Data from: Genetic and environmental determinants of unreduced gamete production in Brassica napus, Sinapis arvensis and their hybrids

Unreduced gametes, sperm or egg cells with the somatic chromosome number, are an important mechanism of polyploid formation and gene flow between heteroploid plants. The meiotic processes leading to unreduced gamete formation are well documented, but the relative influence of environmental and genetic factors on the frequency of unreduced gametes remain largely untested. Furthermore, direct estimates of unreduced gametes based on DNA content are technically challenging and hence, uncommon. Here, we use flow cytometry to measure the contribution of genetic (hybridization) and environmental (nutrient limitation, wounding) changes to unreduced male gamete production in Brassica napus, Sinapis arvensis, and two hybrid lines. Treatments were applied to greenhouse grown plants in a random factorial design, with pollen sampled at two time intervals. Overall the frequency of unreduced gametes averaged 0.59% (range 0.06%-2.17%), plus a single outlier with 27%. Backcrossed hybrids had 39% to 75% higher unreduced gamete production than parental genotypes, averaged across all treatments, although the statistical significance of these differences depended on sampling period and wounding treatment. Unreduced gamete frequencies were higher for the second sampling period than the first. There were no direct effects of wounding or nutrient regime. Our results indicate that both genetic and environmental factors can induce increased unreduced gametes, highlighting the potential importance of environmental heterogeneity and genetic composition of populations in driving polyploid evolution

不减数配子（Unreduced gametes），即携带体细胞染色体数目的精子或卵细胞，是多倍体形成以及异倍体植物间基因流动的重要机制。尽管学界已对引发不减数配子形成的减数分裂过程有了充分记载，但环境与遗传因素对不减数配子发生频率的相对影响，在很大程度上仍未得到验证。此外，基于DNA含量直接估算不减数配子的方法在技术上存在难度，因此此类研究并不多见。本研究借助流式细胞术（flow cytometry），针对甘蓝型油菜（Brassica napus）、野芥菜（Sinapis arvensis）以及两个杂交品系，探究遗传因素（杂交事件）与环境因素（营养限制、机械损伤）对雄性不减数配子产生的贡献程度。研究采用随机析因设计，对温室栽培的植株施加上述处理，并在两个时间间隔采集花粉样本。整体而言，不减数配子的发生频率平均为0.59%（范围0.06%~2.17%），另有1个异常值的发生率达27%。综合所有处理条件来看，回交杂交品系的不减数配子产生量较亲本基因型高出39%至75%，但该差异的统计学显著性取决于采样周期与机械损伤处理。第二次采样的不减数配子发生频率高于第一次采样。机械损伤与营养供应状态未对配子发生频率产生直接影响。本研究结果表明，遗传与环境因素均可诱导不减数配子产生量上升，凸显了种群环境异质性与遗传组成在推动多倍体演化过程中的潜在重要性。