Seedsvsfungi: an enzymatic battle in the soil seedbank

Abstract

Depleting the soil weed seedbank is an important integrated weed management strategy that has the potential to foster lasting weed control. Long-term dormancy and decay resistance of weed seeds pose a challenge to weed eradication efforts. Select soil fungi have been shown to cause significant decay of weed seeds. The physical and chemical mechanisms by which seeds in the seedbank defend themselves against pathogens have been well researched. However, very few studies have purposefully investigated the biochemical defence response of seeds. Enzyme-based biochemical seed defences have been detected in dormant and non-dormant seeds, and research supports their function in pathogen defence. This review summarizes current knowledge of the seed defence enzymes polyphenol oxidase, peroxidase, chitinase and oxalate oxidase. The fungal enzymes chitinase, protease and xylanase that function in pathogenesis of seeds in the soil seedbank are also reviewed. Progress in the development and standardization ofin situenzyme analyses fosters our understanding of actual enzyme activity present in soils, while high-throughput microplate techniques promote efficiency and enable greater scope. Application of genomic, proteomic and transcriptomic techniques to glean a deeper and more holistic understanding of the enzymatic interactions of weed seeds and soil fungi in the soil seedbank will support the development of improved integrated weed management strategies.

Influence of chaff and chaff lines on weed seed survival and seedling emergence in Australian cropping systems

“…Rainfall can potentially influence weed seed survival by changing seed dormancy levels and stimulating out-of-season fatal germination events (Cheam and Code 1995;Goggin et al 2012). Weed seed loss has been shown to occur through soil microbe-facilitated decay (Chee-Sanford 2008; Kennedy et al 1991;Kremer 1993;Pollard 2018), and higher soil moisture levels can increase this microbial activity (Davis et al 2016;Mickelson and Grey 2006). Weed seeds are also prone to predation by vertebrates and invertebrates, with crop residue levels influencing this form of seed loss (Baraibar et al 2012;Kulkarni et al 2015;Spafford Jacob et al 2006).…”

Physical Dormancy Release in Medicago truncatula Seeds Is Related to Environmental Variations

“…Phytohormones and especially gibberellins are known to play important roles in seed development and germination (reviewed in [75]), and since Medicago seeds have both physical and physiological dormancy, it is not surprising to find gibberellin 20-oxidase and two ent-kaurenoic acid oxidase genes to be associated with dormancy release (AUC 25 ) or environmental factors (BIO12), respectively. The genomic signature of M. truncatula adaptation to the climate was studied by Yoder et al [76] using essentially the same set of lines. They analyzed the relationship to BIO1, BIO3, and BIO16; thus, there is only overlap in BIO1 (annual mean temperature) with our study.…”

“…Seeds of Medicago truncatula inbred lines were selected from HapMap collection [36,76] based on accuracy of coordinates and were obtained from INRA, Montpellier, France and University of Minnesota, USA. Plants were grown in glasshouse conditions at the Department of Botany, Palacký University, Olomouc, Czechia, from March to July (2016) and from September to May (2017, 2018).…”

Main drivers of broomrape regulation. A review

“…Microbial activities also involve direct interactions with seeds that can constitute niches for some microorganisms or provide trophic resources for others, resulting in a pathogenic interaction. However, specificity has not yet been shown (Pollard 2018;Rodriguez et al 2018). Most of soil-borne pathogens are adapted to grow and survive in the bulk soil, but the place where the pathogen establishes a parasitic relationship with the plant is the rhizosphere.…”