Quantitative genetic analysis reveals potential to breed for improved white clover growth in symbiosis with nitrogen-fixing Rhizobium bacteria

Quantitative genetic analysis reveals potential to breed for improved white clover growth in symbiosis with nitrogen-fixing Rhizobium bacteria

White clover ( Trifolium repens ) is integral to mixed pastures in New Zealand and temperate agriculture globally. It provides quality feed and a sustainable source of plant-available nitrogen (N) via N-fixation through symbiosis with soil-dwelling Rhizobium bacteria. Improvement of N-fixation in wh...

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Published in:Frontiers in plant science Vol. 13; p. 953400
Main Authors: Weith, Sean K., Jahufer, M. Z. Zulfi, Hofmann, Rainer W., Anderson, Craig B., Luo, Dongwen, Ehoche, O. Grace, Cousins, Greig, Jones, E. Eirian, Ballard, Ross A., Griffiths, Andrew G.
Format: Journal Article
Language:English
Published: Frontiers Media S.A 20-09-2022
Subjects:
genetic gain
nitrogen fixation
Plant Science
plant-microbe interactions
quantitative genetics and breeding
Rhizobium leguminosarum bv. trifolii TA1
Trifolium repens (white clover)
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Summary:White clover ( Trifolium repens ) is integral to mixed pastures in New Zealand and temperate agriculture globally. It provides quality feed and a sustainable source of plant-available nitrogen (N) via N-fixation through symbiosis with soil-dwelling Rhizobium bacteria. Improvement of N-fixation in white clover is a route to enhancing sustainability of temperate pasture production. Focussing on seedling growth critical for crop establishment and performance, a population of 120 half-sibling white clover families was assessed with either N-supplementation or N-fixation via inoculation with a commercial Rhizobium strain (TA1). Quantitative genetic analysis identified significant ( p  < 0.05) family additive genetic variance for Shoot and Root Dry Matter (DM) and Symbiotic Potential (SP), and Root to Shoot ratio. Estimated narrow-sense heritabilities for above-ground symbiotic traits were moderate (0.24–0.33), and the strong ( r  ≥ 0.97) genetic correlation between Shoot and Root DM indicated strong pleiotropy or close linkage. The moderate ( r  = 0.47) phenotypic correlation between Shoot DM under symbiosis vs. under N-supplementation suggested plant growth with mineral-N was not a strong predictor of symbiotic performance. At 5% among-family selection pressure, predicted genetic gains per selection cycle of 19 and 17% for symbiotic traits Shoot DM and Shoot SP, respectively, highlighted opportunities for improved early seedling establishment and growth under symbiosis. Single and multi-trait selection methods, including a Smith-Hazel index focussing on an ideotype of high Shoot DM and Shoot SP, showed commonality of top-ranked families among traits. This study provides a platform for proof-of-concept crosses to breed for enhanced seedling growth under Rhizobium symbiosis and is informative for other legume crops.
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Edited by: Sergio J. Ochatt, INRA UMR1347 Agroécologie, France
This article was submitted to Plant Breeding, a section of the journal Frontiers in Plant Science
Reviewed by: Muthu Venkateshwaran, University of Wisconsin–Platteville, United States; Odd Arne Rognli, Norwegian University of Life Sciences, Norway
ISSN:1664-462X
1664-462X
DOI:10.3389/fpls.2022.953400