Genomic versus phenotypic selection to improve corn borer resistance and grain yield in maize.

Introduction: The study of yield and resistance/tolerance to pest are related traits fundamental for maize breeding programs. Genomic selection (GS), which uses all marker information to calculate genomic breeding values, is presented as an emerging alternative to phenotypic and marker-assisted selections for improving complex traits controlled by many genes with small effects. Therefore, although phenotypic selection (PS) has been effective for increasing resistance and yield under high infestation with maize stem borers, higher genetic gains are expected to be obtained through GS based on the complex architecture of both traits.

Domestication reshaped the genetic basis of inbreeding depression in a maize landrace compared to its wild relative, teosinte.

Inbreeding depression is the reduction in fitness and vigor resulting from mating of close relatives observed in many plant and animal species. The extent to which the genetic load of mutations contributing to inbreeding depression is due to large-effect mutations versus variants with very small individual effects is unknown and may be affected by population history. We compared the effects of outcrossing and self-fertilization on 18 traits in a landrace population of maize, which underwent a population bottleneck during domestication, and a neighboring population of its wild relative teosinte.

A conserved genetic architecture among populations of the maize progenitor, teosinte, was radically altered by domestication.

Very little is known about how domestication was constrained by the quantitative genetic architecture of crop progenitors and how quantitative genetic architecture was altered by domestication. Yang et al. [C.

Genome-wide association analysis of the strength of the MAMP-elicited defense response and resistance to target leaf spot in sorghum.

Plants have the capacity to respond to conserved molecular features known as microbe-associated molecular patterns (MAMPs). The goal of this work was to assess variation in the MAMP response in sorghum, to map loci associated with this variation, and to investigate possible connections with variation in quantitative disease resistance. Using an assay that measures the production of reactive oxygen species, we assessed variation in the MAMP response in a sorghum association mapping population known as the sorghum conversion population (SCP).

A Genome-Wide Association Study To Understand the Effect of Infection on Seedlings of a Maize Diversity Panel.

, which causes ear, kernel and stem rots, has been reported as the most prevalent species on maize worldwide. Kernel infection by results in reduced seed yield and quality as well as fumonisin contamination, and may affect seedling traits like germination rate, entire plant seedling length and weight. Maize resistance to is a quantitative and complex trait controlled by numerous genes with small effects.

Mapping of resistance to corn borers in a MAGIC population of maize.

Background: Corn borers constitute an important pest of maize around the world; in particular Sesamia nonagrioides Lefèbvre, named Mediterranean corn borer (MCB), causes important losses in Southern Europe. Methods of selection can be combined with transgenic approaches to increase the efficiency and durability of the resistance to corn borers. Previous studies of the genetic factors involved in resistance to MCB have been carried out using bi-parental populations that have low resolution or using association inbred panels that have a low power to detect rare alleles.

The genetic architecture of teosinte catalyzed and constrained maize domestication.

The process of evolution under domestication has been studied using phylogenetics, population genetics-genomics, quantitative trait locus (QTL) mapping, gene expression assays, and archaeology. Here, we apply an evolutionary quantitative genetic approach to understand the constraints imposed by the genetic architecture of trait variation in teosinte, the wild ancestor of maize, and the consequences of domestication on genetic architecture. Using modern teosinte and maize landrace populations as proxies for the ancestor and domesticate, respectively, we estimated heritabilities, additive and dominance genetic variances, genetic-by-environment variances, genetic correlations, and genetic covariances for 18 domestication-related traits using realized genomic relationships estimated from genome-wide markers.

A Genome Wide Association Study Reveals Markers and Genes Associated with Resistance to Infection of Seedlings in a Maize Diversity Panel.

infects maize, causing ear rot, yield loss and contamination by fumonisin mycotoxins. The fungus can be transmitted via kernels and cause systemic infection in maize. Maize resistance to the fungus may occur at different developmental stages, from seedling to maturity.

Collagen prolyl 4-hydroxylase 1 is essential for HIF-1α stabilization and TNBC chemoresistance.

Collagen prolyl 4-hydroxylase (P4H) expression and collagen hydroxylation in cancer cells are necessary for breast cancer progression. Here, we show that P4H alpha 1 subunit (P4HA1) protein expression is induced in triple-negative breast cancer (TNBC) and HER2 positive breast cancer. By modulating alpha ketoglutarate (α-KG) and succinate levels P4HA1 expression reduces proline hydroxylation on hypoxia-inducible factor (HIF) 1α, enhancing its stability in cancer cells.

QTL Mapping for Yield and Resistance against Mediterranean Corn Borer in Maize.

The Mediterranean corn borer (MCB), , is a major pest of maize, , in Mediterranean countries, inflicting significant kernel yield losses. For that reason, it necessary to know the genetic mechanisms that regulate the agronomic and resistance traits. A quantitative trait loci (QTL) mapping study for yield, resistance against MCB attack, and other relevant agronomic traits was performed using a recombinant inbred line (RIL) population derived from the cross A637 × A509 that is expected to segregate for yield, and ear, and stalk resistance to MCB.

QTL for Maize Midparent Heterosis in the Heterotic Pattern American Dent × European Flint under Corn Borer Pressure.

Despite the importance of heterosis and the efforts to comprehend this phenomenon, its molecular bases are still unknown. In this study, we intended to detect Quantitative trait loci (QTL) for mid-parent heterosis under infestation with the Mediterranean corn borer (MCB, Sesamia nonagrioides Lef.) using a North Carolina design III approach with a RIL population derived from a European flint inbred (EP42) × American dent inbred (A637) cross.

Modifications to a LATE MERISTEM IDENTITY1 gene are responsible for the major leaf shapes of Upland cotton (Gossypium hirsutum L.).

Leaf shape varies spectacularly among plants. Leaves are the primary source of photoassimilate in crop plants, and understanding the genetic basis of variation in leaf morphology is critical to improving agricultural productivity. Leaf shape played a unique role in cotton improvement, as breeders have selected for entire and lobed leaf morphs resulting from a single locus, okra (l-D), which is responsible for the major leaf shapes in cotton.

Hydroxycinnamate Synthesis and Association with Mediterranean Corn Borer Resistance.

Previous results suggest a relationship between maize hydroxycinnamate concentration in the pith tissues and resistance to stem tunneling by Mediterranean corn borer (MCB, Sesamia nonagrioides Lef.) larvae. This study performs a more precise experiment, mapping an F2 derived from the cross between two inbreds with contrasting levels for hydroxycinnamates EP125 × PB130.

Identification of QTL for resistance to Mediterranean corn borer in a maize tropical line to improve temperate germplasm.

Background: A QTL mapping study for maize resistance to the Mediterranean corn borer (MCB) was performed with a RIL population derived from the cross B73 × CML103. To develop commercial inbreds of maize resistant to the MCB for use in Europe, it would be useful to transfer resistance from tropical germplasm like the subtropical inbred CML103 to temperate lines. The inbred B73 was chosen as representative of the Stiff Stock heterotic group, a major heterotic group used in hybrid grown in both North American and Europe.

Genome-wide association study reveals a set of genes associated with resistance to the Mediterranean corn borer (Sesamia nonagrioides L.) in a maize diversity panel.

Background: Corn borers are the primary maize pest; their feeding on the pith results in stem damage and yield losses. In this study, we performed a genome-wide association study (GWAS) to identify SNPs associated with resistance to Mediterranean corn borer in a maize diversity panel using a set of more than 240,000 SNPs.

Results: Twenty five SNPs were significantly associated with three resistance traits: 10 were significantly associated with tunnel length, 4 with stem damage, and 11 with kernel resistance.

Should Histologic Grade Be Incorporated into the TNM Classification System for Small (T1, T2) Node-Negative Breast Adenocarcinomas?

Prognosis of invasive ductal carcinoma (IDC) strongly correlates with tumor grade as determined by Nottingham combined histologic grade. While reporting grade as low grade/favorable (G1), intermediate grade/moderately favorable (G2), and high grade/unfavorable (G3) is recommended by American Joint Committee on Cancer (AJCC) staging system, existing TNM (Primary Tumor/Regional Lymph Nodes/Distant Metastasis) classification does not directly incorporate these data. For large tumors (T3, T4), significance of histologic grade may be clinically moot as those are nearly always candidates for adjuvant therapy.

Secondary angiosarcoma of the breast: can imaging findings aid in the diagnosis?

Secondary angiosarcomas, although rare, are aggressive tumors that can develop in breast tissue that has undergone prior radiation therapy. We present three cases of secondary angiosarcoma of the breast in the setting of prior breast irradiation. Imaging findings include cutaneous nodules and progressive skin or trabecular thickening in an area of the breast separate from the patient's original breast carcinoma.

Size of sentinel node tumor deposits and extent of axillary lymph node involvement: which breast cancer patients may benefit from less aggressive axillary dissections?

Background: In most breast cancer series, nearly 30% to 40% of all patients are sentinel node positive; however, in a large proportion of these, the disease is limited to three or fewer positive nodes. On the basis of these observations, the object of this study is to identify a subset of patients who might benefit from a less aggressive axillary dissection, without compromising staging or local disease control. We reviewed known clinicopathologic variables associated with a higher risk for axillary metastasis in 467 patients who underwent sentinel node mapping at our institution.

Ultrasound-guided fine-needle aspiration of clinically negative lymph nodes versus sentinel node mapping in patients at high risk for axillary metastasis.

Background: Sonographically directed fine-needle aspiration is a less invasive and less costly alternative to sentinel node (SN) mapping in breast cancer patients at high risk for metastatic disease but with clinically negative axillae.

Methods: Radiographic, cytological, and histological diagnostic data on breast primary tumors from 114 consecutive SN candidates were prospectively assessed for clinicopathologic variables associated with an increased incidence of axillary metastases. Patients in whom these variables were identified underwent sonographic examination of their axillae followed by fine-needle aspiration when abnormal nodes were detected.

Sentinel node micrometastasis in breast carcinoma may not be an indication for complete axillary dissection.

The decision whether to proceed with complete axillary node dissection based on sentinel node status is clear for patients with negative or macrometastatic disease. However, the course of action based on sentinel node micrometastasis remains controversial. We reviewed 358 cases from 6/1999 to 7/2003.