Biochemical characteristics associated with the development of the desiccation-Sensitive seeds of machilus thunbergii sieb. & zucc
Journal
Annals of Botany
Journal Volume
76
Journal Issue
4
Pages
381 - 387
Date Issued
1995
Author(s)
Chen, Mei-Huei
Abstract
Biochemical properties, i.e. endogenous abscisic acid, proline, sugars, respiration, adenosine phosphates and adenylate energy charge, and growth and moisture content were measured during the development of seeds of Machilus thunbergii. As dry matter accumulated in the embryo during development, moisture content, ABA, proline, respiration and sugars all declined. At maturity, the dry mass of the seeds failed to attain a plateau before the period of natural seed shedding; the axis and cotyledons reached moisture contents of 58 and 45%, respectively. Drying of immature seeds at 73% relative humidity and 25 °C for 30 d resulted in a complete loss of viability at all developmental stages tested with the exception of mature seeds that were able to tolerate a 5% decrease in moisture content before germination declined. ABA was detected in all embryos tested, with a maximum value 16.·16 µg g-1 d. wt about midway through development. Although the presence of ABA induced no tolerance to desiccation of mature seeds, it did coincide with decreased content of water in the developing seeds and decreased respiration. Desiccation damage of M. thunbergii seeds occurred when moisture content was still high (45%) and this damage was not related to the absence of oligosaccharides in the mature seeds. We conclude that developing embryos and mature seeds of M. thunbergii have properties common to many recalcitrant seeds, with seeds being sensitive to desiccation at all stages, having a prominent ABA peak, little proline, lacking oligosaccharides, and specifically, little dormancy and a moderate rate of respiration of mature seeds (0·9 µmol O2 min-1 g-1 f. wt). Adenosine triphosphate content and energy charge decreased from stage four to stage eight of seed development, then increased again to 103 nmol g-1 d. wt and 0·73, respectively, in mature seeds. The moderate energy charge observed in mature seeds indicates that continuous metabolism is also a characteristic of recalcitrant seeds.Copyright 1995, 1999 Academic Press
SDGs
Type
journal article