Abstract
Wild Helianthus species are an important genetic resource for sunflower improvement, but sometimes there are adverse interactions between the wild and cultivated sunflowers. This study reports the inheritance of reduced vigor and its restoration resulting from an interaction of perennial Helianthus cytoplasms with nuclear genes of cultivated sunflower lines. The large number of vigor restoration (V) genes identified in cultivated lines are all located at the same locus, designated V1, suggesting a common origin of these genes. Additional V genes derived from the wild perennial species H. giganteus L. and H. hirsutus Raf. are located at a different locus than V1, designated V2. A major difference between the wild annual Helianthus cytoplasms and perennial cytoplasms is the lack of the vigor-reducing cytoplasms, but surprisingly V genes were observed in wild annual H. annuus L. and H. petiolaris Nutt. which were at the same locus as V1. A common vigor-reducing cytoplasmic effect of the perennial Helianthus species and the existence of a common vigor restoration V gene in most perennial Helianthus species could be explained as a result of vigor selection during Helianthus speciation. V1 was mapped on linkage group (LG) 7 of the sunflower genome, using an F2 population derived from MOL-RV/HA 821. V1 co-segregated with an InDel marker ZVG31, with three single-nucleotide polymorphism (SNP) markers, SFW01024, SFW07230, and SFW00604, located above it on the map at a genetic distance of 0.8 cM, and another SNP marker, SFW08671, below it at a distance of 0.4 cM. The physical distance between the two closest flanking SNP markers corresponds to 0.56 and 1.37 Mb on the HA 412-HO and XRQ assemblies, respectively. The tightly linked markers will help select normal vigor progenies when using perennial Helianthus cytoplasms in a breeding program, which will also provide a basis for studying the mechanism of the cytonuclear interaction, and the speciation of annual and perennial Helianthus species.
Highlights
Crop wild relatives (CWR) are an important genetic resource for crop improvement to biotic and abiotic stresses in many crops, such as wheat, rice, maize, barley, oat, cotton, and soybean (Yumurtaci, 2015; Mammadov et al, 2018)
The research on Arabidopsis cytolines indicated that genetic variation in organelle genomes could impact three seed physiological traits including dormancy, germination performance, and longevity (Boussardon et al, 2019)
We detected a reduction of plant vigor with pale-green leaves and stunted growth in interspecific progenies involving different perennial Helianthus species, but only when using the wild perennial species as the maternal parent and cultivated sunflower as the paternal parent
Summary
Crop wild relatives (CWR) are an important genetic resource for crop improvement to biotic and abiotic stresses in many crops, such as wheat, rice, maize, barley, oat, cotton, and soybean (Yumurtaci, 2015; Mammadov et al, 2018). As with other CWR, wild Helianthus species represent a large unexploited gene pool with genetic variation for different traits, such as resistance to Sclerotinia, Phomopsis, rust, and downy mildew diseases, and parasitic broomrape (Seiler et al, 2017). They are a source of new cytoplasmic male sterility (CMS) for sunflower improvement. These amphiploids have proven to be extremely valuable in transferring resistance to Orobanche cumana Wallr. (broomrape) race F, and in the introgression of fertility restoration genes into cultivated sunflower (Jan and Fernandez-Martinez, 2002; Jan et al, 2002; Feng and Jan, 2008; Liu et al, 2013)
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