Figure 10.

The model shows the response of phyA (A) and phyB1B2 (B) mutations at different growth stages under heat stress (HS). The gray rectangles show the factors inhibited while the green rectangles illustrate the factors enhanced by stress application. The growth stages that were shortened in S, V, and Fl were the seed germination, vegetative growth, and flowering stages, respectively. The phy mutants exhibited tolerance to HS during S, V, and Fl stages. In S stage, the seed germination rates of both phy mutants were not significantly affected by HS compared to control conditions (A, B). In V stage, phyA enhanced the proline production, HSFs, GRP, and plant growth (A), while phyB1B2 enhanced the upregulation of HSFs and HSPs as well as plant growth (B). In addition, both phy mutants inhibited cell membrane injuries (A, B). In Fl stage, phy mutants enhanced pollen fertility for a longer time compared to WT (A, B). Moreover, phyA exhibited an increase in the percentage of developed flowers and an inhibition in the percentage of abnormal and stigma-exerted flowers compared to WT. During a long HS application in the Fl stage, phyA exhibited enhanced abnormal flower formation via downregulation of TAP3 which enhanced sepal and petal conversion (A).