02775naa a2200313 a 450000100080000000500110000800800410001902400510006010000180011124502210012926000090035052017040035965000120206365000210207565000210209665000370211765300260215465300320218065300170221265300240222970000230225370000210227670000200229770000200231770000220233770000180235970000170237777300670239421034882019-12-09       2019    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1007/s11738-018-2804-72DOI1 aPOLESI, L. G.  aChloroplast ultrastructure and hormone endogenous levels are differently affected under light and dark conditions during in vitro culture of Guadua chacoensis (Rojas) Londoño & P. M. Peterson.h[electronic resource]  c2019  aGuadua chacoensis (Poaceae) is a woody bamboo native from the Atlantic forest biome. Morphogenetic and physiological studies are scarce in bamboos, and tissue culture-based biotechnologies tools can be used to investigate ultrastructure and physiological processes as well as to mass-propagate specific genotypes. This study evaluated the effect of light and dark conditions on chloroplast biogenesis as well as in the endogenous levels of zeatin (Z), abscisic acid (ABA), gibberellic acid (GA4), and jasmonic acid (JA) during in vitro culture of G. chacoensis. An increase was observed, followed by a decrease in starch content in response to light treatment, and in contrast, in darkness, an accumulation of starch which is associated to amyloplast formation at day 30 was observed. No etioplast formation was observed even in the dark and this was associated with the presence of fully developed chloroplast at the beginning of the experiment. Z levels quantified showed distinct behavior, as in light, no difference in the levels was observed, except at day 10, and in darkness, the levels increased along the evaluation time. ABA, GA4, and JA biosynthesis increased along the time of evaluation in light condition. In contrast, in darkness, the levels remained unaltered, excepted for an increase in JA levels at day 10, suggesting a strong relationship between light and these phytohormone levels. Possible reasons why light’s presence and absence cause changes in chloroplast ultrastructure and hormone endogenous levels in in vitro cultivated culms of G. chacoensis are discussed. Keywords Bamboos · Micropropagation · Transmission electron microscopy · Plant physiology · Phytohormone  aBamboos  aMicropropagation  aPlant physiology  aTransmission electron microscopy  aAtlantic forest biome  aGuadua chacoensis (Poaceae)  aPhytohormone  aWoody bamboo native1 aFRAGA, H. P. F. de1 aVIEIRA, L. do N.1 aHERINGER, A. S.1 aORNELLAS, T. S.1 aSANTOS, H. P. dos1 aGUERRA, M. P.1 aPESCADOR, R.  tActa Physiologiae Plantarumgv. 41, n. 10, p. 1-12, Jan. 2019.