Genetic differentiation in Plantago major: Ca²⁺‐ and Mg²⁺‐stimulated ATPases from roots and their role in phenotypic adaptation

Abstract

The Mg2+‐ and Ca2+‐stimulated ATPase activities of the microsomal fractions of the roots of four inbred lines of Plantago major L. were followed at two levels of mineral nutrition. In addition the response of a transfer of plants from one condition to the other was studied. Kinetic properties of the ATPases (Km and Vmax) were calculated and used to differentiate between genetic differences among the inbred lines and the plasticity within each inbred line. The Vmax values of the ATPase activity differed significantly between the lines and were directly related to seed number per capsule (low Vmax→ 11 seeds per capsule, high Vmax→ 33 seeds per capsule). In addition, the Vmax values of the ATPase acitivty may be related to ecological strategy. Plasticity of enzyme activity is expressed in differences in the Vmax values of the ATPase activity, as a response to nutritional level or changes of the strength of the nutrient solution. Differences in this plasticity in the four selected lines and in rapidity of response to a change in mineral nutrition were directly related to the ecological strategy. These results are discussed in relation to the strategy of the genotypes for survival in the field. The presence of plasticity in line 4 (ssp. pleiospema) makes this genotype behave like an annual plant, following a ruderal strategy. The absence of plasticity in line 1 (ssp. major) fits a more competitive strategy.

Ca2+‐ AND MG2+‐STIMULATED ATPases FROM ROOTS OF PLANTAGO SPECIES: RESPONSE TO DIFFERENT LIGHT ENERGY FLUXES

“…The same inbred lines also possessed different degrees of plasticity for the same characteristics. In an inbred line with a low seed number per capsule, viz P. major ssp major, a complete absence of plasticity was observed (Kuiper, 1982(Kuiper, , 1983. These results together with observations on P. major ssp major in this paper strongly suggest, that genotypes of P. major ssp major (seed number per capsule is ca ten) have no plasticity at all, not even during germination.…”

“…Characteristics ofthe nitrogen metabolism and of the energy metabolism (Lambers et al, 1981 b) were also shown to be rigid. In comparable experiments the Ca^"^-and Mg^+-stimulated ATPase activity from roots of this species did not change when the supply of mineral nutrients to the plants was increased or decreased (Kuiper, 1982;Kuiper and Kuiper, 1979a). Such a phenotypic rigidity was also found for morphological characteristics of P. major ssp major by Warwick and Briggs (1980).…”

“…The strategy of these genotypes for survival in the fleld implies no possibility to cope with changing environmental factors. Genotypes with a higher seed number per capsule (> ten) show different degrees of plasticity (Kuiper 1982(Kuiper , 1983. Genotypes with a very high seed number per capsule {ca.…”

Plantago: A Multidisciplinary Study

“…Plants of four inbred lines, A3, GI, KI and Z2' were grown on two nutrient solutions, 100070 (114 strength Hoagland solution) and 2%; part of the plants were transferred from one to the other growth condition, halfway through the time of the experiment (Kuiper 1982). Plants of four inbred lines, A3, GI, KI and Z2' were grown on two nutrient solutions, 100070 (114 strength Hoagland solution) and 2%; part of the plants were transferred from one to the other growth condition, halfway through the time of the experiment (Kuiper 1982).…”

“…Plants of four inbred lines, A3, GI, KI and Z2' were grown on two nutrient solutions, 100070 (114 strength Hoagland solution) and 2%; part of the plants were transferred from one to the other growth condition, halfway through the time of the experiment (Kuiper 1982). A positive correlation between relative growth rate and the rapidity of the appearance of a plastic response (and completion of the plastic response) was demonstrated (Kuiper 1982 The results indicated that the involved genotypes probably typified a large scale of ecotype differentiation in P. major.…”