Effects of high temperature stress on microsporogenesis and pollen production in sunflower

Abstract

Heat stress can affect pollen production as it may interrupt the process of microsporogenesis and prevent normal pollen development. The aim of this research was to investigate whether occurence of male sterile plants in a male fertile sunflower accession may be due to the heat stress during microsporogenesis. Male sterile and male fertile plants of an inbred line were analyzed by evaluating development of anthers, presence of pollen, pollen vitality and analysis of meiosis – microsporogenesis. Anthers of male sterile plants were poorly developed and without pollen while fertile plants had pollen vitality of 98%. Analysis of meiosis showed normal diakinesis with 17 bivalents in both sterile and fertile plants. However, the following phases were all with abnormalities in sterile plants (metaphase I 6-18%, anaphase I 6-10%, telophase II 32-46%), while in fertile plants abnormalities were also present but less expressed with 5, 1 and 20% respectively. After telophase II, microspores were found sporadiccaly but smaller than normal, deformed and without an exine.