Morphological and endogenous phytohormone changes during long-term embryogenic cultures in Korean pine

Abstract

Somatic embryogenesis (SE) is a biotechnological tool with high application potential for in vitro propagation and regeneration of conifers species. However, in SE of Korean pine, a dominant species of the natural mixed coniferous and broadleaf forests of the temperate forests in Northeast China, decreasing embryogenic potential was found in embryogenic callus (EC) with successive subcultures, especially when the cultures were maintained for more than 5-6 months, which is one of the most signi cant problems preventing commercial implementation of the SE technique. Aiming to investigate the morphological and the endogenous phytohormone changes associated with the decreasing embryogenic potential of Korean pine, here, we compared seven types of calli during long-term embryogenic culture. It was found that both the external morphological characteristics and internal cell structure were signi cantly different among the different types of calli. Speci cally, similar to their zygotic counterparts of conifer trees, the calli with high embryogenic potential were characterized by a higher number of designated proembryogenic masses (PEMs) structure. In addition, surface of this types of callus was covered with a large amount of mucilaginous extracellular matrix (ECM), which could further differentiate into globular embryos containing the embryonal masses (EM) and embryonic tube (ET) structure.In contrast, in those low embryogenic potential calli, we observed disintegrated PEMs structure, a large amount of irregularly shaped cells, and degraded cells, which failed to form somatic embryos. The endogenous hormone results showed that high levels of ABA were bene cial for promoting early somatic embryo differentiation in Korean pine, but maintaining high embryogenic potential required moderate levels of IAA and low levels of ZR. Additionally, a high ratio of IAA / ABA and MeJA / ABA was conducive to maintaining high embryogenic potential, whereas a low ratio of IAA / ABA and MeJA / ABA were effective for early somatic embryos morphological differentiation. This study demonstrates morphological and physiological characteristics of the embryogenesis potential of Korean pine calli.

Plant Regeneration via Organogenesis in Jerusalem Artichokes and Comparative Analysis of Endogenous Hormones and Antioxidant Enzymes in Typical and Atypical Shoots

“…The results are in agreement with the results reported by Liang et al [29], who found that considerable differences in endogenous hormone levels were measured between normal and abnormal types of embryos in grapevine (Vitis vinifera). Similar results were also obtained in Pinus koraien, and substantial changes in endogenous hormones were found among the different types of calli [28].…”

“…Auxins, cytokinins, gibberellins, abscisic acid, and ethylene are commonly considered to be the main natural plant hormones. Recently, the effects of the endogenous hormone content on in vitro culture responses have been studied in a variety of plant species, such as Tulbaghia simmleri [27], Pinus koraiensis [28], and Vitis vinifera [29]. The morphogenetic abilities are different in different explant types, which may be attributed to the differences in their endogenous hormone content [28,30].…”

“…Recently, the effects of the endogenous hormone content on in vitro culture responses have been studied in a variety of plant species, such as Tulbaghia simmleri [27], Pinus koraiensis [28], and Vitis vinifera [29]. The morphogenetic abilities are different in different explant types, which may be attributed to the differences in their endogenous hormone content [28,30]. Under in vitro culture conditions, the explant differentiation, plant regeneration, and physiological processes are modulated by the interaction of the PGRs and endogenous hormones [23,27].…”

Effects of Long-Term Subculture on Maturation Ability and Plant Conversion in Pinus radiata: Using FT-IR Spectroscopy to Determine Biomarkers of Embryogenic Tissue Aging

“…To date, there have been different theories on the possible mechanisms associated with the loss of yield in the maturation phase, in addition to the damage that could be generated because of handling during subculturing. Although, in some species, ET can multiply in culture media free of PGRs [50], the vast majority require a complex network of interactions between endogenous and exogenous PGRs, mainly auxins and cytokinins, during the early pro-embryogenic stages and ethylene, gibberellic, and abscisic acids later in the development of Se [11,51,52]. Therefore, prolonged exposure to these regulators, mainly 2.4-D auxin, could generate an imbalance in their transport or synthesis, which could cause problems in the following stages [14,19,53].…”

ENDOGENOUS HORMONES FROM THE YOUNG LEAVES OF OIL PALM (Elaeis guineensis Jacq.): A RESPONSE TO In Vitro CALLUS AND EMBRYOID INDUCTION

“…The combination of various types of endogenous hormones collaborated in the formation of potential embryoids. The high content of ABA helped in embryo differentiation, while the addition of low IAA and zeatin maintained the embryogenic potential in Korean pine callus (Liang et al, 2022). The content of endogenous hormones ABA, IAA, and GA 3 in Ormosia henryi Prain.…”