Abstract.
Few biochemical and molecular details are available on microspore growth and development. In this work, a nuclease was partially purified from diffusates of barley (Hordeum vulgare L.) microspores by using concanavalin-A as ligand. The chromatographic preparation contained a 34-kDa protein with nucleolytic activity; the enzyme (called BMN: barley microspore nuclease) was very stable at pH>8.0 and temperatures below 50 °C. Activity was highest at pH 5.6 and increased almost exponentially with temperature until a breakpoint between activity and stability was reached at 70 °C. Although BMN was able to cleave RNA, the enzyme showed a remarkable preference for DNA, especially in the single-stranded form. The best homopolymeric substrates were poly(dA) and poly(A), whereas poly(dC), poly(G) and poly(I) were almost completely uncleaved. When incubated with intact nuclei, BMN caused a nucleosomal DNA ladder of approximately 200 bp. On the basis of DNA laddering, substrate specificity, Mg2+-dependence and best performance at apoplastic pH, BMN can be referred to as a putative apoptotic nuclease involved in pollen development.
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Marchetti, S., Zaina, G., Chiabà, C. et al. Isolation and characterization of an endonuclease synthesized by barley (Hordeum vulgare L.) uninucleate microspores. Planta 213, 199–206 (2001). https://doi.org/10.1007/s004250000507
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DOI: https://doi.org/10.1007/s004250000507