Boron concentration gradient in the endosperm and embryo during ovule development in Clivia miniata

Abstract

Research on boron concentration gradient in the endosperm and embryo of Clivia miniata Regel ovules is a continuation of investigations on polar distribution of several compounds in the developing ovule. The polar distribution of chemical compounds in the ovule might constitute one of the factors determining embryogenesis. It was found that: a) there occured a chalaza-micropyle gradient of boron concentration in the endosperm during the exponential phase of embryo growth (age of ovules - 50 to 120 days); boron concentration in the endosperm increased from 12.13 to 23.71 µg g^-1 fr.wt. (micropylar part) and from 13.58 to 28.42 µg g^-1 fr.wt. (chalazal part); the embryo elongated towards the chalazal part of the ovule, i.e. towards higher boron concentration in the endosperm; b) in the embryo a reversed gradient of boron was detected: a higher concentration in the micropylar part (decrease from 127.29 to 61.78 µg g^-1 fr.wt.; ovules 86-123 days old), a lower one in the chalazal part (decrease from 99.47 to 53.16 µg g^-1 fr.wt.; the exponential phase of embryo growth).