Cowpea (Vigna unguiculata): Genetics,genomics and breeding

Cowpea, Vigna unguiculata (L.), is an important grain legume grown in the tropics where it constitutes a valuable source of protein in the diets of millions of people. Some abiotic and biotic stresses adversely affect its productivity. A review of the genetics, genomics and breeding of cowpea is presented in this article. Cowpea breeding programmes have studied intensively qualitative and quantitative genetics of the crop to better enhance its improvement. A number of initiatives including Tropical Legumes projects have contributed to the development of cowpea genomic resources. Recent progress in the development of consensus genetic map containing 37,372 SNPs mapped to 3,280 bins will strengthen cowpea trait discovery pipeline. Several informative markers associated with quantitative trait loci (QTL) related to desirable attributes of cowpea were generated. Cowpea genetic improvement activities aim at the development of drought tolerant, phosphorus use efficient, bacterial blight and virus resistant lines through exploiting available genetic resources as well as deployment of modern breeding tools that will enhance genetic gain when grown by sub‐Saharan Africa farmers.     

Identification of resistance to Cercospora leaf spot of cowpea

Twelve selected cowpea cultivars were screened for resistance to Cercospora leaf spot (CLS) disease caused by Pseudocercospora cruenta and Cercospora apii s. lat. under artificial epiphytotic conditions in a replicated field trial, with the objective of developing a quantitative measure of disease resistance. CLS incidence, leaf spotting score, lesion density, lesion size, proportion of nodes infected, diseased leaf area, conidia number mg⁻¹ and fascicle density were assessed in 12 cowpea genotypes at crop maturity. Proportion of nodes infected and leaf spotting score were best able to quantitatively differentiate between the levels of resistance, and allow the exploitation of quantitative resistance to the disease. Both lesion density and lesion size were important in determining the final leaf spotting score but the former was epidemiologically more important than the latter, indicated by its correlation to most of the CLS symptom measures. There was differential resistance to the P. cruenta and C. apii s. lat. among the cowpea varieties screened. Among the cowpea lines screened, resistance to P. cruenta was more common than resistance to C. apii s. lat. Nevertheless, P. cruenta was considered the more aggressive and epidemiologically more important than C. apii s. lat. on the varieties tested evidenced by the strong correlation of P. cruenta incidence with acropetal spread of CLS, intensity of leaf spotting, conidia number mg⁻¹ and fascicle density. The highly susceptible varieties namely VRB7, Los Banos Bush Sitao no.1 and CB27 were susceptible to both Cercospora pathogens. The cowpea variety VRB-10 was completely resistant to both pathogens and is a useful source of resistance in CLS breeding programmes.     

A Review on Options for Management of Cowpea Pests: Experiences From Uganda

More than 100 field pests of cowpea (Vigna unguiculata L. Walp.) can be found in most of the crop production agroecologies in Africa, but four of these – aphids (Aphis craccivora Koch), flower thrips (Megalurothrips sjostedti Trybom), the legume pod borer (Maruca vitrata Fab. Syn. Maruca testulalis Geyer) and pod sucking bugs – are commonly encountered and are of economic importance in Uganda. The diverse cowpea pest complex dictates that a single control strategy is unlikely to produce satisfactory control.Earlier field studies done in eastern and northern parts of Uganda demonstrated that close spacing (30 × 20cm) effectively reduces aphid infestation (early season pest) but seems to promote thrips, legume pod borers and pod bugs infestation. The other option for management of early season pests and nematodes is seed dressing, especially with carbofuran (Furadan 5G). Late season pests are more effectively controlled by the use of foliar sprays, the type of pesticide depending on the pest profile. Intercropping also offers remedial control, but the crop combination must consider the pest profile, cowpea/sorghum intercrop being effective against aphids and thrips, and cowpea/greengram against legume pod borers and pod sucking bugs. Selected combinations of agronomic, chemical and cultural control measures (Integrated Pest Management), especially when combined with early planting, offer better management options than the use of sole treatments. The success of these packages is highly dependent on the degree and level of farmer involvement and to what extent they are tailored to meet his/her production goals.     

小豆百粒重性状遗传体系分析

小豆百粒重是具有重要经济价值的商品品质性状。研究百粒重的遗传体系对杂交亲本的选配、杂种分离世代的选择具有实践指导意义。本文利用子粒大小不同的5个小豆亲本组配了4个杂交组合,对其衍生后代家系群体百粒重性状的遗传体系应用主基因+多基因家系世代联合分离分析方法进行了分析。结果表明,B-1(大粒)×HB801(大粒)和HB8     

EMS处理对豇豆生长发育的影响

为了使EMS诱变在豇豆育种中发挥最佳效果,获得优质的诱变材料,对豇豆品种‘天畅9号’、‘银豇王’进行了3种EMS浓度、3种处理时间的诱导处理,并对当代的种子萌发、幼苗生长、植株主要农艺性状及生化指标的变化进行研究。结果表明:EMS能导致豇豆种子的发芽力和生长速率下降,叶片变小,而种子浸出液电导率、幼苗SOD活性及可溶性蛋白质含量增加;对银豇王的叶绿素含量、一级分枝数、结荚性有增加倾向,而天畅9号表现相反。处理剂量以浓度0.3%EMS、时间3~4 h为宜。     

红小豆京农1、2号新品种选育

本地区小豆育种目标是培育早熟、高产、优质、植株直立、具有一定耐旱性的新品种。作者根据本地区夏播红小豆的育种目标,提出采用竞争性选择育种法进行小豆品种改良。经过1985～1992年7年的实践,已育成京农1号、京农2号两个新品种。大面积种植增产显著。本文还提出了基因型与适应性环境互作模型(Y=g+gE+ge+e)及竞争性选择育种法的三个先决条件。     

豇豆根瘤亚细胞组分中ASAL的分段盐析

68．5％的腺苷酸琥珀酸裂解酶(ASAL)活性和62．2％的5-氨基-4-咪唑-N-腺苷酸羧基酰胺核糖核苷酸(SAICAR)裂解酶活性分布在豇豆根瘤亚细胞的可溶性组分中。亚细胞可溶性和颗粒组分的ASAL和SAICAR裂解酶活性回收率均在50％-55％(NH4)2SO4饱和度分段盐析沉淀中出现1个峰值。但在颗粒组分提取液的60％-65％(NH4)2SO4饱和度分段盐析沉淀中,分别另有一个小的ASAL和SAICAR裂解酶活性回收率峰值出现。讨论了ASAL是1个双功能酶及其同工酶存在的可能性。     

用gfp报告基因检测土壤中Cu2+对饭豆根瘤菌生物毒性的研究

利用绿色荧光蛋白基因gfp标记研究了土壤中Cu2+胁迫对饭豆(Vigna umbellate L.)根瘤菌JMC1402G腐生存活和共生固氮能力的影响.研究结果表明在液体培养条件下,向培养基加入1μg/mL的Cu2+时,JMC1402G的生长受到轻微抑制;当Cu2+浓度达到5μg/mL和7 μg/mL时,JMC1402G的生长受到严重抑制;当Cu2+浓度达到10μg/mL时,JMC1402G已不能生长.在灭菌土壤中Cu2+添加量小于200 mg/kg时,JMC1402G数量在37 d内能保持在1.74×105cfu/g以上,当土壤中Cu2+添加量达到500 mg/kg时,在接种后第2天其数量已降至102cfu/g以下.在未灭菌土壤中,当Cu2+添加量在0～80 mg/kg范围内时,JMC1402G的数量在接种后23 d已由108cfu/g降至104～105cfu/g,随着Cu2+添加量的进一步增大,其菌数迅速下降到104 cfu/g以下.饭豆盆栽试验结果表明Cu2+添加量在0～80 mg/kg范围内对JMC1402G共生固氮的影响并不大,当土壤中Cu2+添加量达到120 mg/kg时,对JMC1402G产生较明显的生理毒性,当Cu2+添加量达到300mg/kg时,JMC1402G失去结瘤能力.     

外源硅对长豇豆锈病抗性的影响及其生理机制

研究硅对不同锈病抗性品种锈菌胁迫下过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、苯丙氨酸解氨酶(PAL)、超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量和叶绿素荧光参数及呼吸特性的影响.结果表明,外源加硅使豇豆植株叶片中SiO2含量比对照提高36.42%.硅明显提高感病品种锈菌胁迫下抗氧化酶活性,降低MDA含量,延缓植株Fv/Fm、Ф中PSⅡ和ETR的下降时间,减轻其下降程度;维持幼苗叶片较高的总呼吸活性(Vt)、替代途径能力(Valt)和替代途径实际运行活性(ρValt);未接种时外源硅对上述参数无明显影响(除POD、CAT外).硅可明显提高抗病品种接种锈菌后的POD、CAT、SOD活性,降低MDA含量,未接种时硅对上述参数无明显影响.同工酶分析表明,外源硅不能改变两品种的POD同工酶谱带.硅可显著降低感病品种的锈病病情指数,相对防效达31.7%.     

接种bradyrhizobium sp.对豇豆生物量及根瘤的影响

Vigna unguiculata(L.)Walp (cowpea)is a tropical legume of very high nutrive and economic values.A laboratory experiment.was conducted to evaluate the BNF (biological nitrogen fixation) effciency of 4 strains of Bradyrhizobium sp.(VUXYI,VUIE1,VUMDS1 and VUID1).From the results obtained these strains were classified into efficiency groups,with VUID1 being the most efficient and VUXY1 the least efficient.the effect of inoculation was tested on 2 cowpea varieties in a field experiment.Remarkable increases in nodulation biomass and crop yield were observed.An increase from 58% ti 81% in dry seed was obtained for the two varieties.A significance test revealed a signifecantly positive correlation between nodulation and biomass.