Zingiber montanum (J.Koenig) Link ex A.Dietr is a perennial herb of the ginger of family Zingiaceae. It has dark red conical inflorescence and is of great ornamental value. Its inflorescence axis is short and soft, and can be improved by hybridization. In addition, the phylogenetic relationship of Zingiaceae has been controversial. However, there is relatively little research on the reproductive biology of Z. montanum. In order to promote the smooth progress of cross breeding and provide new evidences for the phylogeny of Zingiaceae, this study observed the development of macrospore, microspore, female and male gametophyte of ginger by paraffin method, monolithic tablet method and semi-thin sectioning so as to explore the reproductive biological anatomic characteristics of Z. montanum and provide theoretical basis for the conservation of Z. montanum. The main results are as follows: ① Z. montanum has two anther chambers and the tapetum is of periplasmodial, the mode of anther wall formation is basic type. ② Cytokinesis of microsporocyte meiotic division is of successive type, tetradsarebilateral, linear and T-shape type, the mature pollen grains are two-celled. ③ The ovule is anatropous double integuments and crassinucellate. Embryo sac is of polygonum type. ④ The corresponding relationship between male and female gametophyte development was recorded, the maturity time of the two are synchronized, but microspore mother cells start meiosis earlier than macrospore mother cells. For the first time, we found that the tapetum type in the anther wall of Zingiber montanum is periplasmodial tapetum, which differs from the characteristics reported in other Zingiberaceae plants by previous researchers. The research results can provide a strong scientific basis for the breeding of Zingiaceae plants and their systematic classification.

Hesperidin is a dihydroflavonoids, accounting for more than 50% of the total flavonoids in Citri Reticulatae Pericarpium (CRP) of traditional Chinese medicine. It is an effective antioxidant and free radical scavenger that has anti-inflammatory, antiviral and hypoglycemic properties. The latest studies reported that hesperidin has a potential for novel coronavirus resistance. However, little is known about the synthesis regulation and accumulation site of hesperidin in plants. In this study, hesperidin synthase gene Crc1, 6RhaT was cloned, and the protein can be completely transformed flavanone-7-O-glucoside into hesperidin in vitro and in vivo. Studies on biological characteristics of ovary walls and exocarps showed that the relative expression levels of the Crc1, 6RhaT gene and protein decreased gradually with the development of citrus fruits, and the relative content of hesperidin firstly increased, then sequentially decreased. In situ hybridization results further revealed that Crc1, 6RhaT transcription was mainly concentrated in the secretory cavity cells, which are revealed to be the site of flavonoid synthesis. Immunocytochemistry localization results showed that the Crc1,6RhaT was mainly located in the endoplasmic reticulum, nucleus and vacuole of secretory cells. We inferred that the Crc1,6RhaT was synthesized in the endoplasmic reticulum, then was transported into the vacuoles through enlarged vesicles at the end of the endoplasmic reticulum. Our results not only revealed that Crc1,6RhaT may be involved in the synthesis of hesperidin of the main bioactive substance in the medicinal plant Citrus reticulata ‘Chachi’ fruit, but also provided novel insights into the main subcellular sites of hesperidin biosynthesis in vacuoles.