Inheritance of aluminum tolerance in maize

Abstract

Backcrosses Dominance effects Epistasis F2 generations General and specific combining abilities Heterosis ReIative seminal root length Zea mays '-' Summary The inheritance of AI tolerance in maize (Zea mays L.) was studied in nutrient solution. Analysis of relative seminal root lengths of six generations (P" P2, F" F2, BC" and BCJ derived from crosses between tolerant and non-tolerant inbred !ines showed that additive gene effects contributed most to genetic variation for AI tolerance of the materiaIs included in this study. Dominance effects accounted for only half as much variation as did additive effects. Effects of epistasis contributed !ittle compared to other gene effects. The frequency distributions of plants within the F2 generations were continuous, unimodal, and typical for quantitatively inherited traits. There was some tendency for non-tolerance to be dominant over tolerance, but it was not consistent. In a diallel cross among inbred lines, lhe analysis of F, crosses indicated that lhe variance for general combining ability explained most of the variation, but specific combining abi!ity was statistically sigriificant in each case.

Eficiência de índices fenotípicos de comprimento de raiz seminal na avaliação de plantas individuais de milho quanto à tolerância ao alumínio

“…Estas plantas foram acondicionadas em casa de vegetação, sobre bandejas de plástico contendo 8,5 litros de solução nutritiva com 6 ppm de Al na forma de KAl(SO 4 ) 2 (Magnavaca, 1982), sob oxigenação constante. Durante os sete dias de condução do experimento, realizaram-se, em todas as bandejas, leituras de pH da solução nutritiva, a cada dois dias.…”

“…Existem, entretanto, várias metodologias para avaliação da tolerância ao Al (Rhue & Grogan, 1977;Garcia et al, 1979;Magnavaca, 1982). Principalmente no caso das gramíneas, há um consenso de que características baseadas no desenvolvimento do sistema radicular são os melhores crité-rios para a avaliação da tolerância.…”

Duplicate and Conquer: Multiple Homologs ofPHOSPHORUS-STARVATION TOLERANCE1Enhance Phosphorus Acquisition and Sorghum Performance on Low-Phosphorus Soils

“…Full complementary DNA sequences were obtained for Sb07g002840, Sb03g031670, Sb03g031690, and Sb07g006765. Reverse transcription-PCR of SbPSTOL1 genes was undertaken with root tissues from the sorghum line, BR007, after 13 d in nutrient solution (Magnavaca et al, 1987) with low P (2.5 mM P) as described for root morphology analysis. Roots were collected, and total RNA was isolated using the RNeasy Plant Mini Kit (Qiagen; http:// www.qiagen.com/).…”

“…After 4 d, uniform seedlings were transferred to moistened blotting papers placed into paper pouches (24 3 33 3 0.02 cm) as described by Hund et al (2009). Each experimental unit consisted of one pouch (three seedlings per paper pouch), whose bottom 3 cm was immersed in containers filled with 5 L of the nutrient solution described by Magnavaca et al (1987) with a P concentration of 2.5 mM (as phosphate; 10 pouches per container). The nutrient solution was changed every 3 d, and the pH was maintained at 5.6.…”

“…This mesh system serves to constrain the roots but not impede their growth. The mesh systems were placed into clear glass cylinders or in large polyethylene tank containers filled with nutrient solution as described by Magnavaca et al (1987) with 2.5 mM P and maintained at pH 5.6. The containers were kept under continuous aeration in a growth chamber with 27°C/20°C day/night temperatures and a 12-h photoperiod.…”