Role of membrane lipid hydrolysis genes in the aroma formalion of Chinese white pear ‘Xiang Mian Li’

Pear is an economically important fruit worldwide. We recently reported a crispy texture pear cultivar ‘Xiang Mian Li’ (XML) with intense aroma as a good candidate for Chinese white pear breeding. Chinese white pears usually have faint odor, thus it's interesting to uncover the molecular mechanisms for the development of aroma in ‘XML’. Freshly plucked faint odor ‘XML’ fruit (XML-FA) and postharvest ripened fruit with intense aroma (XML-IA) were studied through RNA-Seq. A total of 3758 differentially expressed genes (DEGs) were found between XML-FA and XML-IA, which significantly enriched in 288 Gene Ontology (GO) terms and 101 KEGG pathways. Besides the expected “Plant hormone signal transduction” and “ethylene biosynthetic process”, changes in volatile biosynthesis related pathways were also found. Highly expressed LOX and lipase were found to be the most important genes involved in the characteristic aroma formation of ‘XML’, suggesting the great role of membrane lipid hydrolysis in the mechanism of aroma formation in ‘XML’ pear. Additionally, PDC2, ADH, FAD, PLD and 4CL were also closely related to the formation of ‘XML’ aroma. Our data can be applied to improve practically the breeding program for elite Chinese white pear cultivars.