Grain mould resistance and associated characters of sorghum genotypes

Twenty-two sorghum genotypes were evaluated for grain mould response, 13 morphological and biochemical traits thought to contribute to resistance, and 3 agronomic traits related to utilization. Measurements of grain mould (field grade score, threshed grade score, ergosterol content, and percentage germination) were strongly correlated with one another. Highly significant correlations between measures of grain mould and seed hardness, seed phenol content in acid methanol extract, and glume colour indicated that they strongly affected grain mould response. Harder grain, higher levels of seed phenols, and darker glumes contributed to grain mould resistance. Weaker and less consistent correlations between measures of grain mould and seed colour, seed flavan-4-ol content, glume phenol and flavan-4-ol contents, and glume cover indicated relatively less effect of these traits on grain mould response. Genotype means indicated that combinations of several traits are required to achieve resistance. Germplasm lines, including coloured-seeded lines IS 14375, IS 14387, IS 18144, and IS 18528, and white-seeded lines IS 21443, IS 24495 and IS 25017, showed greatest grain mould resistance. Improved lines generally had poorer grain mould resistance than these landraces. However, the best improved lines were comparable in resistance to white-seeded landraces. B58586, IS 14375 and IS 14387 are hard-seeded guinea sorghum lines that can be used as sources of grain mould resistance for West Africa. SP 33316, SP 33349 and GM 15018 are agronomically elite lines that can be used as sources of grain mould resistance for further improvement of white-seeded sorghum for South Asia and other regions. This revised version was published online in July 2006 with corrections to the Cover Date.     

水稻次生代谢物质介导红腹缢管蚜与白背飞虱的种间互作关系

【目的】探究白背飞虱Sogatella furcifera与红腹缢管蚜Rhopalosiphum rufiabdominalis种间互作机制，以及2种昆虫互作过程中水稻次生代谢物质的作用。【方法】将白背飞虱和红腹缢管蚜按不同比例混合饲养，待白背飞虱长至成虫后分组配对，分析白背飞虱总产卵量及日均产卵量；测定各处理的水稻草酸、黄酮及总酚含量，利用GC/MS仪器分析各处理水稻幼苗次生代谢物质成分的差异。【结果】“15头蚜虫+5头白背飞虱”处理的白背飞虱总产卵量仅为131.67粒，与“20头白背飞虱”处理(214.60粒)差异显著，日均产卵量也呈现相同的规律；“15头蚜虫+5头白背飞虱”处理的水稻黄酮和总酚含量分别为1.98和63.71 mg/L，均显著高于其他处理。GC/MS分析表明，“15头蚜虫+5头白背飞虱”处理的水稻中丙丁酚相对含量高达75.78%，而其余处理的水稻中不存在此种酚类物质。【结论】红腹缢管蚜可能是通过刺激水稻提高黄酮及总酚含量，进而抑制白背飞虱的生殖能力，其中丙丁酚可能在白背飞虱和红腹缢管蚜种间互作中起着关键作用。