Main content area

RcPAL, a key gene in lignin biosynthesis in Ricinus communis L.

Lu, Jiannong, Shi, Yuzhen, Li, Weijin, Chen, Sen, Wang, Yafei, He, Xiaolin, Yin, Xuegui
BMC plant biology 2019 v.19 no.1 pp. 181
Ricinus communis, amino acids, biosynthesis, castor beans, castor oil, disease resistance, gene overexpression, genes, genetically modified organisms, insect pests, leaves, lignin, lignin content, lodging, mechanical damage, metabolites, plant height, quantitative polymerase chain reaction, risk, staining, xylem
BACKGROUND: Castor (Ricinus communis L.) is an important seed oil crop. Castor oil is a highly demanded oil for several industrial uses. Current castor bean varieties suffer from low productivity and high risk of insect pests and diseases. High productive and pest/disease resistance varieties are needed. Lignin has been associated to the resistance for pest, disease and lodging. Lignin is produced from several metabolites of the phenylpropanoid pathway. PAL is the key enzyme of the phenylpropanoid pathway. The gene PAL may assist in the improvement of resistance of castor bean. RESULTS: The RcPAL CDs was amplified and its function was examined by transgenic overexpression and antisense expression, lignin histochemical staining, real-time PCR, lignin content measurement and morphological investigation. Its full length was 2145 bp, encoding 714 amino acids. The overexpression of RcPAL (7.2 times) increased significantly the PAL activity, dyeing depth of xylem cells and lignin content (14.44%), resulting in a significantly lower plant height, deeper and thicker blade, more green leaves, shorter internode, thicker stem diameter, and opposite in antisense expression plants (lignin content lowered by 27.1%), demonstrated that the gene RcPAL was a key gene in castor lignin biosynthesis. CONCLUSIONS: The gene RcPAL is a key gene in castor lignin biosynthesis and can be induced to express under mechanical damage stress. When up-regulated, it increased the lignin content significantly and dwarfed the plant height, and opposite when down-regulated. The gene RcPAL may assist in the improvement of resistance and plant type of castor bean.