Positively selected amino acid replacements within the RuBisCO enzyme of oak trees are associated with ecological adaptations

Phylogenetic analysis by maximum likelihood (PAML) has become the standard approach to study positive selection at the molecular level, but other methods may provide complementary ways to identify amino acid replacements associated with particular conditions. Here, we compare results of the decision tree (DT) model method with ones of PAML using the key photosynthetic enzyme RuBisCO as a model system to study molecular adaptation to particular ecological conditions in oaks (Quercus). We sequenced the chloroplast rbcL gene encoding RuBisCO large subunit in 158 Quercus species, covering about a third of the global genus diversity. It has been hypothesized that RuBisCO has evolved differentially depending on the environmental conditions and leaf traits governing internal gas diffusion patterns. Here, we show, using PAML, that amino acid replacements at the residue positions 95, 145, 251, 262 and 328 of the RuBisCO large subunit have been the subject of positive selection along particular Quercus lineages associated with the leaf traits and climate characteristics. In parallel, the DT model identified amino acid replacements at sites 95, 219, 262 and 328 being associated with the leaf traits and climate characteristics, exhibiting partial overlap with the results obtained using PAML

Produtividade e classificação de brócolos para indústria em função da adubação nitrogenada e potássica e dos espaçamentos entre plantas Yield and classification of broccoli depending on fertilizing and spacing between plants

No município de Itatiba-SP, no período de março a julho de 2007, foi realizado um experimento com o objetivo de avaliar doses de nitrogênio e potássio e espaçamentos entre plantas na produtividade e classificação de brócolos para indústria. O experimento foi instalado sob delineamento de blocos ao acaso, com os tratamentos em esquema fatorial 5 x 4, e três repetições, sendo avaliadas as doses de nitrogênio-potássio: 105-105; 157,5-157,5; 210-210; 262,5-262,5 e 315-315 kg ha-1 de N e K2O e os espaçamentos entre plantas: 0,2; 0,3; 0,4 e 0,5 m. O espaçamento entre linhas foi de 0,8 m. Foram avaliados o teor foliar de nitrogênio (TN) e de potássio (TP), produtividade de inflorescência (PI), produtividade de floretes (PF), rendimento industrial (RI) e classificação dos floretes com base em seu comprimento: PF5 (<5 cm); PF57 (>5 e <7 cm); PF79 (>7 e <9 cm) e PF9 (>9 cm). Maiores espaçamentos entre plantas proporcionaram maior TN e menores PI e PF. As doses NK e os espaçamentos entre plantas não influenciaram significativamente o TP e o RI. As maiores produtividades de inflorescências (22,08 t ha-1) e de floretes (17,09 t ha-1) foram obtidas com 0,20 m entre plantas e 315 kg ha-1 de N e de K2O. Maior percentagem de floretes na classe PF5 foi obtida no menor espaçamento entre plantas. As doses NK e os espaçamentos entre plantas não influenciaram as percentagens de floretes nas classes PF79 e PF9.<br>In Itatiba, São Paulo state, Brazil, during the period between March and July of 2007, an experiment was carried out aiming to appraise the effect of doses of nitrogen and potassium (105-105, 157.5-157.5, 210-210, 262.5-262.5 and 315-315 kg ha-1 N and K2O) and spacing between plants (0.2, 0.3, 0.4 and 0.5 m) upon the yield of broccoli and their classification. The experimental design was carried out in a randomized block, with the treatments in a 5 x 4 factorial scheme and three replications. Rows of plants were 0.8 m apart. The following characteristics were evaluated: foliar content of nitrogen (N) and potassium (K), head yield (HY), florets yield (FY), industrial yield (IY) and classification of florets based on length: FY5 (<5 cm); FY57 (>5 and <7 cm); FY79 (>7 and <9 cm) and FY9 (>9 cm). The largest spacing between plants provided the highest N, but HY and FY were reduced. The NK dose and spacing between plants did not influence significantly the level of K and IY. The maximal HY (22.08 t ha-1) and FY (17.09 t ha-1) were obtained with 0.20 m between plants and 150% NK dose (315 kg ha-1 of N and K2O). The higher percentage of florets in FY5 was obtained with smaller spacing between plants and NK dose and spacing did not influence significantly the percentage of florets with lengths greater than 7 cm