Emendack Yves, Sanchez Jacobo, Laza Haydee
Cropping Systems Research Laboratory, United States Department of Agriculture - Agricultural Research Service (USDA-ARS), Lubbock, TX, United States.
Davis College of Agricultural Sciences and Natural Resources, Texas Tech University, Lubbock, TX, United States.
Front Plant Sci. 2025 May 8;16:1558712. doi: 10.3389/fpls.2025.1558712. eCollection 2025.
Dhurrin is a cyanogenic glucoside found in all vegetative tissues of , functioning as a herbivore repellent, antifungal agent, osmoprotectant, and nitrogen (N) storage. Dhurrin concentration is usually highest in young seedlings, where it rapidly accumulates following germination, after which its biosynthesis decreases and its turnover increases as the seedling ages. To avoid prussic acid poisoning from dhurrin catabolism in cattle grazing or foraging on sorghum, numerous research studies now focus on breeding for dhurrin-free or acyanogenic sorghum using EMS (Ethyl methanesulfonate) mutants with a non-functional dhurrin biosynthetic pathway. However, there has been limited and conflicting research investigating the role dhurrin plays as a potential nitrogen source in sorghum's early seedling growth, especially under N deficiency. It is plausible that the presence of background mutations in dhurrin-free sorghum mutants could mask or confound how the absence of dhurrin affects early seedling growth. Using a naturally occurring (non-mutant) ultra-low dhurrin genotype and known low and high dhurrin genotypes, the current research investigated the importance of dhurrin as a potential endogenous nitrogen source for early seedling growth in simulated non-marginal (N-available) and marginal (N-deficient) media. Dhurrin was implicated to be an N source for seedling growth from 8 to 13 days after planting under deficient N conditions. In N-deficient media at 13 days after planting, high-dhurrin-level genotypes accumulated more seedling fresh shoot biomass than low-dhurrin-level genotypes. Thus, while acyanogenic sorghum will be beneficial in expanding sorghum's economic value, the use of dhurrin knock-out mutants can prove problematic since the complete lack of dhurrin may affect field germination and stand establishment, particularly under N-deficient or low-N-input conditions.
蜀黍苷是一种含氰糖苷，存在于高粱的所有营养组织中，具有食草动物驱避剂、抗真菌剂、渗透保护剂和氮（N）储存的功能。蜀黍苷浓度通常在幼苗中最高，在萌发后迅速积累，之后随着幼苗生长，其生物合成减少，周转增加。为避免在放牧或觅食高粱的牛群中因蜀黍苷分解代谢产生氢氰酸中毒，目前许多研究致力于利用具有无功能蜀黍苷生物合成途径的甲基磺酸乙酯（EMS）突变体培育无蜀黍苷或不产氰的高粱品种。然而，关于蜀黍苷在高粱幼苗早期生长中作为潜在氮源所起作用的研究有限且相互矛盾，特别是在氮缺乏的情况下。无蜀黍苷高粱突变体中存在的背景突变可能会掩盖或混淆蜀黍苷缺失对幼苗早期生长的影响，这是有道理的。本研究使用一种天然存在的（非突变）超低蜀黍苷基因型以及已知的低蜀黍苷和高蜀黍苷基因型，调查了蜀黍苷作为潜在内源性氮源在模拟非边缘（氮可利用）和边缘（氮缺乏）培养基中对幼苗早期生长的重要性。研究表明，在缺氮条件下，种植后8至13天，蜀黍苷是幼苗生长的氮源。在种植后13天的缺氮培养基中，高蜀黍苷水平的基因型比低蜀黍苷水平的基因型积累了更多的幼苗地上部鲜生物量。因此，虽然不产氰高粱将有利于扩大高粱的经济价值，但使用蜀黍苷敲除突变体可能会出现问题，因为完全缺乏蜀黍苷可能会影响田间发芽和植株建立，特别是在缺氮或低氮输入条件下。
