Euphytica最新文献

The assessment of genetic variability is indispensable for the development of high-yielding and nutritionally enriched soybean varieties. In this study, fifty-nine soybean genotypes (56 test entries and three standard checks) from different origins were characterized for eight qualitative and 20 quantitative traits. The experiment was laid out in a complete augmented block design for two consecutive seasons under natural rainfed conditions. Results revealed that among qualitative traits, flower colour was found to be most dynamic morphological marker trait for genotypic distribution. Mean square variances for twenty agro-morphological, seed yield and quality traits showed significant differences among tested genotypes for almost all studies traits. Non-hierarchical clustering classified entire set of germplasm into five groups, with the recognition of cluster IV for selection potential. Correlation analysis indicated that seed yield of soybean was positively associated with all yielding components, while a highly negative association was observed between seed quality traits such as protein content (%) and oil content (%). The multivariate principal component analysis (PCA) extracted five essential PCs, which explained 81.22% of the total accumulative variation. Moreover, PCA unveiled the most discriminatory traits as well as superior genotypes which participated intensely in phenotypic variability. Most diverse genotypes identified during study were Jhunghwang, K-D, 24,598, G-35, Brazil-3, 24,560, Ajmeri-1, NARC-2 and 24,608 for improved productivity and enhanced nutritional quality of soybean. The essential traits, including 100-seed weight, seed yield plant⁻¹, protein content and oil content depicted influential effects in identifying these desired genotypes. Conclusively, the hybridization of divergent parents in cross-breeding programs may have successful chances to get transgressive segregants with higher seed yield potential along with improved nutritional quality for developing new soybean varieties.

The presence of epistasis in complex traits can be significant and affect the selection of segregating populations undesirably. The purpose of this study was to determine the epistatic genetic components that influence root and shoot traits of common bean and identify their effect on the performance of segregating populations. The field experiment consisted of 49 treatments (backcross progenies, parents and segregating populations in the F₂ and F₃ generations). The cross P₁-BAF53 (Andean) × P₂-IPR 88 Uirapuru (Mesoamerican) as reference. Six traits were taken into consideration: root distribution (%), first pod length (cm), number of grains (plot), plant height (cm), reproductive cycle (days) and number of basal branches (plot). For root distribution, first pod length and number of grains, the additive and additive × additive components were significant. On the contrary, for plant height, reproductive cycle and number of basal branches, no interaction component was observed. These results can be explained by the magnitude of variance determined for these traits. The additive × additive epistasis had a negative influence on the mean performance of segregating progenies. Contrariwise, transgressive segregation effects on plant height were observed as a function of genetic dominance deviation. Thus, additive × additive epistasis can hamper the success of a breeding program, for being associated with low-variability traits. This fact may be related with the number of crosses and/or the choice of genetically more distant parents for the program, and possibly with the presence of linked genes.

Abstract

Cross-incompatibility is the major challenge in inter-sectional distant hybridization between tree peonies (Paeonia sect. Moutan) and herbaceous peonies (Paeonia sect. Paeonia). Most of the intersectional cross combinations rarely produce hybrid progenies or even seeds. However, a combination with Paeonia × lemoinei Rehd. (P. delavayi × P. suffruticosa, tree type) as the pollen parent and P. lactiflora (herbaceous) as the seed parent resulted in many progenies. This research focuses on cytogenetics of two highly compatible intersectional combinations, P. lactiflora ‘Martha W.’ × P. × lemoinei ‘Golden Era’ (‘MW’ × ‘GE’) and P. lactiflora ‘Fen Yun Fei He’ × P. × lemoinei ‘L’Esperance’ (‘FYFH’ × ‘LE’). Karyotype analysis combined with genomic in situ hybridization (GISH) showed that the seed parents, ‘MW’ and ‘FYFH’, are both diploids (2n = 2x = 10, CC), while the pollen parents, ‘GE’ and ‘LE’, are tetraploid (2n = 4x = 20, AABB) and diploid (2n = 2x = 10, AB) respectively. Four progenies from ‘MW’ × ‘GE’, and another four progenies from ‘FYFH’ × ‘LE’, are all triploids (2n = 3x = 15, ABC). P. × lemoinei contributes two sets of chromosomes (AB) showing distinct signals in all tested triploids. The essential of a successful intersectional hybridization is to obtain 2x gametes from tree peony. P. × lemoinei has better compatibility in intersectional hybridization than other tree peony species, probably because of its higher frequency of 2x gamete (unreduced in diploid, or reduced in tetraploid) generation. Tetraploid tree peonies, such as ‘GE’, might produce abundant 2x gametes through normal meiosis, which is the possible reason for their better fertility and superior intersectional compatibility than diploid tree peonies. The mechanism of compatibility in intersectional hybridization is supposed to be a rebalance between the distant divergent parents, tree peonies and herbaceous peonies, triggered by ploidy increase of gametes from tree peonies. The discovery of tetraploid tree peony also provides valuable materials to study the mechanism of polyploidization in sect. Moutan, and to promote the distant hybridization breeding in Paeonia.

Inflorescence structure affects final grain yield (GY) in wheat (Triticum aestivum L.). Recent breeding efforts have focused on improving grain number per spike, which is positively correlated with GY. Grain Number Increase 1 (GNI-A1) encodes a homeodomain leucine zipper class I (HD-Zip I) transcription factor that controls the number of grains per spike and GY. However, how this increase in grain number affects grain quality, especially grain protein content (GPC) in wheat, remains elusive. Here we investigated within-spikelet variation in GPC using GNI-A1 near-isogenic lines. Yield trials in two seasons and at two sites demonstrated that lines harboring a reduced-function allele, GNI-A1 (105Y), consistently showed improved GY due to a 27% increase in grain number per spike, along with a 1.7% reduction in GPC compared with lines containing a functional allele, GNI-A1 (105N). We confirmed the positive correlation between GY and grain number and the negative correlation between GY and GPC, but we observed no correlation between GY and thousand-grain weight. The increased grain number conferred by the 105Y allele was due to better floret fertility around the central part of the spike and whole florets. In-depth phenotypic analysis using dissected grain samples revealed that GPC was nearly uniform among spikelets and florets. These results suggest that in plants carrying a mutation in GNI-A1, the increase in the total number of grains is accompanied by a reduction in GPC.

Abstract

Sheath blight is an emerging disease of rice that appears in rice production areas worldwide. A total of 294 O. nivara accessions along with susceptible check PR114, the cultivated rice, were screened against sheath blight under field conditions for three consecutive years. Based on screening, 15 accessions were identified that showed moderate resistance reaction to sheath blight across the years. However, none of the accession showed highly resistant reaction. Sheath blight resistance was found to be quantitative controlled based on near normal distribution of lesion length. These 15 accessions further showed same level of resistance in detached tiller culture method and are proposed as the candidate donors for resistance to sheath blight, to be used in rice breeding programme. Further Multi locus-GWAS implemented using the 3VmrMLM model in 294 O. nivara accessions using 22,261 SNPs identified 11 marker-trait associations (MTAs) on 8 different chromosomes with the LOD score ranging from 3.34 to 20.58, while 10 out of 11 significant showed significant statistical difference based on Kruskal–Wallis test. Based on the LD decay in the panel, an interval of ± 300 kb of each significant MTA was investigated to identify candidate genes governing resistance to sheath blight. Among 11 QTL regions, a total of 19 candidate genes were found to be differentially expressed in response to the sheath blight pathogen based on in-depth in silico analysis, including those encoding lignin biosynthesis proteins, calcineurin B, thaumatin proteins, protein kinase domains, NBS-LRR domains, and cytochrome P450 oxidoreductases. The study highlighted 15 sheath blight resistant donors along with 10 QTL regions and 19 candidate genes that will provide a platform for understanding genetic basis of sheath blight resistance in rice.

Rice eating and cooking quality (ECQ) is one of the most important qualities and it has attracted more and more interests of consumers and breeders. SSIIa and Wx are the major genes affecting rice ECQ, and several alleles of SSIIa and Wx have been identified. In this study, the effects of different allele combinations of SSIIa and Wx on rice ECQ were explored by analyzing amylose content (AC), gelatinization temperature (GT), and Rapid Viscosity Analyzer (RVA) profile properties of one natural population which is composed of 30 glutinous rice varieties and 342 non-glutinous varieties. Nine allele combinations of SSIIa and Wx were identified in all the non-glutinous varieties. The allele combination of SSIIa^c/Wx^b harbored higher BDV, lower SBV, intermediate AC, and higher GT, which means better taste quality but more cooking time. For non-glutinous rice, stepwise regression analysis showed that RVA profile properties are mainly controlled by polymorphic loci of Wx-Int1(G/T) and Wx-EX10(C/T); AC, PV, BDV, and SBV are mainly controlled by Wx-Int1(G/T); HPV, CPV, and CSV are mainly controlled by Wx-EX10(C/T); GT is mainly controlled by SSIIa-EX8(GC/TT). Regression equation models also confirmed that SSIIa^c/Wx^b had better ECQ compared to other allele combinations, indicating its potential to improve rice quality. Our results may provide useful clues for elite alleles of SSIIa and Wx for introgression to other rice varieties to improve rice ECQ.

Pearl millet (Pennisetum glaucum [L.] R. Br., 2n = 2x = 14) is a nutrient-dense and climate-resilient crop widely cultivated in the dry regions of Africa and Asia. In Burkina Faso, the actual mean yield of the crop is < 1 ton/ha compared with a potential yield of 3 tons/ha. Several constraints, including cultivar susceptibility to the noxious weed Striga hermonthica (Del.) Bentham (Sh) and severe and recurrent drought stress limit the potential productivity of the crop. Therefore, this study aimed to determine the combining ability effects and degree of heterosis for agronomic traits and resistance to Sh among complementary pearl millet genotypes to select promising parental lines and hybrids to develop and deploy farmer-preferred varieties. The narrow-and broad-sense heritability were relatively higher for Striga-resistance (≥ 70%) and low (≤ 23%) for grain yield. The general combining ability and specific combining ability ratios were less than unity for agronomic traits and Striga reaction indicating the predominance of non-additive gene action conditioning the assessed traits. The new experimental hybrids such as IP-11358 × ICMB177111, IP-11358 × IKMB18002, IP-10579 × ICMB177002 and IP-9242 × ICMB177002 are recommended for multi-environment evaluation and production in Sh-infested pearl millet cultivation agro-ecologies in Burkina Faso or similar agro-ecologies.

Rice production is severely threatened by frequent outbreaks of Brown planthopper (BPH), Nilaparvata lugens (Stảl.) biotypes globally. On this account, host-plant resistance serves as an important strategy to reduce the damage caused by BPH. The wild species of rice Oryza nivara accession IRGC 93198 showed consistent resistance reaction against BPH biotype 4 for 5 consecutive years of screening under the greenhouse conditions. The mapping of the BPH resistance gene from Oryza nivara accession IRGC 93198 was conducted using BC2F2 and BC2F3 progenies. Out of 239 BC2F2 plants, 65 plants were resistant (1-3 score), and 174 plants (5, 7, and 9 score) were susceptible, thus fitting the segregation ratio of 3:1 (Susceptible: Resistant). The BC2F3 progenies segregated in 1:2:1 confirming that the resistance from O. nivara is governed by a single recessive gene. Bulked segregant analysis (BSA) identified genomic region on the short arm of chromosome 4 to be associated with BPH resistance. Molecular mapping performed on BC2F2 population identified a QTL on chromosome 4 within the marker interval RM16285 and RM6314 explaining phenotypic variance of 27% at LOD 22.34. The linked marker RM6659 was found efficient in demarcating the susceptible from resistant lines when applied on the panel of rice cultivars, hence can be used for marker assisted selection in crop breeding. The previously identified BPH-resistant genes located on chromosome 4 were found susceptible to the BPH biotype 4 screening test. This specifies bph46 to be a novel gene that can be deployed as a valuable donor in BPH resistance breeding programs.

Bacterial leaf blight, sometimes known as BLB, is one of the most damaging diseases that may jeopardize the world’s supply of rice. It is caused by the bacterium Xanthomonas oryzae pv. oryzae (Xoo). It has caused sharp decline in production in regions of the globe that produce rice. More than 40 previously characterized resistance (R) genes enable host tolerance for diverse Xoo strains. In this study, three BLB resistant genes, including xa5, xa13, and Xa21, which have been crucial in disease prevention in Bangladesh, were introgressed into populations. These populations were created by crossing IRRI 154, a popular rice variety with a modern genetic background, with IRBB66 (resistant to BLB). Fifteen virulent bacterial isolates were used for BLB infection, and promising recombinants from the F₅ and BC₂F₄ generations were found to be resistant. Using marker assisted selection (MAS) with gene-specific primers on generations F₅ and BC₂F₄, we were able to find that 60 recombinant introgressed lines (RILs) had a pyramiding of BLB resistance genes. In terms of agronomic performance, the RILs outperformed both their donor and recipient parents, demonstrating that the RILs had pyramided three resistance genes, therefore conferring broad-spectrum BLB resistance. The produced BLB-resistant RILs offer substantial future development potential, either as cultivable crops or as BLB resistance donor material for use in boosting the yields of other rice lines.

Kale is one of the main leafy vegetables grown in Brazil. However, genetic breeding programs for the development of superior cultivars are scarce. Thus, the objective of this study was to select promising genotypes and to obtain strategic information for the genetic improvement of kale from plant biometrics. The study was conducted in two stages in the horticulture sector of Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM) during 2018 and 2019. The university is located in the municipality of Diamantina, state of Minas Gerais, Brazil. The seeds used were obtained from 25 pre-selected half-sib progenies. In 2018, these progenies were recombined, selecting the seeds from plants with superior agronomic performance. Subsequently, in the year 2019, the seeds harvested in the first stage were sown, and the agronomic evaluation of the resulting plants was conducted. The experimental design was randomized blocks with four replicates and six plants per plot. At this stage, agronomic biometrics of the plants were conducted, identifying those with higher productivity and leaf quality. The genetic parameters were estimated, and the genetic gains with selection were predicted. The highest individual heritability in the narrow sense (h²_a) was observed for plant height, followed by the mean mass per leaf. The yield of leaves showed gains of 11.80, 10.39, and 7.68% at selection intensities of 10, 15, and 30%, respectively, indicating the possibility of genetic progress with the selection of superior genotypes. The individual selection approach proved effective in improving the population, however, indirect selection for increased leaf number resulted in a reduction in leaf size.