دانلود رایگان مقاله انگلیسی انعطاف پذیری نرخ ترکیب میوزی در پاسخ به درجه حرارت رشادی - NCBI 2018

ABSTRACT

 Meiotic recombination shuffles genetic information from sexual species into gametes to  create novel combinations in offspring. Thus, recombination is an important factor in  inheritance, adaptation and responses to selection. However, recombination is not a static parameter; meiotic recombination rate is sensitive to variation in the environment, especially temperature. That recombination rates change in response to both increases and decreases in temperature was reported in Drosophila a century ago, and since then in several other species. But it is still unclear what the underlying mechanism is, and whether low and high temperature effects are mechanistically equivalent. Here we show that, as in Drosophila, both high and low temperatures increase meiotic crossovers in Arabidopsis thaliana. We show that, from a nadir at 18C, both lower and higher temperatures increase recombination through additional class I – interfering – crossovers. The increase in crossovers at high and low temperatures however appears to be mechanistically at least somewhat distinct, as they differ in their association with the DNA repair protein MLH1. We also find that, in contrast to what has been reported in barley, synaptonemal complex length is negatively correlated with temperature; thus, an increase in chromosome axis length may account for increased crossovers at low temperature in A. thaliana, but cannot explain the increased crossovers observed at high temperature. The plasticity of recombination has important implications for evolution and breeding, and also for interpreting observations of recombination rate variation among natural populations.

DISCUSSION

In this study, we demonstrate that male meiotic recombination rate increases at temperatures both above and below a nadir at 18˚C in the Col-0 strain of A. thaliana. We show that both the high and low temperature increase appear to result wholly or mostly from an increase in class I interfering crossovers, but that the high temperature and low temperature effects may be mechanistically at least somewhat distinct. The low temperature increase in HEI10- marked, but MLH1-negative foci may be explainable by a concomitant increase in axis length of about 14% at lower temperatures. At high temperatures, on the other hand, axis length decreases, and thus cannot explain an increase in MLH1 foci and recombination.