Vol. 10, Special Issue 12 (2021)

Author(s):
PN Jagadev and VK Khanna

Abstract:
The Obturator, a transmitting tissue between the stigma and the ovary plays a critical role in controlling the direction of pollen tube entry into the ovary and was related to the release of chemotactic substances like carbohydrates, proteins and callose at the base of the style and in the ovary wall. Immediately after Selfing of the wheat cultivars viz. Chinese Spring (CS) and Hope, insoluble carbohydrates were produced in the extra-ovarian region and in the Obturator, through which the pollen tube had to pass. In CS x rye, the situation was similar to that in selfings. But the crosses between Hope and rye, during the initial hours after pollination, there was no staining in the Obturator region although there was uniform light staining of the extra-ovarian region resulting in loss or reduction of seed set. The secretion of protein was delayed in the Obturator of Hope x rye crosses as compared to CS x rye and the selfings of CS and Hope. It thus seems that once pollen tube movement is delayed in the initial period after pollination, fertilization may be prevented due to lack of secretion of proteins resulting in reduced or no seed set in Hope x rye. In selfings and CS x rye crosses, Callose was not present till 72 h after pollination, but callose was present in the entire ovary region in Hope x rye crosses, which prevents the pollen tube growth.