Title: Integrated analyses of phenotype, phytohormone, and transcriptome to elucidate the mechanism governing internode elongation in two contrasting elephant grass (Cenchrus purpureus) cultivars

Authors: Yan Qi, Li Jie, Lu Liyan, Gao Lijuan, Lai Dawei, Yao Na, Yi Xianfeng, Wu Zhuyue, Lai Zhiqiang, Zhang Jiyu*

Journal: Industrial Crops and Products

Impact factor: IF₂₀₂₀ = 5.645

Abstract: In view of the global energy crisis and climate change, elephant grass (Cenchrus purpureus (Schumach.) Morrone syn. Pennisetum purpureum Schumach.) represents a useful lignocellulosic biofuel feed stock due to its high biomass yield and persistence. Internode elongation is an important factor that affects the productivity of energy grass. Elucidating the molecular mechanism governing internode elongation may facilitate the development of molecular improvement strategies for energy grass, but this mechanism has not been thoroughly investigated in elephant grass to date. In this study, the phenotypic evaluation of six cultivars of elephant grass showed that the plant height positively correlated with internode length, rather than internode number. The dwarf cultivar C. purpureus cv. Mott (CpMott) and the tall cultivar C. purpureus cv. GuiMinYin (CpGMY) exhibited significantly different plant height and internode length but not internode number. Analyses of transcription profiles and gibberellin concentrations from the shoot tips of the two cultivars showed that the endogenous bioactive gibberellin A₁ (GA₁) concentrations was markedly decreased whilst some of representative gibberellin biosynthetic enzymes were downregulated in the CpMott, such as GA20-oxidase (GA20ox) and ent-kaurene synthase (KS). Exogenous application of gibberellin A₃ (GA₃) indicated that CpMott is a gibberellin-sensitive dwarf cultivar. In addition, the gibberellin-deficiency of CpMott reduced the lignin content by inhibiting the transcript levels enzyme genes in lignin biosynthesis, while induced the expression levels of genes related to abiotic stress. Overall, our results may serve to elucidate the molecular mechanism underlying elephant grass internode elongation and facilitate the development of thus grass into a more efficient energy source.

Linkage: https://doi.org/10.1016/j.indcrop.2021.113693