摘要
较高的受精率需要大量来自于碳氮代谢的物质和能量作为基础,而钾在植物的碳氮代谢中具有重要作用,所以钾缺乏将会显著影响碳氮代谢进而抑制生殖发育过程。为了探索钾缺乏对棉铃对位叶、叶柄韧皮部、花朵中碳氮代谢的影响,以棉花品种DP0912为材料,设置钾缺乏(0 mmol·L~(-1)K~+)和钾充足(6 mmol·L~(-1)K~+)2个处理,在人工气候室中开展2次盆栽试验。结果表明:缺钾显著降低叶片的净光合速率,但蔗糖、淀粉和氨基酸含量显著增加,因为缺钾限制了叶柄韧皮部中蔗糖和氨基酸的运输,不利于叶片中蔗糖和氨基酸的输出,最终导致缺钾雌蕊中蔗糖和氨基酸含量分别降低47.3%和51.8%,不利于淀粉和蛋白质的积累。此外,缺钾雌蕊中葡萄糖含量降低53.1%,主要因为缺钾降低了酸性转化酶和碱性转化酶活力。缺钾花朵中,较低的花粉管伸长速率和受精率伴随着较低的可溶性糖含量和ATP含量发生,且可溶性糖含量和ATP含量与花粉管伸长速率和受精率呈显著正相关,表明缺钾雌蕊中较低的物质和能量供应不能满足花粉柱头萌发和花粉管发育的需求。而且雌蕊中的蛋白质含量与花粉管伸长速率和受精率呈显著的正相关,因此缺钾雌蕊中较低的蛋白质含量也是降低花粉管伸长速率,进而导致较低受精率的原因之一。
High fertilization efficiency requires a lot of energy and substance provided by carbohydrate and protein metabolism,and potassium(K) plays an important role in carbohydrate and protein metabolism.However,it is unclear whether K deficiency limits reproductive success by disturbing carbohydrate and protein metabolism.The objectives of this study were to explore the effects of K deficiency on carbohydrate and protein metabolism in subtending leaves,phloem and pistils,and their relationship with reproductive success.A cotton cultivar DP0912 was grown in K-deficient(0 mmol·L~(-1) K~+) and K-sufficient(6 mmol·L~(-1) K~+) nutrient solution in growth chambers.Results showed that Pn was decreased by K deficiency,but sucrose,starch and free amino acid contents were markedly increased in the subtending leaves,because K deficiency limited the translocation of sucrose and amino acid in phloem.As a result,sucrose and free amino acid contents in the K-deficient pistils were reduced by 47.3%and 51.8%than K-sufficient pistils,which led to further decreases in starch and protein accumulation in the K-deficient pistils.Glucose content was also reduced by 53.1%in the K-deficient pistils than K-sufficient pistils,due to the decreased acid and alkaline invertase activities,since sucrose synthase activity was little affected.Lastly,soluble carbohydrate and ATP contents were reduced in the K-deficient pistils,similarly to pollen germination percentage,pollen tube growth rate and fertilization rate.It was concluded that the lower carbohydrate and ATP contents in the K-deficient pistils could not meet the energy requirements of pollen grain development and pollen tube growth,and protein imbalance limited pollen tube growth,which resulted in lower fertilization efficiency to limit reproductive success.
引文