Data from: Seed fates in crop-wild hybrid sunflowers: crop allele and maternal effects

Domestication has resulted in selection upon seed traits found in wild populations, yet crop-wild hybrids retain some aspects of both parental phenotypes. Seed fates of germination, dormancy, and mortality can influence the success of crop allele introgression in crop-wild hybrid zones, especially if crop alleles or crop-imparted seed coverings result in out-of-season germination. We performed a seed burial experiment using crop, wild, and diverse hybrid sunflower (Helianthus annuus) cross types to test how a cross type’s maternal parent and nuclear genetic composition might affect its fate under field conditions. We observed higher maladaptive fall germination in the crop- and F1- produced seeds than wild-produced seeds and, due to an interaction with percent crop alleles, fall germination was higher for cross types with more crop-like nuclear genetics. By spring, crop-produced cross types had the highest overwintering mortality, primarily due to higher fall germination. Early spring germination was identical across maternal types, but germination continued for F1-produced seeds. In conclusion, the more wild-like the maternal parent or the less proportion of the cross type’s genome contributed by the crop, the greater likelihood a seed will remain ungerminated than die. Wild-like dormancy may facilitate introgression through future recruitment from the soil seed bank.

驯化过程会对野生种群的种子性状产生选择作用，而作物-野生近缘杂交种会保留双亲表型的部分特征。种子的萌发、休眠与死亡三种命运，会影响作物等位基因在作物-野生杂交带中的渐渗（introgression）成功性，尤其当作物等位基因或作物赋予的种子种被结构导致种子在非适宜季节萌发时，该影响更为显著。本研究以栽培向日葵、野生向日葵及多种杂交型向日葵（Helianthus annuus）为材料开展种子埋藏实验，旨在探究杂交型的母本来源与核遗传组成如何影响其在田间环境下的种子命运。研究发现，栽培亲本及F₁代产生的种子出现适应不良的秋季萌发比例显著高于野生亲本产生的种子；且由于与作物等位基因占比存在互作效应，核遗传组成更偏向栽培种的杂交型种子秋季萌发率更高。至春季时，以栽培种为亲本的杂交型种子越冬死亡率最高，这主要源于其较高的秋季萌发率。不同母本类型的种子早春萌发率并无显著差异，但F₁代产生的种子仍会持续萌发。综上，母本越偏向野生近缘种，或杂交型基因组中栽培种的占比越低，种子保持休眠而非死亡的概率就越高。具备野生种式的休眠特性，或可通过土壤种子库在未来完成种群补充，从而促进等位基因渐渗过程。