玉米黄早4雄性不育系、保持系过氧化物酶同工酶的比较研究

在玉米黄早4雄性不育系、保持系的10个组织(叶、根、茎、芽鞘、胚轴、苞叶、穗轴、花丝、雌蕊、花药)中共检测出18种正、负极向过氧化物酶,其中有7个组织不育系与保持系间过氧化物酶没有差异,只有在3个组织中(叶、茎、花药)不育系与保持系间的过氧化物酶存在差异,说明玉米黄早4雄性不育系及保持系的过氧化物酶可能由细胞核基因编码。不育系与保持系个别组织内过氧化物酶存在差异,可能是由于核内编码过氧化物酶的基因表达异常所引起,而这种表达异常,可能是与不育系中不育细胞质基因调控核基因的表达有关。     

Genetic relationship between o6 and pro-1 mutants in maize

Summary This paper reports that the opaque-6 (o6) mutation of maize, which causes seedling lethality and interferes in the endosperm with the synthesis of zeins and b-32 protein, is a proline requiring mutant functionally allelic to proline-1 (pro-1). Furthermore, immunological studies on the b-32 content of ten independently originated o6 and pro-1 alleles demonstrated that four alleles contain an apparently normal b-32 protein while the others are either devoid of it or contain trace amounts of cross-reacting proteins of lower molecular weight.     

Effect of triazinone on root growth and gravireaction

The effects of a synthetic growth promoter, 4-ethoxy-l-( p -tolyl)-S-triazine-2,6 (1H, 3H)-dione [TA], on growth and gravireaction of Zea mays L. (cv. LG 11) roots were investigated. In horizontal, intact roots, pretreatment with TA at 4 × 10⁻⁴ M inhibited the gravireaction. If the pretreated roots were rinsed with a buffer solution before incubation, the TA effect was reduced, indicating that a continuous presence of TA was necessary for its maximal activity. On the other hand, the TA pretreatment (1×10⁻⁵, 1×10⁻⁴ and 4 × 10⁻⁴ M ) promoted the elongation of these roots. The TA effect was stronger for illuminated roots than for those kept in darkness. TA also decreased the lateral curvature of half-decapitated roots maintained vertically in light. This indicates that the action of TA could be associated with some growth inhibiting substances produced or released in cap cells.     

玉米自交系间遗传距离与产量杂种优势,杂种产量的关系

以13个玉米自交系及其按双列杂交配制的78个单交种为材料,研究性状选择、亲本选择对遗传距离与产量杂种优势、杂种产量关系的影响,结果表明:(1)当性状数较少时,遗传距离与产量杂种优势、杂种产量的关系因性状的不同而异;当性状数较多时,遗传距离与产量杂种优势、杂种产量的关系为抛物线,受性状影响较小;(2)当所选亲本材料的遗传差异较大时,遗传距离与产量杂种优势的关系为抛物线;当所选亲本材料的遗传差异较小时,遗传距离与产量杂种优势的关系为直线或不相关。     

玉米花粉单倍体植株染色体上异染色质的变异

我们用Giemsa BSG C-带技术检查了玉米花药培养获得的花粉单倍体植株根尖细胞染色体上异染色质的变异,观察结果表明,有的植株所显示的C-带数目是与供体植株的相一致,有的植株所显示的C-带数目则发生了显著变化,其中有的增加,有的减少。并讨论了异染色质发生变异的可能原因。还相应地观察到间期核中染色中心的变化是与中期染色体上C-带数目的变化相一致。     

Genetic changes from introgression of highland Mexican germ plasm into a Corn Belt Dent population of maize

Summary A backcross population (NZS1) of maize (Zea mays L.) was produced by crossing a highland Mexican population with the elite Corn Belt Dent synthetic AS3, and then by backcrossing to AS3. S₁ lines, S₂ lines, and S₂ testcrosses with an elite tester were used to compare the means, correlations, genetic variances, and predicted gains from selection of NZS1 and AS3 for grain yield, grain moisture at harvest, root and stalk lodging in a cool, temperate environment in New Zealand. The S₁ and S₂ lines from NZS1 had lower mean grain yields, higher levels of root lodging and higher mean grain moistures than the S₁ and S₂ lines from AS3. Mean grain yields of testcrosses of NZS1 and AS3 were similar, but NZS1 testcrosses had higher levels of root lodging. Genotypic variances estimated from S₁ and S₂ lines were larger for grain yield and root lodging for NZS1, smaller for grain moisture, and similar for stalk lodging. Predicted gains from selection for grain yield using intrapopulation methods based on the additive-genetic variance were larger for NZS1, but predicted gains for testcross selection were similar for the two populations. Lines with high combining ability for grain yield and acceptable grain moisture in combination with the tester occurred in NZS1. Because of the higher additive-genetic variance and the occurrence of lines with high combining ability for grain yield, we concluded that populations including highland Mexican germ plasm should be valuable for recurrent selection programs in New Zealand and in other cool, temperate regions.