小麦代换系幼苗根系对低磷胁迫的生理响应暗示的染色体效应

【目的】 以 CS (Chinese Spring，中国春) -Synthetic 6x 代换系为材料，研究小麦代换系幼苗根系对低磷胁迫的生理响应，并对相关性状进行染色体定位，为小麦耐低磷基因型的遗传改良提供理论依据。 【方法】 将母本中国春、父本 Synthetic 6x 以及代换系种子放于培养皿，于光照培养箱中培养 5 d，选择长势一致的健壮幼苗去掉胚乳，移入 Hoagland 营养液 (pH = 6.0)中培养。两叶一心时进行处理，设置正常供磷为对照 (磷浓度为2 mmol/L) 和低磷胁迫 (磷浓度为 20 μmol/L) 两个处理，四叶一心时对不同磷处理下代换系幼苗的根冠比、根系活力、酸性磷酸酶 (APase) 和核糖核酸酶 (RNase) 活性等生理指标进行测定。 【结果】 低磷胁迫下，小麦代换系苗期根冠比显著升高，APase 和 RNase 活性增强，根系活力降低；与母本中国春相比，4A、4B、6B、1D、2D 和 7D 代换系根冠比和相对根冠比显著或极显著升高，1A、2A、3A、5A、3B、7B、2D、3D、5D 和 7D 代换系的根系活力和相对根系活力显著或极显著增高，4A、1D 和 4D 代换系根系的酸性磷酸酶活性及相对磷酸酶活性均显著或极显著升高，2A、6B、4D 代换系根系的 RNase 活性和相对 RNase 活性显著或极显著增高。 【结论】 低磷胁迫下，Synthetic 6x 的 4A、4B、6B、2D 和 7D 染色体上可能存在诱导根冠比升高的基因；1A、2A、3A、5A、3B，7B、2D、3D、5D 和 7D 染色体上可能存在诱导根系活力增强的基因；4A、1D 和 4D 染色体上可能存在诱导根系酸性磷酸酶活性增强的基因；2A、6B 和 4D 染色体上可能存在诱导根系 RNase 活性增强的基因。即 Synthetic 6x 的第四染色体 (4A、4B、4D) 上可能存在调控根系相关特性的关键基因。

Chromosome control implied by the physiological responses of root in wheat substitution lines seedlings under phosphorus deficiency stress

Objectives]Studying on the physiological responses of seedling roots of wheat substitution lines to phosphorus deficiency stress and chromosomal localization of genes controlling root properties will provide theoretical support for screening cultivars tolerant to low phosphorus.[Methods]The seeds of mother line‘Chinese Spring (CS)’and father line “Synthetic 6x” as well as the substitute seeds of CS with Synthetic 6x were placed in cultural dishes for germination for 5 days. Then healthy and uniform seedlings were chosen and removed off endosperms, then cultured in Hoagland solution (pH 6.0) until the third leaf sprouting. The seedlings were grown in P2O52 mmol/L (normal control) or low P2O5stress (P2O520 μmol/L) until the fifth leaf start to sprouting. The root-shoot ratio, root activity, root Apase and RNase activity and chromosome control were observed using wheat substitution lines seedling under different phosphorus treatments.[Results]The root-shoot ratio, Apase activity and RNase activity increased, and root activity reduced under phosphorus deficiency stress. The root-shoot ratio and relative root-shoot ratio of 4A, 4B, 6B, 1D, 2D and 7D substitution lines were significantly or very significantly higher than those of the female parent Chinese Spring, root activity and relative root activity of 1A, 2A, 3A, 5A, 3B, 7B, 1D, 2D, 3D, 5D and 7D substitution lines were significantly or very significantly higher than those of Chinese Spring, Apase activity and relative APase activity of 4A, 1D, 4D were also significantly or very significantly higher than those of Chinese Spring. RNase activity and relative RNase activity of 2A, 6B, 4D were also significantly or very significantly higher than those of Chinese Spring.[Conclusions]For Synthetic 6x under phosphorus deficiency stress, there might exist genes on chromosome 4A, 4B, 6B, 1D, 2D and 7D to induce high root to shoot ratio, some genes on chromosome 1A, 2A, 3A, 5A, 3B, 7B, 1D, 2D, 3D, 5D and 7D to promote root activity, some genes on chromosome 4A, 1D and 4D in Synthetic 6x to regulate Apase activity, and some genes on chromosome 2A, 6B and 4D to regulate RNase activity. Generally, there might exist some key genes of regulating root characteristics on the forth chromosome (4A, 4B, 4D) of Synthetic 6x.