Natal Antonio Vello

E6, a dominant gene conditioning early flowering and maturity in soybeans

Inheritance was studied in natural variants of the soybean cultivar Parana, developed under photoperiodic conditions ranging from 13 h 31 min day light, at sowing, to 14 h 23 min, 59 days afterwards. Results indicated that early flowering and maturity are controlled by a single dominant gene. Natural mutations that originated cultivars Paranagoiana and SS-1 occurred at the same locus of cultivar Parana. It was not possible to determine if the recessive alleles of these mutant cultivars are different. The designation E6 was proposed for the alleles determining earliness in cultivar Parana, and e6 for the gene determining late flowering and maturity in cultivars Paranagoiana and SS-1, until the individuality of the alleles of Paranagoiana and SS-1 is confirmed.

Variabilidade e correlações entre caracteres em cruzamentos de soja

A estimacao de parâmetros em geracoes iniciais de endogamia tem importância para direcionar o programa de melhoramento, principalmente em relacao ao processo de selecao dos genotipos mais promissores. Este trabalho avaliou 21 genotipos de soja (seis parentais e 15 combinacoes dialelicas em F2), em dois locais (ESALQ e Anhembi) de Piracicaba, SP. O delineamento usado foi em blocos ao acaso, com seis repeticoes por local. A parcela experimental foi de 12 covas de plantas individuais espacadas de 0,80 m x 0,80 m. Os caracteres avaliados foram numero de dias e altura da planta no florescimento e maturidade; valor agronomico; produtividade de graos; teor de oleo na semente e produtividade de oleo. Todas as estimativas de parâmetros basearam-se nos componentes das analises de variância e covariância individuais e conjuntas. Parentais e F2 apresentaram variabilidade para todos os caracteres. Em termos de qualidade ambiental favoravel, os dois locais foram bons para a expressao do potencial genetico dos genotipos, no entanto, o local Anhembi foi mais favoravel para produtividade de graos. A interacao genotipos x locais mostrou-se um importante componente da variacao fenotipica, com excecao do carater teor de oleo. As correlacoes genotipicas foram geralmente maiores que as fenotipicas e de ambiente nos dois locais. A magnitude das correlacoes fenotipicas e genotipicas mostrou que o fenotipo refletiu satisfatoriamente o genotipo. Os caracteres relacionados ao florescimento e a maturidade mostraram-se importantes para o melhoramento da produtividade, com destaque para o valor agronomico. Existe evidencia de dificuldades em obter novos genotipos produtivos e precoces.

Genetic diversity among Brazilian soybean cultivars based on SSR loci and pedigree data

Locos microssatelites e dados de genealogia foram utilizados para avaliar a diversidade genetica de um grupo de 168 cultivares brasileiras de soja. Os dezoito locos utilizados apresentaram em media 5,06 alelos por loco e coeficiente de diversidade genetica medio de 0,58. O dendrograma final resultante da matriz de distância genetica de Roger modificado por Wright, apresentou boa concordância com a ancestralidade dos grupos formados. Tambem foi estimado os coeficientes de parentesco entre as cultivares, sendo observada variacao de 0 a 1 com media de 0,18, enquanto que as similaridades para os locos microssatelites (1- GD) variou de 0,01 a 0,90 com media de 0,25. A correlacao entre as duas matrizes obtidas determinada pelo teste Z de Mantel apresentou valor baixo, 0,31, mas significativo (p<0,001). Os resultados obtidos sugerem que os locos microssatelites aliados as informacoes de genealogia proporcionam melhor analise da diversidade genetica de cultivares de soja.

Adaptabilidade e estabilidade de linhagens experimentais de soja selecionadas para caracteres agronômicos através de método uni-multivariado

This research studied the genotype x environment interaction (G x E), the adaptability and phenotypic stability, by applying AMMI (Additive Main Effects and Multiplicative Interaction Analysis) method for evaluating seed yield of soybean lines in F10 and F11 generations. The material included three populations derived from a 4 x 4 partial diallel having four insect resistant parents (IAC-100, Crockett, Lamar, D72-9601-1) and other four parents (BR-6, IAS-5, Davis, Ocepar-4) which are early and have high seed yield. In the F2 generation it were used three procedures of plant selection: PCI, population derived from F2 plants under total control of insects; PRIM and PRIS, populations obtained from F2 plants after the selection for resistance to leaf-feeder (defoliating) and pod-feeder (stink bug complex) insects, respectively. From F3 to F11, it was performed selection for seed yield and photoperiod tolerance among progenies. Twenty four experiments were carried out in randomized complete block design with two replications subdivided in sets with common checks, by testing the three populations in eight environments (E1 to E8): two locations (Anhembi, Areao), two agriculture years (1999/2000, 2000/2001), and two management systems (CII: intensive control of insects; CEI: ecological control of insects). Each experiment included 40 and 20 lines from a population in 1999/2000 and 2000/2001 respectively. Based on seed yield, it was concluded that: the AMMI method evidenced large percentage of high yielding and stable lines in all three populations: 70% in PCI, 65% in PRIS, and 55% in PRIM; the Anhembi location showed higher seed yield in all situations; for the three populations, among the environments with high seed yield, the AMMI method classified E1 (Anhembi, 1999/2000, CII) and E6 (Anhembi, 2000/2001, CEI) as the most stable and unstable environment respectively; lines with superior adaptability and stability originated from the following parents: IAC-100, D72-9601-1, BR-6, Davis, and IAS-5; outstanding biparental crosses occurred when the IAC-100 parent was crossed with IAS-5, Davis, OCEPAR-4 and BR-6.

Heterosis in soybeans for seed yield components and associated traits

The objective of this research was to quantify heterosis of agronomic traits and evaluate direct and indirect correlations among seed yield and other traits. A diallel involving six parents was grown in two localities. Seed yield (PG), one-hundred seed weight (PCS), number of pods per plant (NV), weight of aerial part of the plant (PPA), harvest index (IC) and number of seeds per pod (NGV) were evaluated. Positive values of heterosis were detected for all traits. Estimates of heterosis components were significative for most traits, showing effects of aditivity and dominance. The specific heterosis was more important than the variety heterosis, mainly in the locality Anhembi. MTBR-95-123800 presented the best potential per se and as parent in crosses, but it was excelled by some of the hybrids in the two localities. Number of pods per plant demonstrated to be suitable for indirect selection for PG.

Heritability and correlations among traits in four-way soybean crosses

Recurrent selection programs can use several crossing arrangements to synthesize basic populations for breeding purposes. This study evaluated heritability and correlations among traits in forty-five populations of F2[4] and F2:3[4] generations obtained throughout four-way crosses [4] between two dialells among ten semi-late and ten late maturity soybean (Glycine max L. Merrill) genotypes. The generation advance was made by the TSHD (Thinned Single Hill Descent) method and all individual plants were evaluated for the following traits: number of days to flowering (NDF) and maturity (NDM), plant height at flowering (PHF) and maturity (PHM), agronomic value (AV) and seed yield (YLD). Four-way crosses associated with TSHD method provided high genetic variability in the populations with little or no reduction from F2[4] to F2:3[4]. The ‘narrow sense’ heritability estimated using correlations between F2[4] and F2:3[4] plants was lower than but closely related to broad-sense estimates. The populations 21(IAC-4 × IAC-9) × (GO79-1039 × Paranagoiana) and 23 (IAC-4 × Santa Rosa) × (GO79-1039 × Tropical) were the most productive with high variability in F2[4] and/or F2:3[4] generations. Genotypic correlations measured were generally high, positive and consistent for the two generations except for those related to AV and YLD. These results indicate that the use of four-way crosses can be an efficient method to increase the genetic base of populations for recurrent selection or cultivar development. Significant AV × YLD correlations indicated visual selection can be used as additional selection criteria for improving populations.

Análise AMMI da produtividade de grãos em linhagens de soja selecionadas para resistência à ferrugem asiática

Abstract – The objective of this work was to quantify the effects of genotype x environment (GxE) interaction on grain yield in soybean progenies pre-selected for resistance to Asian soybean rust ( Phakopsora pachyrhizi ). Twelve trials evaluating progenies (lines F 6 and F 7 ) were carried out in different environments (combination of locations, years, and fungicide treatments to control late season diseases, including or not rust). Additive main effects and multiplicative interaction (AMMI) analysis captured, as GxE interaction pattern, 57% of the variance associated with the residues of non-additivity, of which 44% were retained in the firstprincipal component of interaction, and the remainder in the second. The firstcomponent was associated with the differences between the years of evaluation, which denotes unpredictability. The second component, however, was associated with different crop managements, related to the control or not of the diseases. Among genotypes with wide yield adaptability, the USP 02-16.045 and USP 10-10 lineages stood out.Index terms:

ESTIMATIVAS DE PARÂMETROS GENÉTICOS DE POPULAÇÕES DE SOJA EM SOLOS CONTRASTANTES NA SATURAÇÃO DE ALUMÍNIO

This paper reports results from the evaluation of 900 F7:6 inbred lines of soybean [Glycine max (L.) Merrill], derived from 45 diallel crosses, 20 of each one, and ten parental genotypes: FT-Cristalina, EMGOPA-301, IAC-4, IAC-5, IAC-6, IAC-8, IAC-9, IAC-11, Santa Rosa, and SS-1. The experiments were carried out in two localities (Anhembi and Areao Experimental Stations, Piracicaba county, State of Sao Paulo, Brazil), contrasting for aluminium saturation; Anhembi showed high aluminium saturation (>Al) whereas Areao showed low saturation (<Al). Four traits were evaluated: seed yield (PG), days to maturity (NDM), plant height at maturity (APM) and agronomic value (VA). The VA character was evaluated through a visual score considering: pod number, plant height, vigor, lodging, leaf retention, pod dehiscence, and disease symptoms. It was used an augmented design with 20 blocks, each one with 45 lines (regular treatment) and the ten parental genotypes as checks (common treatment); the experimental plot consisted of one row with length of 2.0 m x 0.5 m between row. The augmented design proved to be easily implemented in this phase, where many progenies were tested but few seeds were available. The effect of aluminium saturation on the means of the genetics parameters was dependent on the genotype and the character considered. The heritability estimates for the set of 900 lines were respectively in Anhembi and Areao: 0.58 and 0.84 for NDM; 0.64 and 0.62 for APM; 0.50 and 0.36 to VA; 0.38 and 0.38 to PG. Three crosses involving EMGOPA-301 with FT-Cristalina, IAC-4 e Santa Rosa, exceeded by having superior values of heritability for PG, in both localities, relatively to the set of 900 lines tested. In Anhembi, the genotypic correlations between number of days to maturity (NDM), plant height (APM), agronomic value (VA) and grain yield (PG) at F7:6 inbred lines level varied from 0.54 to 0.95 and they were superior in relation to phenotypic ones. The VA/PG genotypic correlation was distinguished (0.82), indicating that VA could be used for indirect selection of seed yield. Thus, for initial tests, the VA is of advantage, specially when having many entries in evaluation.

Genetic structure and a selected core set of brazilian soybean cultivars

Soybean is one of the most valuable and profitable oil crop species and a thorough knowledge of the genetic structure of this crop is necessary for developing the best breeding strategies. In this study, a representative collection of soybean cultivars recommended for farming in all Brazilian regions was genotyped using 27 simple sequence repeat (SSR) loci. A total of 130 alleles were detected, with an average allelic number of 4.81 per locus. These alleles determined the core set that best represented this soybean germplasm. The Bayesian analysis revealed the presence of two clusters or subgroups within the whole collection (435 soybean cultivars) and the core set (31 entries). Cultivars of similar origin (ancestral) were clustered into the same groups in both analyses. The genetic diversity parameters, based on the SSR loci, revealed high similarity between the whole collection and core set. Differences between the two clusters detected in the core set were attributed more to the frequency of their ancestors than to their genetic base. In terms of ancestry, divergent groups were presented and a panel is shown which may foster efficient breeding programs and aid soybean breeders in planning reliable crossings in the development of new varieties.

Successful crosses between fungal-resistant wild species of Arachis (section Arachis) and Arachis hypogaea

Peanut (Arachis hypogaea) is the fifth most produced oil crop worldwide. Besides lack of water, fungal diseases are the most limiting factors for the crop. Several species of Arachis are resistant to certain pests and diseases. This study aimed to successfully cross the A-genome with B-K-A genome wild species previously selected for fungal disease resistance, but that are still untested. We also aimed to polyplodize the amphihaploid chromosomes; cross the synthetic amphidiploids and A. hypogaea to introgress disease resistance genes into the cultivated peanut; and analyze pollen viability and morphological descriptors for all progenies and their parents. We selected 12 A-genome accessions as male parents and three B-genome species, one K-genome species, and one A-genome species as female parents. Of the 26 distinct cross combinations, 13 different interspecific AB-genome and three AA-genome hybrids were obtained. These sterile hybrids were polyploidized and five combinations produced tetraploid flowers. Next, 16 combinations were crossed between A. hypogaea and the synthetic amphidiploids, resulting in 11 different hybrid combinations. Our results confirm that it is possible to introgress resistance genes from wild species into the peanut using artificial hybridization, and that more species than previously reported can be used, thus enhancing the genetic variability in peanut genetic improvement programs.