玉米苗期对丝黑穗病抗性机制初探

A Preliminary Study on the Mechanism of Seedling Resistance of Maize to Head Smut

以１１个不同抗性的玉米自交系和杂交种种苗为材料对玉米丝黑穗病（Ｓｐｈａｃｅｌｏｔｈｅｃａｒｅｉｌｉａｎａ）抗性机制作了初探。结果表明：冬孢子在感病的玉米材料胚芽鞘上的萌发率（１３．２３％～１８．８１％）显著高于在抗病的玉米材料胚芽鞘上的萌发率（６．６０％～７．１０％）；感病材料幼苗中维生素Ｃ（Ｖｃ）和总糖的含量分别为１４．９１～１９．７１ｍｇ／１００ｇ鲜重和４．２３％～５．９１％，显著高于抗病材料幼苗中Ｖｃ和总糖的含量（７．１８～１０．７６ｍｇ／１００ｇ鲜重、２．５２％～３．７８％）；且二者与冬孢子在胚芽鞘上的萌发率呈显著的正相关（ｒ＝０．８４７６，０．８６１２），揭示了玉米幼苗期抗侵入的固有抗性；受玉米丝黑穗病菌侵染后，幼苗胚芽鞘内表皮在０．５３ｍｏｌ／Ｌ高渗蔗糖溶液中感病的玉米材料丧失质壁分离能力的细胞百分率高干抗病的玉米材料，高感杂交种“京黄４１７”胚芽鞘内表皮丧失质壁分离能力的细胞百分率最高（４７．４％）；抗病自交系Ｍｏ１７最低（２３％）二因此，冬孢子在玉米幼苗胚芽鞘上的萌发率，幼苗中Ｖｃ、总糖的含量，以及病菌侵入后胚芽鞘内表皮丧失质壁分离能力的细胞百分率可作为玉米早期抗丝黑穗病的鉴定指标。

In the early stage of maize growth, the mechanism of seedling resistance of maize to head smut was studied with 11 self-bred lines and hybrids with different resistance to head smut. It was showed that the germination rates of teliospores on coleoptiles of susceptible maize materials (13. 23%～18. 81 % ) were higher than on coleoptiles of resistant maize materials (6.6%～7. 10% ). The content of both Vc and total sugar in seedlings of susceptible maize materials.Results revealed significant correlation (r=0. 8467,0. 8612) between the contents of both Vc and total sugar in maize seedlings and germination rates of teliospores on the coleooptiles. It was suggested that the resistance of maize to head smut seemed to resistant against infection at the seedling of maize. After infection by Sphacelotheca reiliana, the rates of ability of separation between cell wall and cytoplasm in the inner epiderm of coleoptile losed in susceptible maize materials (47. 4% with 'Jinghuang 417', a maize susceptible hybrid) were higher than in the resistant maize materials (23% with 'Mo17', a resistant selt-bred line). As the above, the germination of teliospore on seedling cookoptile, the contents of both Vc and total sugar, and the rates of ability of separation of cell wall and cytoplasm in inner epiderm of coleoptiles after infection are recommened as the resistance indexes.