College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China.
BMC Plant Biol. 2020 Feb 11;20(1):69. doi: 10.1186/s12870-020-2278-9.
Acetolactate synthase (ALS)-inhibiting herbicides from the chemical families of sulfonylureas and imidazolinones are used worldwide. However, drift or sprayer contamination from some sulfonylurea herbicides causes a high level of male sterility in cruciferous species, especially oilseed rape (OSR). In this paper, we evaluated the gametocidal effects of 27 ALS-inhibiting herbicides that were sprayed on OSR plants at the bolting stage.
OSR anther development was very sensitive to sublethal exposure to most ALS-inhibiting herbicides. The application of 18 out of the 20 tested sulfonylureas (except ethametsulfuron and ethoxysulfuron), two imidazolinones (imazethapyr and imazamox), and one sulfonylamino-carbonyltriazolinone (flucarbazone-sodium) at suitable rates could induce male sterility. Eight of the herbicides, including chlorsulfuron (at application rates of 60-120 mg/ha), halosulfuron-methyl (300-600 mg/ha), sulfosulfuron (400-600 mg/ha), triflusulfuron-methyl (500-750 mg/ha), pyrazosulfuron-ethyl (150-225 mg/ha), nicosulfuron (200-300 mg/ha), imazethapyr (750-1125 mg/ha), and imazamox (400-800 mg/ha), could induce over 90% male sterility and over 60% relative outcrossed seed set in six cultivars with different origins. These eight chemicals could be used as new gametocides for hybrid seed production. This study also examined the possibility of external application of these gametocides on several unstable Polima cytoplasmic male sterile and thermosensitive genic male sterile lines. Although the outcrossed seed set of the treated lines was slightly reduced, the gametocide application significantly increased the seed purity of the resulting hybrid.
The finding of the gametocidal effects of most sulfonylureas and imidazolinones are of great importance for developing new functions for ALS-inhibiting herbicides. The application of gametocides will also greatly promote the safe utilization of environment-sensitive male sterility in hybrid seed production. Unexpectedly, the application of three triazolopyrimidines (florasulam, flumetsulam, and penoxsulam) and one pyrimidinylthiobenzoate (bispyribac-sodium) did not cause male sterility, although these herbicides obviously inhibited the activity of ALS and plant growth. This result suggests that inhibition of ALS activity does not always lead to male sterility in plants, and these gametocides may also inhibit other biological functions vital for microspore development.
乙酰乳酸合成酶（ALS）抑制剂除草剂包括磺酰脲类和咪唑啉酮类，在全世界范围内使用。然而，一些磺酰脲类除草剂的漂移或喷雾器污染会导致十字花科物种，尤其是油菜（OSR）产生高水平的雄性不育。在本文中，我们评估了 27 种 ALS 抑制剂除草剂在抽薹期喷施到油菜植株上的杀配子作用。
油菜花药发育对亚致死剂量的大多数 ALS 抑制剂除草剂非常敏感。20 种测试的磺酰脲类除草剂中的 18 种（ethametsulfuron 和 ethoxysulfuron 除外）、2 种咪唑啉酮类除草剂（imazethapyr 和 imazamox）和 1 种磺酰氨基羰基三唑啉酮类除草剂（flucarbazone-sodium）以适当的浓度施用均可诱导雄性不育。其中 8 种除草剂，包括氯磺隆（施用量为 60-120mg/ha）、甲磺隆-甲基（300-600mg/ha）、磺酰磺隆（400-600mg/ha）、三氟啶磺隆-甲酯（500-750mg/ha）、吡唑嘧啶-乙基（150-225mg/ha）、nicosulfuron（200-300mg/ha）、imazethapyr（750-1125mg/ha）和 imazamox（400-800mg/ha），可以在 6 个不同来源的品种中诱导超过 90%的雄性不育和超过 60%的相对异交种子结实率。这 8 种化学物质可作为生产杂交种子的新杀配子剂。本研究还考察了将这些杀配子剂外用在几种不稳定的 Polima 细胞质雄性不育和热敏基因雄性不育系上的可能性。尽管处理系的异交种子结实率略有降低，但杀配子剂的施用显著提高了杂种的种子纯度。
磺酰脲类和咪唑啉酮类除草剂的杀配子作用的发现对 ALS 抑制剂除草剂的新功能开发具有重要意义。杀配子剂的应用也将极大地促进环境敏感雄性不育在杂交种子生产中的安全利用。出乎意料的是，虽然这些除草剂明显抑制了 ALS 的活性和植物生长，但三种三唑嘧啶（氟唑磺隆、氟嘧磺隆和啶磺草胺）和一种嘧啶基硫代苯甲酸酯（双吡氟草胺）并没有导致雄性不育。这一结果表明，ALS 活性的抑制并不总是导致植物雄性不育，这些杀配子剂可能还抑制了其他对花粉发育至关重要的生物功能。
