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ABSTRACT Sugarcane (Saccharum spp. hybrids) are complex polyploid and aneuploid interspecific hybrids with 110–130 chromosomes. A traditional sugarcane breeding cycle takes 13–15 years and involves multiple years and locations testing of yield. To identify molecular markers associated with yield‐related traits, the LCP 85‐384 cultivar and its mapping population of 263 self‐progenies were planted in two randomly replicated field plots. The mapping population was genotyped with amplified fragment length polymorphism (AFLP), simple sequence repeats (SSR) and target region amplification polymorphism (TRAP) markers. Data on plant height, stalk number, stalk diameter and stalk weight were collected. A large variation was observed for each trait. A genome‐wide association study (GWAS) was conducted using mixed linear model (MLM), generalized linear model (GLM) and single marker regression (SMR) programmes of TASSEL 5 and FarmCPU of GAPIT 3. A total of 64 yield trait‐associated alleles were identified, including 11 for stalk number, 36 for stalk weight, 21 for stalk diameter and 5 for plant height. Of the 64 alleles, seven were linked to two traits and one to three traits. Genomic prediction (GP) was also performed by cross‐prediction with five models, namely, ridge regression best linear unbiased prediction (rrBLUP), Bayesian ridge regression (BRR), Bayesian A (BA), Bayesian B (BB), and Bayesian least absolute shrinkage and selection operator (BL). Prediction accuracy (r value) reached 0.40 for plant height, 0.36 for stalk number, 0.44 for stalk diameter and 0.54 for stalk weight with the standard errors from 0.009 to 0.012. Once verified, these markers will be a valuable tool to aid in the selection of yield‐related traits in sugarcane improvement programmes. [ABSTRACT FROM AUTHOR]

Sesame is an important oil crop in Ethiopia and other regions in terms of both area coverage and production. However, productivity is low due to biotic and abiotic stresses. Therefore, dissecting the genetic basis of quantitatively inherited yield‐related traits is instrumental to developing stable and high‐yielding varieties. A genome‐wide association study (GWAS) was performed with a diverse set of 300 sesame accessions tested in two environments and 2997 SNP markers. In total, 21 significant marker–trait associations (MTAs) were detected for seven yield‐related traits, including days to flower initiation (DFI), days to 50% flowering (DF), days to physiological maturity (DM), capsule length (CAPL), seeds per capsule (SPC), 1000‐seed weight (TSW) and bacterial blight (BBL). The majority of MTAs detected on LG 3, 7 and 8 were associated with traits related to physiological periods. Dissecting genetic control of flowering time and maturity has a pivotal contribution to fostering sesame breeding and developing new varieties adaptable to changing climatic conditions. Our GWAS results will assist in incorporating alleles into the elite sesame germplasm through marker‐assisted selection. [ABSTRACT FROM AUTHOR]

Average maize yield per hectare has increased significantly because of the improvement in high‐density tolerance, but little attention has been paid to the genetic mechanism of grain yield response to high planting density. Here, we used a population of 301 recombinant inbred lines (RILs) derived from the cross YE478 × 08–641 to detect quantitative trait loci (QTLs) for 16 yield‐related traits under two planting densities (57,000 and 114,000 plants per ha) across four environments. These yield‐related traits responded differently to high‐density stress. A total of 110 QTLs were observed for these traits: 33 QTLs only under low planting density, 50 QTLs under high planting density and 27 QTLs across both densities. Only two major QTLs, qCD6 and qWKEL2‐2, were identified across low‐ and high‐density treatments. Seven environmentally stable QTLs were also observed containing qED6, qWKEL3, qRN3‐3, qRN7‐2, qRN9‐2 and qRN10 across both densities, as well as qRN9‐1 under low density. In addition, 16 and eight pairs of loci with epistasis interaction (EPI) were detected under low and high planting densities, respectively. Additionally, nine and 17 loci showed QTL × environment interaction (QEI) under low‐ and high‐density conditions, respectively. These interactions are of lesser importance than the main QTL effects. We also observed 26 pleiotropic QTL clusters, and the hotspot region 3.08 concentrated nine QTLs, suggesting its great importance for maize yield. These findings suggested that multiple minor QTLs, loci with EPI and QEI, pleiotropy and the complex network of "crosstalk" among them for yield‐related traits were greatly influenced by plant density, which increases our understanding of the genetic mechanism of yield‐related traits for high‐density tolerance. [ABSTRACT FROM AUTHOR]

Heterosis is a phenomenon whereby hybrids of inbred lines produce favourable phenotypes that exceed those of their parents. Traits of interest are higher yield and stronger stress tolerance. The two-line super-hybrid rice 'Liangyoupei9' ( LYP9) shows superiority to both its elite inbred line '93-11' and 'Pei'ai64s' (' PA64s') parents and conventional hybrids. However, the genetic basis of its hybrid vigour, especially yield determination, remains elusive. In the present study, a set of 156 chromosome segment substitution lines ( CSSLs) carrying overlapping segments from ' PA64s' in a genetic background of '93-11' were constructed and planted in six environments. Three major agronomic traits, viz. panicle length ( PL), heading date ( HD) and plant height ( PH), and five yield-related traits, viz. grain weight per panicle ( GWP), number of grains per panicle ( GPP), 1000-grain weight ( TGW), seed set ( SS) and number of panicles of per plant ( PPP), were evaluated over 3 years. Quantitative trait loci ( QTL) analysis was conducted using a likelihood ratio test based on stepwise regression. Forty-six putative QTL distributed on 11 chromosomes were detected in more than one year. Remarkably, GWP of four CSSLs carrying positive yield QTL outperformed the recurrent parent '93-11' by more than 15%, in at least two environments. These results indicate that CSSLs are effective in identifying yield-associated traits, and lines harbouring such QTL will be rich in resources for future molecular breeding programmes. [ABSTRACT FROM AUTHOR]

A set of sunflower recombinant inbred lines (RILs) was used to study agronomical traits under greenhouse and field conditions each with two water treatments and three replications. The difference among RILs was significant for all the traits studied in all conditions; and water treatment × RILs interaction was also observed for most of the traits in both field and greenhouse conditions. Because of the low rate of drought stress, this part of field data are not informative. Several quantitative trait loci (QTLs) were identified for yield-related traits with the percentage of phenotypic variance explained by QTLs ( R2) ranging from 4% to 40%. Several QTLs for grain yield per plant (GYP) under four water treatments were identified on different linkage groups, among which two were specific to a single treatment ( GYPN.4.1, GYPI.7.1). Three QTLs for GYP were overlapped with several QTLs for drought-adaptative traits detected in our previous study ( Poormohammad Kiani et al. 2007b ). The whole results do highlight interesting genomic regions for marker-based breeding programmes for drought tolerance in sunflower. [ABSTRACT FROM AUTHOR]