Cloning And Expression Analysis Of Lectin Gene In Litchi

Litchi is a famous tropical fruit, which has an important position in the tropical agricultural economy of China. But it also faces with the problem that pests and diseases undermine litch fruit at growing and harvest storing. Lectin is a special protein which has one or more catalytic domain, which could distinguish and bind with monosaccharide or oligosaccharides of cell surface. Thus, lectin can improve resistance of plants to diseases and pests. It is necessary to intensive study expression of lectin gene in litch to improve litchi productivity.Using Feizixiao, Nadaowuhe and Ziniangxi, difference of physiological characteristics changes was first investigated during storage. Lectin gene coding sequences and promoter regulatory sequence was then cloned and sequenced. On this basis of sequence, the relative quantity of lectin gene expression in the litchi was detected using quantitative PCR. Results are as follows:1) During storage, with the increased of pericarp browning degree, anthocyanin content decreased, the permeability increased, pH value increased, and incidence of a disease increased. Low temperature and bagging can delay the process of browning by reducing water loss rate of litchi fruit.2) Cloned the sequences of lectin gene cDNA and gDNA from litch. The cDNA full length sequence is 874bp, containing a complete open reading frame which seqence length is 468bp. The encoded protein has similar domain with jackfruit family lectin. A1300bp promoter sequences upper lectin gene 5'stream was cloned, which is rich of TATA box that often appear in Promoter's Active Components. A plant expression vector"pCAMBIA1302-lectin"was also successfully constructed.3) RT-PCR study showed that the expression of lectin gene is specific significant, the expression levels in stem and seeds are much higher than that in pulp. During growth and development of litch fruit, the expression level of lectin gene during early development slightly higher than the late. At senescence stage, the expression level of lectin gene showed a sharp increase with a short time.We summarize the important novel findings as follows:1) For the first time, successfully cloned the sequences of lectin gene from litch, and confirmed that litchi lectin was encoded by multiple gene family.2) A1300bp promoter sequences upper lectin gene 5'stream was cloned, and a plant expression vector"pCAMBIA1302-lectin"was also successfully constructed for the first time, which provide a basis for studying the subcellular localization of litch lectin and transgenosis.