Stability analysis of seven agronomic traits for soybean [(Glycine max (L.) Merr.] Tokachi nagaha and its derived cultivars using the AMMI model

The stabilities of seven agronomic traits were analyzed and the general stabilities of soybean [Glycine max (L.) Merr.] accessions were evaluated based on the additive main effects and multiplicative interactions (AMMI) model using the founder parent Tokachi nagaha and 137 of its derived cultivars as materials. The objective was to provide a theoretical basis for effectively using germplasm in soybean breeding and production. Analysis of variance (ANOVA) showed that genotype, environment, and genotype by environment interactions were significantly different for each trait. The first three interaction principal components axes (IPCA) were highly significant, accounting for 61.28–70.00% of the total variation. The stability differed for the different traits. 50 cultivars with high general stabilities were identified. The general stability of Tokachi nagaha was moderate, as the stability coefficients (D_i) of its seven traits were relatively high; this must be considered by breeders using this cultivar as a breeding parent. There were significant positive correlations between the phenotypic values and their own D_i values for number of branches per plant, number of pods per plant, number of seeds per plant, and seed weight per plant. This would lead to the expectation that the phenotypic stability would be lower when a cultivar had more branches, pods, seeds, and high per plant yields. Thus, it appears difficult to breed cultivars that simultaneously have high yields and high stability.     

Genetic analysis of resistance to spot blotch disease in wheat (Triticum aestivum L.) in Zambia

Understanding the genetics of resistance to spot blotch disease, caused by Bipolaris sorokiniana (Sacc.) Shoem, is important to design an appropriate breeding strategy to improve the trait. The objective of this study was to determine the gene action and mode of inheritance of resistance to spot blotch in wheat. Eight genotypes with varying resistance to the disease were crossed in a full diallel mating design. Parents and their progenies were evaluated for spot blotch resistance. Data were analyzed using Hayman’s diallel analysis. The results suggested the importance of additive gene effects in controlling the resistance to spot blotch in the materials under study. No epistasis, maternal, or reciprocal effects were detected. Resistance to spot blotch exhibited partial dominance. Therefore, exercising selection for resistance in the early segregating generation should be an effective approach because of the predominance of additive gene effects. The Wr/Vr graph showed that the parents 30SAWSN5 (P3) and Coucal (P4) possessed more dominant genes, which makes them particularly suitable for inclusion in breeding for resistance to spot blotch.     

Understanding farmers’ potato production practices and use of improved varieties in Chencha,Ethiopia

This study was carried out to better understand non-adoption of improved varieties of potato (Solanum tuberosum) and associated technologies by smallholder farmers in Chencha, Ethiopia. Data were collected through a survey (n = 47) and in-depth interviews (n = 20). It shows how wealth status was a factor of major importance. Most wealthy and some medium-wealthy farmers adopted improved potato varieties and many of the improved production practices; they had access to seed, associated knowledge and support, and sufficient resources that were necessary to apply the improved practices. Non-adoption was common among many medium-wealthy and most poor farmers: they lacked—next to access to the technologies and knowledge—cash, land, and labor. Results indicated the need to rethink research and intervention efforts. Next to paying attention to differences in the access to technology and the related knowledge, there is a need to consider the variation in technology needs, supporting microcredit services, and room to experiment. As a result, different combinations of improved production practices may be adopted.     

Genes for resistance to powdery mildew in European barley cultivars registered in the Czech Republic from 2011 to 2015

Barley (Hordeum vulgare) is cultivated on 49.1 million hectares worldwide with 50.2% of the area located in Europe. Powdery mildew, caused by Blumeria graminis f. sp. hordei (Bgh), occurs wherever barley is grown. Cultivar resistance plays an important role in global barley production, especially in parts of Europe where high concentrations of both spring and winter types are grown. The aim of this report was to postulate specific resistance genes in barleys from nine European countries registered in the Czech Republic from 2011 to 2015. Thirty‐five spring cultivars and 27 winter barleys were tested with 56 diverse Bgh isolates. Twenty‐five known resistance genes were postulated, and unknown genes were detected in Sandra, Saturn and Zeppelin. Unidentified specific resistance genes were also present in winter hybrids Hobbit and Wootan. Spring cultivars Arthur and Francin consisted of three and two genotypes, respectively. Resistance gene mlo was present in 26 spring cultivars, and the proportion of cultivars with this gene increased from 62.9% in 2006–2010 to 75.7% in 2011–2015. The gene Mlp1 was identified for the first time in German winter cultivar Saturn. Five spring cultivars registered in Slovakia were included in the tests. All the cultivars that were tested contained one or more specific resistance genes to powdery mildew. Adaptability of the pathogen and possibilities for breeding winter barleys are discussed.     

Frequency and fertility restoration efficiency of Rf3 and Rf4 genes in Indian rice

Identification of new parental lines is crucial for developing ecology‐specific hybrids with ideal agronomic performance. We screened a total of 570 different ecology‐specific Indian rice varieties for the presence of fertility restorer genes, Rf3 and Rf4 using tightly linked markers DRRM Rf3‐10 and RM6100, respectively. Among these varieties, 13% carried Rf3Rf3/Rf4Rf4, 31% carried rf3rf3/rf4rf4, 6% carried Rf3Rf3/rf4rf4 and remaining 50% carried Rf4Rf4/rf3rf3 allelic combinations. A mini set of 40 varieties with variable allelic combinations of fertility restorer genes were testcrossed with WA and Kalinga‐based CMS lines. All the 80 F₁s were evaluated for spikelet fertility and fertility restoration ability. Rf3Rf3/rf4rf4 genotypes mostly behaved as partial maintainers or partial restorers. In contrast, rf3rf3/Rf4Rf4 genotypes were partial or effective restorers. However, double dominant genotypes showed better fertility restoration than the genotypes containing Rf3 or Rf4 individually. Some of the genotypes showed unexpected restoration pattern implying occurrence of other fertility restorer(s) apart from Rf3 and Rf4. The perfect restorers and maintainers identified in this study can be directly used in hybrid rice breeding.     

Selection of soybean elite cultivars based on phenotypic and genomic characters related to lodging tolerance

Soybean lodging can result in serious yield reduction. Detecting the quantitative trait loci (QTL) associated with lodging tolerance for their further application in marker‐assisted selection (MAS) has the potential to enhance soybean breeding efficiency. In this study, a genome‐wide association analysis (GWAS) was performed to identify soybean accessions that could potentially be used to produce lodging‐tolerant varieties, based on the comprehensive evaluation of lodging scores (LS) obtained for the parental cultivar “Tokachi nagaha” and its 137 derived cultivars. Results showed that genotype, environment and genotype × environment interaction significantly influenced LS. Of the 31 significant SNPs identified, 22 were consistently detected in two or more environments and 27 SNPs were located in or close to agronomically important QTL mapped by linkage analysis. Best linear unbiased predictors (BLUPs) of LS tend to decrease with the elite alleles contained by accessions increasing. Some excellent accessions, with lower BLUPs and D_i (stability coefficients) values and more elite alleles, were selected. This study contributed to understand the genetic mechanism of lodging, providing genetic and phenotypic information for MAS.     

Soybean plant height QTL mapping and meta‐analysis for mining candidate genes

Plant height is closely related to seed yield of soybean. The goal of this study was to identify important loci affecting soybean plant height using meta‐analysis based on a reference physical map. Plant height related to QTLs was mapped across eight years with a RIL population by WinQTLCart v2.5. 182 QTLs related to plant height of soybean from database and our research were collected, and each QTL was projected onto the soybean physical map by software BioMercator v2.1. The confidence interval of meta‐QTL ranged from 0.09 to 5.07 Mb, and the mean phenotypic variance ranged from 4.9% to 73.0%. Furthermore, 4,259 candidate genes were located in these consensus QTLs, and 40 of them were involved in the plant growth and stem elongation and annotated as plant hormone signal transduction (pathway ID ko04075) in KEGG pathway. These results would lay a foundation for fine mapping of QTLs/genes related to plant height and marker‐assisted selection for breeding in soybean.     

Screening of Ethiopian sorghum (Sorghum bicolor) landraces for their performance under Striga hermonthica ‐infested conditions

Striga hermonthica is a major constraint to sorghum production and productivity in sub‐Saharan Africa, Ethiopia, in particular. The objectives of this study were to evaluate the performance of 49 sorghum genotypes based on their reaction to S. hermonthica and investigate the relationships among yield and Striga resistance traits, including the Striga emergence count, area under Striga number progress curve, area under Striga severity progress curve, grain yield under infested, grain yield under non‐infested conditions and relative yield loss. The genotypes differed significantly in all measured parameters under Striga‐infested and non‐infested conditions. The genotypes ‘Birhan’, ‘Gubiye’, Wolegie, Zegerie, Nechmashila I, Woftel, Tetron and Eyssa were identified as promising ones based on grain yield and Striga‐related traits. On the other hand, the genotypes Jamyo, Bobie, Gedido, Mankebar and Zengada had moderate Striga numbers with low relative yield loss as compared with susceptible checks. The most promising variety, Zegerie, Mankebar and Zengada, out yielded the standard resistant checks ‘Birhan’ and ‘Gubiye’ under Striga infestation. Ward cluster analysis grouped the 49 sorghum genotypes in to four distinct clusters under Striga‐infested conditions. All members of clusters II and III showed the highest yielding group with the lowest to moderate Striga number, while cluster IV supported the lowest yield with the highest Striga number. Significant negative correlations were observed between yield‐ and Striga‐related traits. Highly significant and strong correlations were observed among Striga resistance indices, indicating that any of the Striga resistance parameters can be used as an indicator of resistance. The wide variations in grain yield among genotypes under Striga‐infested conditions would be invaluable genetic resources for production in Striga endemic areas of Ethiopia.     

苗期耐低氮基因型苦荞的筛选及其评价指标

土壤缺氮是造成我国黄土高原冷凉地区农业低产的主要原因。为了筛选耐低氮苦荞基因型及适宜鉴定指标,采用苗期水培方式,测定9个不同基因型苦荞在不同氮水平下的农艺性状、生理特性及植株氮素利用等指标,采用隶属函数法计算各指标耐低氮指数,通过主成分分析与聚类分析评价各基因型苦荞综合耐低氮能力。结果表明,低氮胁迫下,苦荞地上部生长受抑制程度大于根系,株高、茎粗、叶面积、地上部干重、根系体积、根系表面积及根系平均直径均呈下降趋势,主根长和根冠比呈上升趋势;根系活力、根系硝酸还原酶(NR)活性及可溶性蛋白含量有所下降,而根系超氧化物歧化酶(SOD)、过氧化物酶(POD)活性、丙二醛(MDA)、可溶性糖及游离脯氨酸含量有所升高;叶片叶绿素含量、Fm和Fv/Fm降低,而Fo升高;植株全氮含量及氮积累量降低,而由于植株氮积累量降幅明显大于生物量降幅,导致氮利用效率显著升高。将25个单项指标转化为4个相互独立的综合指标(累计贡献率达87.44%),并将9个苦荞基因型划分为耐低氮型、中间型和不耐低氮型。为了预测苦荞基因型的耐低氮能力,将D值作因变量,各指标耐低氮指数作自变量进行逐步回归分析,建立最优回归方程,筛选出株高、茎粗、叶面积、根冠比、叶绿素含量、Fm、根系超氧化物歧化酶(SOD)活性及氮利用效率8项对苦荞耐低氮能力有显著影响的指标,并且9个苦荞基因型的苗期耐低氮能力预测值Y与D值显著相关(R2=0.998,P0.01),表明这8个指标可用于耐低氮苦荞基因型的快速鉴定。     

番茄绿果与橙果间果实颜色及主要色素含量的遗传研究

对番茄组合绿樱(绿果)×金珠1号(橙果)的6个世代遗传群体(P1、P2、F1、BC1、BC2和F2)进行果色性状、番茄红素含量、叶绿素含量和胡萝卜素含量等的遗传规律分析。结果表明:正反交F1的果色性状无明显差异,而色素含量存在显著差异;说明番茄果色性状受核基因控制,而色素含量遗传除受核基因控制外还可能存在胞质效应。采用多世代联合分析法的分析结果表明,番茄绿果与橙果间的果色性状符合2对加性主基因+加性-显性多基因(MX2-A-AD)遗传模型,其BC1、BC2和F2主基因遗传率分别为73.42%、78.25%和61.41%,多基因遗传率分别为22.87%、15.35%和34.94%,即果色性状遗传的主基因遗传力较强;叶绿素含量符合1对负向显性主基因+加性-显性多基因(MX1-AEND-AD)遗传模型,其BC1、BC2和F2主基因遗传率分别为0、1.73%和0.65%,多基因遗传率分别为45.47%、0和37.82%,即主基因遗传力在BC2群体中最高,多基因遗传力在BC1群体中最高;番茄红素含量与胡萝卜素含量均符合2对加性-显性-上位性主基因+加性-显性多基因(MX2-ADI-AD)遗传模型,其BC1、BC2和F2主基因遗传率分别为75.74%、1.79%、84.26%和61.53%、87.21%、81.05%,多基因遗传率分别为20.32%、74.12%、12.68%和0.68%、0、0,表明番茄红素含量和胡萝卜素含量的主基因遗传力较强。