Submitted to: Eucarpia Fodder Crops and Amenity Grasses Section Symposium
Publication Type: Proceedings
Publication Acceptance Date: 12/1/2015
Publication Date: N/A
Interpretive Summary: Individual forage legume breeders currently evaluate thousands of plants a year. The breeding procedure that is proposed in this article encourages breeders to collect plant tissue samples and preserve them for possible future DNA extraction from every evaluated plant. If such a scheme is routinely used, the breeder will rapidly build up an extensive tissue sample collection that can be used to enhance the breeding program using current and, in particular, future DNA marker-based breeding technologies. This idea is particularly relevant as many DNA marker-based breeding technologies that are currently too expensive may become more affordable, and therefore be more widely used. Breeders who implement this forward-thinking breeding idea will realize cost and time savings when they do move to implement a cost-effective DNA marker based breeding technology.
Technical Abstract: Phenotyping is considered a major bottleneck in breeding programs. With new genomic technologies, high throughput genotype schemes are constantly being developed. However, every genomic technology requires phenotypic data to inform prediction models generated from the technology. Forage breeders continue to phenotype and breed various forage species often without utilizing any molecular genetic approaches in their breeding programs. The phenotyping accomplished in these traditional field breeding situations is essentially wasted in terms of contribution to current or future prediction models developed based on genomic technologies. Field breeders who are engaged in phenotyping should retain tissue samples from every selection unit proceeding through their breeding programs even if they currently are not utilizing “genomic” technology. If selection is based on family structure (e.g., halfsib selection), then parental tissue of the “family” should be retained. If selection is based on individual plants (e.g. phenotypic selection), tissue of every individual plant entering the breeding nursery should be retained. This scheme is particularly relevant to expensive phenotyped traits or long measurement time phenotyped traits (e.g., biomass yield and persistence). Traditionally, tissue for DNA extraction is stored in a frozen condition. In breeding programs, the potential exists for thousands of tissue samples, making frozen storage and tracking of tissue samples non-trivial. To alleviate such issues, tissue can be collected in inexpensive paper envelopes that have necessary identification information (with associated barcode) directly laser printed onto envelops. Small quantities of tissue are collected from selection units and placed in such paper envelopes, which are then put in a lyophilizer (i.e., freeze drier) to dehydrate the tissue while preserving DNA integrity. The tissue-containing envelopes can then be stored at ambient temperature in low humidity (< 15%) with potential tissue shelf-life reaching into decades. Required capital costs to set up this scheme are low (laser printer, benchtop lyophilizer, desiccant dehumidifier, and standard air conditioning unit). Utilizing this scheme, breeders can access their tissue sample collection to obtain DNA samples at any later date. If the scheme is used routinely, the breeder will build up an extensive collection of tissue samples over a range of germplasms and locations with phenotypic associated information and often associated remnant seed that can be utilized for genomic model development or post-phenotyping selection based on genotypic information.