Enzyme activity and histological analysis of the abscission zone of Elymus sibiricus

doi:10.11686/cyxb2017484

Abstract

Abstract: Histological and enzyme activity analysis of the abscission zone of seed from six Elymus sibiricus accessions from the northeast margin of the Qinghai-Tibet Plateau at different stages of seed maturation was undertaken. The results showed that the abscission layer of seeds were present before seed shattering. The abscission layer was composed of 2 to 3 layers of small volume cells, oval in shape and with a compact arrangement. The degree of lignification of these cells was higher than surrounding cells. The lignified cell number of low seed shattering accessions was higher than high seed shattering accessions; low seed shattering accessions did not have an abscission layer at the seed maturity stage. These accessions had a rough fracture surface and an integrated abscission layer structure. High seed shattering accessions developed a clear fracture or abscission layer during seed maturation. These materials had a smooth fracture surface and incomplete abscission layer structure. Changes in cellulase (CE) and polygalacturonase (PG) activity among accessions differed at different seed developmental stages. The activities of these cell wall hydrolases were both closely related to seed shattering; the CE and PG activity of high seed shattering accessions at the time of shattering was high and consistent with electron microscopy observations. The high seed shattering accession (XH09) possessed the highest enzyme activity (XH09_CE=479.52 IU·L^-1, XH09_PG=188.87 pg·mL^-1) during the seed shattering period while the low seed shattering accession (ZHN03) had the lowest enzyme activity. This study showed that there were clear differences in the degree of lignification of the abscission layer, fracture surface smoothness, structural integrity of the abscission layer and the activities of cell wall hydrolases between low and high seed shattering accessions during the critical period of seed shattering. The degree of lignification of the abscission layer and activities of cell wall hydrolases at the seed shattering stage were the most important factors influencing seed shattering in wild E. sibiricus accessions.

Key words: Elymus sibiricus, seed shattering, abscission zone, histological analysis, cell wall hydrolases

ZHANG Jun-chao, XIE Wen-gang, ZHAO Xu-hong, ZHANG Zong-yu, ZHAO Yong-qiang, WANG Yan-rong. Enzyme activity and histological analysis of the abscission zone of Elymus sibiricus[J]. Acta Prataculturae Sinica, 2018, 27(7): 84-92.

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