Avaliação de populações de milho de alta qualidade protéica

Twenty-three high quality protein maize populations, selected for hard-endosperm opaque-2 through modifiers of the opaque-2 gene, and two normal checks (BR 105 and AG 301), were evaluated at six Brazilian environments: Porto da Folha, SE (Summer), Porto da Folha, SE (Winter), Sete Lagoas, MG, Goiânia, GO, Nova Prata, RS and Cruz Alta, RS. The following traits were measured: ear weight (kg/ha), grain endosperm protein (%), tryptophan and lysine (% of endosperm protein). Opaque-2 white kernel high quality protein maize populations showed good adaptation to the different regions, high yields and tryptophan-lysine content similar to floury endosperm opaque-2 cultivars. A few yellow kernel populations showed good adaptation with high yields but need to be improved in tryptophan-lysine content.Vinte e três populações de milho de alta qualidade protéica, contendo o gene recessivo opaco-2 em homozigose, selecionadas para endosperma vítreo através de modificadores do gene opaco-2 e duas testemunhas de endosperma normal (BR 105 e AG 301), foram avaliadas em seis ambientes: Porto da Folha, SE (verão), Porto da Folha, SE (inverno), Sete Lagoas, MG, Goiânia, GO, Nova Prata, RS e Cruz Alta, RS. Os caracteres utilizados neste estudo foram: peso de espiga (kg/ha), proteína (%), triptofano, lisina (% na proteína do endosperma). Algumas populações opaco-2 brancas de endosperma vítreo adaptaram-se bem a diferentes regiões do País, apresentando alta produtividade e teores de lisina e triptofano na proteína do endosperma equivalente a tipos contendo o gene opaco-2 com endosperma farináceo. Algumas populações de cor de grãos amarelos mostraram boa produtividade, mas precisam ser melhoradas em seus teores de lisina e triptofano.

Adaptability and stability evaluation of maize hybrids using Bayesian segmented regression models.

The occurrence of genotype by environment interaction (G x E), which is defined as the differential response of genotypes to environmental variation, is frequently reported in maize cultures, making it challenging to recommend cultivars. Methods allowing to study the potential nonlinear pattern of genotype responses to environmental variation allied to prior beliefs on unknown parameters are interesting to evaluate the phenotypic adaptability and stability of genotypes. In this context, the present study aimed to assess the adaptability and stability of maize hybrids, by using the Bayesian segmented regression model, and evaluate the efficacy of using informative and minimally informative prior distributions for the selection of cultivars. Randomized complete-block design experiments were carried out to study the yield (kg/ha) of 25 maize hybrids, in 22 different environments, in Northeastern Brazil. The Bayesian segmented regression model fitted using informative prior distributions presented lower credibility intervals and Deviance Criterium of Information values, compared to those obtained by fitting using minimally informative distributions. Therefore, the model using informative prior distributions was considered for the adaptability and stability evaluation of maize genotypes. Once most northeastern farmers in Brazil have limited capital, the genotype P4285HX should be considered for planting, due to its high yield performance and adaptability to unfavorable environments

mTOR pathway somatic variants and the molecular pathogenesis of hemimegalencephaly

ObjectivesRecently, defects in the protein kinase mTOR (mammalian target of rapamycin) and its associated pathway have been correlated with hemimegalencephaly (HME). mTOR acts as a central regulator of important physiological cellular functions such as growth and proliferation, metabolism, autophagy, death, and survival. This study was aimed at identifying specific variants in mTOR signaling pathway genes in patients diagnosed with HME.MethodsUsing amplicon and whole exome sequencing (WES) of resected brain and paired blood samples from five HME patients, we were able to identify pathogenic mosaic variants in the mTOR pathway genes MTOR, PIK3CA, and DEPDC5.ResultsThese results strengthen the hypothesis that somatic variants in PI3K-Akt-mTOR pathway genes contribute to HME. We also describe one patient presenting with a pathogenic variant on DEPDC5 gene, which reinforces the role of DEPDC5 on cortical structural changes due to mTORC1 hyperactivation. These findings also provide insights into when in brain development these variants occurred. An early developmental variant is expected to affect a larger number of cells and to result in a larger malformation, whereas the same variant occurring later in development would cause a minor malformation.SignificanceIn the future, numerous somatic variants in known or new genes will undoubtedly be revealed in resected brain samples, making it possible to draw correlations between genotypes and phenotypes and allow for a genetic clinical diagnosis that may help to predict a given patient's outcome