Scientists have revealed the mechanism of communication between the "internal and external barriers" of sweet orange fruit.

Original title: Scientists reveal the "internal and external barrier" communication mechanism of sweet orange fruits
Newell umbilical oranges and their mutant physiques and developmental waxy changes. Horticultural Research
recently published the latest results of the team of Cheng Yunjiang, a professor at Huahua Agricultural University. They described the effects of wax synthesis reduction on membrane lipid
metabolism
, and discovered 93 key structures
gene
gene
and transcription factors that affect the synthesis of wax and lipid paths in
citrus
.
citrus is an important fruit tree whose fruit and leaf surface are rich in wax and essential oils. Wax layer is very important to the citrus tree body and fruit to resist drought, prevent excessive loss of water, prevent the invasion of pathogens, extend storage life, improve the luster and freshness of fruit. Citrus fruit wax is mainly composed of ultra-long chain fatty acids and their derivatives, including aldehydes, alkanes, fatty acids, etc., they form a crystal structure in accordance with a certain proportion, distributed on the surface of the fruit, forming the fruit and the environment of the "external barrier."
is mainly composed of lipids, such as single semi-lactose diamide glycemine (MGDG), bi-lactose diamyl glycemine (DGDG) and phosphatidyl glyceli (PG) Body membranes, as well as cell membrane systems consisting of phosphatidylcholine (PC) and phosphatidylethanolamine (PE), maintain cell morphology, prevent cell moisture loss, and ensure photocoporization, which is an important "internal barrier" for plant bodies.
previous studies of different plant wax mutants have shown that the synthesis of ultra-long chain fatty acids is blocked and the flow of lipid metabolism is significantly altered, but the effects of this change on the phospholipids and glycolipids that make up the membrane system are rarely reported.
The team described the effects of wax synthesis reduction on membrane lipid metabolism through a joint analysis of wax assays, lipid histology, and transcriptional histology of New Holland umbilical orange (WT) and its bright mutant, Minnan 1 (MT).
the authors first found that mutant wax synthesis is inhibited during development, and the degree of inhibition becomes more pronounced as the fruit matures. Further experiments show that the decrease of MT wax synthesis is accompanied by a significant increase in lipid content of 36 carbon numbers during fruit ripening.
Based on the significant increase in chlorophylate hydrolytic products found in mutants and the increase in jasmine acid content, the authors conclude that in mutants, in order to maintain the steady state of lipids in the body, elevated lipids activate the lipid hydrolytic pathway, thus making the jasmine acid content increase.
subcellular location and tobacco instantaneous hyper-expression of the three phospholipidase genes (CsDALL4, CsDAD1, and CSDALL2) with significantly increased expression were found, all of which were located in chlorophylate, consistent with hydrolyte lipid function. Among them, CsDAD1 and CSDALL2 can significantly reduce the lipid content of some physiques after over-expression and promote the significant accumulation of jasmine acid. The hydrolysis process of phosphatase is a speed limiting step for jasmine acid synthesis, so CSDAD1 and CsDALL2 may be the key genes in sweet oranges that control jasmine acid synthesis.
this study provides a new perspective for the study of lilipid natural variation in plants, especially fruit trees, and lays a molecular foundation for the cultivation and storage performance improvement of new varieties of citrus.
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