Modern methods for genetic improvement of Trifolium pratense.

Abstract

This review focuses on trends in genetic improvement of a significant representative forage crop, Trifolium pratense (red clover) classified taxonomically into the agronomically outstanding family Fabaceae. Red clover breeding is aimed at improving traits like persistency, resistance to biotic and abiotic factors, forage yield and quality characteristics such as protein quality and stability. Isoflavone content in forage is important for cattle reproduction. Interspecific hybridization of red clover with the related wild species T. medium was used for the introgression of useful traits into red clover. The breeding strategy for the new variety Pramedi included hybrid plants with different DNA contents, repeated backcrosses with red clover, followed by family selection. New techniques of molecular genetics are becoming available to breeders for transferring key and complex traits into improved red clover varieties. Techniques such as marker-assisted selection and candidate gene identification can increase the speed and precision with which traits may be selected. Comparative sequence data analyses helped to identify genes for polyphenol oxidase enzymes and isoflavone synthase in red clover useful for DNA genotyping of individuals and breeding of improved high-quality red clover varieties.Keywords: candidate gene; genetic marker; molecular genetics; red clover; wide hybridization Throughout the history of plant breeding, breeders have endeavoured to improve crop yields and quality, always in the context of the latest knowledge and demands of users. This paper focuses on trends in genetic improvement of a significant representative forage crop, Trifolium pratense L. (red clover), by modern methods. The review summarizes current knowledge of the red clover genome and prospects for using molecular genetics to improve that genome.The genus Trifolium L. is classified taxonomically into the tribe Trifoliae of the large and agronomically outstanding family Fabaceae. It comprises approximately 240 species (Zohary & Heller 1984) of annual and perennial herbs commonly known as clovers, both wild and cultivated. Red clover is an important forage legume that is widely cultivated in most temperate regions and is grown in pastures for grazing, sown as a companion crop, and harvested for hay (Smith et al. 1985; Taylor & QueenSberry 1996). It is also used as a green manure crop because of its high nutrient content resulting partly from symbiosis with nitrogen-fixing bacteria of the genus Rhizobium.In Europe and worldwide, red clover breeding is focused on improving traits like persistency, resistance to biotic and abiotic factors, and forage yield and quality characteristics such as protein quality and stability, fermentable carbohydrate content, and cell wall digestibility. The benefits of protecting plant proteins from degradation in the rumen have been established. Polyphenol oxidase (PPO) enzymes catalyse the aerobic conversion of monophenols to o-phenols and finally to o-quinones (Macheix et al. 1991) and are present in sign...

An assessment of herbage mass, ryegrass cultivar and red clover inclusion on sward productivity, quality and morphology under a cutting protocol

“…It is important to note that while red clover had a positive effect on DM production in the current study, annual yields from red clover-based swards typically decline after 3 years from sowing (Black et al ., 2009). Improved plant persistency has however been a major objective of red clover breeding programmes in recent years (Řepková and Nedělník, 2014) and it is possible that new varieties may have greater persistency under frequent defoliation systems. A long-term study using a regular cutting protocol would therefore be beneficial.…”

Red Clover (Trifolium pratense) and Zigzag Clover (T. medium) – A Picture of Genomic Similarities and Differences

“…It is sown as a companion crop and a green manure crop to increase soil fertility. The main disadvantage of its breeding is a low persistency which is a highly complex trait that cannot be easily modified even with utilization of modern methods based on genetic improvement ( Řepková and Nedělník, 2014 ). Introduction of appropriate trait from closely related zigzag clover ( Trifolium medium L.) by means of artificial interspecific hybridization has been performed and led to a viable hybrid progeny T .…”

Transcriptome analysis reveals major transcriptional changes during regrowth after mowing of red clover (Trifolium pratense)

“…Facing today’s challenges such as an increased demand on food production in an era of global climate change, together with the aim to solve these problems in an environmental friendly and sustainable way, requires improvement of forage crops like T. pratense [ 14 , 15 ]. T. pratense breeding aims to offer genotypes with improved key agronomic traits (dry matter yield, high quality, resistance to diseases and abiotic/biotic stress, persistency), while improving its regrowth ability [ 2 , 16 ]. Unfortunately, the morphological investigations of several T. pratense populations showed a correlation of persistency with non-favorable traits, like small plant size and prostrate growth habit [ 17 ].…”