Afolabi C G, Ojiambo P S, Ekpo E J A, Menkir A, Bandyopadhyay R
International Institute of Tropical Agriculture (IITA), P.M.B. 5320, Ibadan, Nigeria and Department of Crop Protection and Environmental Biology, University of Ibadan, Nigeria.
IITA, P.M.B. 5320, Ibadan, Nigeria.
Plant Dis. 2007 Mar;91(3):279-286. doi: 10.1094/PDIS-91-3-0279.
Fusarium ear rot and fumonisin contamination is a major problem facing maize growers worldwide, and host resistance is the most effective strategy to control the disease, but resistant genotypes have not been identified. In 2003, a total of 103 maize inbred lines were evaluated for Fusarium ear rot caused by Fusarium verticillioides in field trials in Ikenne and Ibadan, Nigeria. Disease was initiated from natural infection in the Ikenne trial and from artificial inoculation in the Ibadan trial. Ear rot severity ranged from 1.0 to 6.0 in both locations in 2003. Fifty-two inbred lines with disease severity ≤3 (i.e., ≤ 10% visible symptoms on ears) were selected and reevaluated in 2004 for ear rot resistance, incidence of discolored kernels, and fumonisin contamination in grain. At both locations, ear rot severity on the selected lines was significantly (P < 0.0020) higher in 2004 than in 2003. The effects of selected inbred lines on disease severity were highly significant at Ikenne (P = 0.0072) and Ibadan (P < 0.0001) in 2004. Inbred lines did not affect incidence of discolored kernels at both locations and across years except at Ikenne (P = 0.0002) in 2004. Similarly, significant effects of inbred lines on fumonisin concentration were observed only at Ikenne (P = 0.0201) in 2004. However, inbred lines 02C14585, 02C14593, 02C14603, 02C14606, 02C14624, and 02C14683 had consistently low disease severity across years and locations. Fumonisin concentration was significantly correlated with ear rot only at Ikenne (R = 0.42, P < 0.0001). Correlation between fumonisin concentration and incidence of discolored kernels was also significant at Ikenne (R = 0.39, P < 0.0001) and Ibadan (R = 0.35, P = 0.0007). At both locations, no significant inbred × year interaction was observed for fumonisin concentration. Five inbred lines, namely 02C14585, 02C14603, 02C14606, 02C14624, and 02C14683, consistently had the lowest fumonisin concentration in both trials. Two of these inbred lines, 02C14624 and 02C14585, had fumonisin levels <5.0 μg/g across years in trials where disease was initiated from both natural infection and artificial inoculation. These lines that had consistently low disease severity are useful for breeding programs to develop fumonisin resistant lines.
镰刀菌穗腐病和伏马毒素污染是全球玉米种植者面临的一个主要问题，而寄主抗性是控制该病最有效的策略，但尚未鉴定出抗性基因型。2003年，在尼日利亚伊凯内和伊巴丹的田间试验中，对总共103个玉米自交系进行了由轮枝镰孢菌引起的镰刀菌穗腐病的评估。伊凯内试验中的病害由自然感染引发，伊巴丹试验中的病害由人工接种引发。2003年，两个地点的穗腐病严重程度范围为1.0至6.0。挑选出52个病严重程度≤3（即穗上可见症状≤10%）的自交系，并于2004年对其进行穗腐病抗性、变色籽粒发生率和籽粒中伏马毒素污染情况的重新评估。在两个地点，2004年所选自交系的穗腐病严重程度均显著高于2003年（P < 0.0020）。2004年，所选自交系对病害严重程度的影响在伊凯内（P = 0.0072）和伊巴丹（P < 0.0001）极为显著。除2004年在伊凯内（P = 0.0002）外，自交系在两个地点及多年间均未影响变色籽粒的发生率。同样，仅在2004年的伊凯内（P = 0.0201）观察到自交系对伏马毒素浓度有显著影响。然而，自交系02C14585、02C14593、02C14603、02C14606、02C14624和02C14683在多年间和不同地点的病害严重程度一直较低。仅在伊凯内，伏马毒素浓度与穗腐病显著相关（R = 0.42，P < 0.0001）。在伊凯内（R = 0.39，P < 0.0001）和伊巴丹（R = 0.35，P = 0.0007），伏马毒素浓度与变色籽粒发生率之间也存在显著相关性。在两个地点，均未观察到伏马毒素浓度存在显著的自交系×年份互作。在两个试验中，5个自交系，即02C14585、02C14603、02C14606、02C14624和02C14683，伏马毒素浓度一直最低。其中两个自交系，02C14624和02C14585，在病害由自然感染和人工接种引发的试验中，多年间伏马毒素水平均<5.0 μg/g。这些病害严重程度一直较低的自交系对培育抗伏马毒素品系的育种计划很有用。
