Question
In the sieve elements, which one of the following is the most likely function of P-proteins?
Deposition of callose on sieve plates
Providing energy for active translocation
Autolytic enzymes
Sealing off mechanism on wounding
Solution
D.
Sealing off mechanism on wounding
In most angiospermic plants, sieve tube elements of phloem, are P-proteins. Later is found in all dictos and in many monocots but it is absent in gymnosperms and cryptogams. The main function of P-proteins is in sealing off damaged sieve elements by plugging up sieve plate pores.
