Elongation of stigmatic papillae induced by heat stress is associated with disturbance of pollen attachment inArabidopsis thaliana

ABSTRUCT Heat stress can seriously impact on yield production and quality of crops. Many studies uncovered the molecular mechanisms that regulate heat stress responses in plants. Nevertheless, effects of heat stress on the morphology of plants were still not extensively studied. In this study, we observed the detailed morphological changes of reproductive organs in Arabidopsis thaliana caused by heat stress. Larger area of stigma, and shorter length of anthers, filaments and petals were observed in plants subjected to heat stress compared to those under controlled conditions. Scanning electron microscopy (SEM) observation showed that length of stigmatic papillae without pollens seemed to be longer than that with pollens. In addition, classification of stigmas based on pollen attachment patterns together with artificial pollination assay revealed that pollen attachment onto stigma was clearly decreased by heat stress, and indicated that heat induced elongation of stigmatic papillae might be associated with disturbance of pollen attachment onto stigma. Furthermore, histochemical staining experiments revealed that crosstalk between Ca 2+ and NO derived from pollens and O 2 − derived from stigma might be associated with morphological alteration of stigma.