distinct developmental time-points during seed maturation. |
Title | Macro for automatic tracing of seed/ovule size |
Description | A Image J macro was created will allows for automatic analyses of image data to extract seed/ovule size data. |
Type Of Material | Data analysis technique |
Year Produced | 2020 |
Provided To Others? | No |
Impact | Shared with collaborators. |
Title | Transcriptome dataset |
Description | We have generated a Brassica tissue specific transcriptome data set across 5 genotypes, 18 distinct tissues and several developmental stage. |
Type Of Material | Data analysis technique |
Year Produced | 2020 |
Provided To Others? | No |
Impact | Will allow the identification of key regulators for yield traits. Will be available once published. |
Title | seed mRNA data |
Description | Generation of mRNA transcript data from developing seed of Brassica rapa at two distinct stages of seed development. |
Type Of Material | Database/Collection of data |
Provided To Others? | No |
Impact | Transcript data helped with identifying underlying mechanims that regulate seed size in brassica. |
Description | targeted knockdowns in crops |
Organisation | National Institute of Agronomy and Botany (NIAB) |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | The NIAB crop transformation facility had an open call for transformations in crops (BBSRC funding to provide this capability to the research community free of charge). We utilised information regarding to seed size generated in our group to apply to the call to generate a knock-down in a locus of interest in rice in an attempt to see if the gene function translates from dicots species to monocot species. |
Collaborator Contribution | The partner NIAB has provided transformation and initial screening of rice knockdown lines. |
Impact | We have received RNAi rice lines which will be screened and assessed. |
Start Year | 2019 |
Description | "Seeds, shoots and leaves crop science for the next generation" |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | Yes |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | Presentation to the public at an Open meeting at Rothamsted Research as part of the 'Fascination of Plants' day. Presentation The public who attended the meeting were extremely interactive and asked for more information regarding the research. |
Year(s) Of Engagement Activity | 2012 |
URL | http://www.rothamsted.ac.uk/information-public/public-events-archive |
Description | BBSRC Darwin Connection Open Meeting |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | Yes |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | There was a huge interested from teh audience regarding the talk, presentation. The audience commented on how they weren;t aware of the level of diversity present in species. They also mentioned how next time they were buying vegetables, food, they would be more aware and also try and find out more about what they eat and where the food comes from. Increased level of public interest in knowing about our research and incraesed support for it. |
Year(s) Of Engagement Activity | 2009 |
Description | Diversity of Brassica crops |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | Yes |
Geographic Reach | Regional |
Primary Audience | Public/other audiences |
Results and Impact | Science exhibition stand with posters, handouts, brassica plants and vegetables to explain Brassica genomes, brassica plants grown in the UK, genetic diversity. Posters, laminated teaching resources. The public feedback was extremely encouraging- the public realised that information about where their ffod comes from is inportant, they were encouraged to be more inquisitive about food, crops and diversity in crops. |
Year(s) Of Engagement Activity | 2010 |
Description | Open Weekend |
Form Of Engagement Activity | Participation in an open day or visit at my research institution |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | Amazing weekend with thousands of visitors to the stand specifically on brassicas but also the whole Institute. There was a large amount of interaction with the public in terms of dissemination of information, the public curiosity about our research and even more importantly how we were so passionate and enthusiatic about what we do. The confidence of the public in our research is increased. They feel we are undertaking a valuable service. They were also extremely interested in the health benefits of oilseed rape. They were also accpeting of GM research and the possibility that GM crops may be part of the future. |
Year(s) Of Engagement Activity | 2010 |
Description | Presentation at UK-BRC 2020 |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | New findings presented at the Annual UK-BRC conference held virtually in Nov 2020. |
Year(s) Of Engagement Activity | 2020 |
Description | Presentation to potential new collaborators at CIRAD |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Discussions with Dr Christophe PERIN at CIRAD, Montepelier (attended by Pete, Smita and Gui). Presentation from both sides regarding research, possible collaborations, new tools for analysing transcriptome data |
Year(s) Of Engagement Activity | 2021 |
Description | The Challney-Rothamsted Science at work project |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Schools |
Results and Impact | "The Challney-Rothamsted Science at work project" is funded by STEM to address particular groups of school students, normally under-represented in science and technology. We target local schools, in this case we had school children with a large representation of certain ethnic groups that are underrepresented in science and engineering. The project involved meeting students, explaining current research and describing my career as a female scientist. The workshop generated high interest from the students. Interestingly, students wanted to know about career options in terms of salary and economic benefits inplying these are important factors in decision making. The need for strong female role models was also apparent. Feedback from the teacher in the school indicates a larger awareness of science as a career choice. I think actually seeing a research organisation and interacting with scientists made a big differnce to the students. |
Year(s) Of Engagement Activity | 2008 |