Post-pollination biochemical changes in the floral organs of<Emphasis Type="Italic">Rhynchostylis retusa</Emphasis> (L.) Bl. and<Emphasis Type="Italic">Aerides multiflora</Emphasis> Roxb. (Orchidaceae) |
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Authors: | Lucky Kumar Attri Harsh Nayyar Ravinder Kumar Bhanwra Suraj Prakash Vij |
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Institution: | (1) Department of Biochemistry, University of Ibadan, Ibadan, Nigeria |
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Abstract: | If left unpollinated, the flowers ofAerides multiflora (Roxb.) andRhynchostylis retusa (L.) Bl. can remain fresh for 17 and 24 d, respectively. However, they begin to wilt at 2 to 3 days after pollination (DAP)
and 3 to 4 DAP, respectively, and become senescent at 5 DAP and 7 DAP, respectively. When measured at two developmental phases
— Stage 1, start of wilting and Stage 2, progression to senescence — all the floral organs from pollinated flowers had higher
contents of total soluble sugars, reducing sugars, and free amino acids than those from unpollinated flowers. A corresponding
increase was noted in the activities of hydrolytic enzymes, i.e., α-amylase, β-amylase, and invertase, and proteolytic enzymes
(proteases) in those organs. This indicated that signals related to pollination had up-regulated those activities, leading
to a breakdown of complex molecules into simpler ones for mobilization. The amounts of sugars and enzyme activity were relatively
greater in the pollinated flowers ofA. multiflora compared withR. retusa, and levels were always higher in the floral lips and perianths. When inhibitors of auxin (0.25 mM TIBA) or ethylene (0.25
mM AgNO2) were applied to the pollinated flowers, their senescence was partially prevented, thus signifying hormonal involvement in
governing the pollination-induced biochemical alterations normally found in those organs. |
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