No abstract

The development of homozygous breeding lines in maize may be accelerated through the use of haploids. Thus, the obtaining and prior identification of haploids generated by the haploid inducer lines is an important factor. The purpose of this study was to identify haploids by flow cytometry and to correlate the nuclear DNA content to the morphological and morphometric traits of the seeds that gave rise to them. In addition, molecular markers were used to confirm the androgenetic nature of the haploid. The seeds obtained were derived from the cross between the inbred line W23 and the commercial hybrid P30F90. Among these seeds, a group was selected, putative haploids, whose embryo was white and the pericarp purplish. This group, consisting of 330 seeds, was characterized based on seed morphology, seed morphometry and nuclear DNA content. Flow cytometry analyses identified four haploids, and all of them were small size plants and had brittle leaves. The weight, length, thickness and width of the haploid seeds were very variable indicating that morphometric traits do not constitute reliable data for visual selection of haploid seeds. Based on results, the inbred line W23 induced haploid maize even under tropical conditions. Microsatellite molecular markers (SSR) proved to be efficient, confirming the androgenetic trait of the haploids.

-The efficiency of selection can be broadened for certain traits using estimative of genetic parameters, which are fundamental for plant breeding. The estimative of genetic parameters allows identifying the nature of the action of genes involved in the control of quantitative traits and evaluates the efficiency of different breeding strategies to obtain genetic gains. Therefore, this study aimed to verify the variability and correlation between morphological and agronomic traits in synthetic maize populations, in order to practice indirect selection. Thirteen populations were evaluated in field experiments at Jaboticabal-SP and Campo Alegre de Goiás-GO, using randomized block design, for lodging (LOD), culm breakage (CB), plant height (PH), ear height (EH) and grain yield (GY). The 13 populations were also sown in 1 kg-plastic bags under black shade cloth, using a randomized complete block design with nine replications, for evaluation of the morphological traits: main root length (MRL), root fresh matter (RFM), root dry matter (RDM), average root diameter (ARD), root surface area (RSA), root tissue density (RTD) and shoots dry matter (SDM). The trait GY exhibited genetic variability enough to be effective if used for selection. The selection on the morphological traits is indicated on RDM, due to the ease in obtaining data and its accuracy, high correlation with all morphological traits and association with GY. The simultaneous selection based on RFM and RDM, for gains in GY, can be performed. The highest direct effect on GY was identified in LOD and CB, being indicated for indirect selection.Key words: Zea mays. Phenotypic correlation. Genetic parameters. Direct selection.RESUMO -A eficiência de seleção pode ser ampliada para determinado caráter utilizando-se estimativas de parâmetros genéticos, as quais são fundamentais no melhoramento de plantas, uma vez que permitem identificar a natureza da ação dos genes envolvidos no controle de caracteres quantitativos e avaliar a eficiência de diferentes estratégias de melhoramento para a obtenção de ganhos genéticos. Assim, objetivou-se verificar a existência de variabilidade e correlação entre caracteres agronômicos e morfológicos em populações sintéticas de milho, visando seleção indireta. Foram utilizadas 13 populações, avaliadas em experimentos de campo em Jaboticabal-SP e Campo Alegre de Goiás-GO, utilizando-se o delineamento em blocos casualizados, para acamamento (AC), quebramento de colmos (QUE), altura de plantas (AP), altura de espiga (AE), e produção de grãos (PG). As 13 populações também foram semeadas em sacos plásticos de 1 kg sob sombrite, utilizando-se delineamento em blocos casualizados com nove repetições, para avaliação das seguintes características morfológicas: comprimento da raiz principal (CR), matéria fresca de raiz (MFR), matéria seca de raiz (MSR), diâmetro médio de raiz (DMR), área de superfície da raiz (ASR), densidade de tecido radicular (DTR) e matéria seca da parte aérea (MSPA). O caráter PG apresentou grande variabilidade genéti...

Sorghum [Sorghum bicolor (L.) Moench] is the fifth most important cereal crop globally by harvested area and production. Its drought and heat tolerance allow high yields with minimal input. It is a promising biomass crop for the production of biofuels and bioproducts. In addition, as an annual diploid with a relatively small genome compared to other C4 grasses, and excellent germplasm diversity, sorghum is an excellent research species for other C4 crops such as maize. As a result, an increasing number of researchers are looking to test the transferability of findings from other organisms such as Arabidopsis thaliana and Brachypodium distachyon to sorghum, as well as to engineer new biomass sorghum varieties. Here, we provide an overview of sorghum as a multipurpose feedstock crop which can support the growing bioeconomy, and monocot research model system. We review what makes sorghum such a successful crop and identify some key traits for future improvement. We assess recent progress in sorghum transformation and highlight how transformation limitations still restrict its widespread adoption. Finally, we summarize available sorghum genetic, genomic, and bioinformatics resources. This review is intended for researchers new to sorghum research, as well as those wishing to include non-food and forage applications into their research.