Global transcriptome analysis of alfalfa reveals six key biological processes of senescent leaves

Abstract

Leaf senescence is a complex organized developmental stage limiting the yield of crop plants, and alfalfa is an important forage crop worldwide. However, our understanding of the molecular mechanism of leaf senescence and its influence on biomass in alfalfa is still limited. In this study, RNA sequencing was utilized to identify differentially expressed genes (DEGs) in young, mature, and senescent leaves, and the functions of key genes related to leaf senescence. A total of 163,511 transcripts and 77,901 unigenes were identified from the transcriptome, and 5,133 unigenes were differentially expressed. KEGG enrichment analyses revealed that ribosome and phenylpropanoid biosynthesis pathways, and starch and sucrose metabolism pathways are involved in leaf development and senescence in alfalfa. GO enrichment analyses exhibited that six clusters of DEGs are involved in leaf morphogenesis, leaf development, leaf formation, regulation of leaf development, leaf senescence and negative regulation of the leaf senescence biological process. The WRKY and NAC families of genes mainly consist of transcription factors that are involved in the leaf senescence process. Our results offer a novel interpretation of the molecular mechanisms of leaf senescence in alfalfa.

Transcriptomic resources for prairie grass (Bromus catharticus): expressed transcripts, tissue-specific genes, and identification and validation of EST-SSR markers

“…We found 1,570 stem-speci c genes, among which those signi cantly enriched in the phenylpropanoid biosynthesis pathway might affect the feed value of B. catharticus, as phenylpropanoid metabolism is a major pathway of lignocellulose biosynthesis [7,25]. While we identi ed 3,030 leaf-speci c genes mainly related to the photosynthetic pathways, which might be of bene t in the improvement of leaf photosynthetic e ciency and biomass parameters, analysis of leaf transcriptome of alfalfa identi ed 5,133 DEGs and senescenceassociated pathways, including ribosome and phenylpropanoid biosynthesis, and starch and sucrose metabolism pathways, and suggested a novel interpretation of the molecular mechanisms of leaf senescence [26]. In addition, our comparative analysis showed that the ribosome pathway was the most signi cantly enriched pathway among 1,803 seed-speci c genes.…”

Transcriptomic resources for prairie grass (Bromus catharticus): expressed transcripts, tissue-specific genes, and identification and validation of EST-SSR markers

“…While we identified 3,030 leaf-specific genes mainly related to the photosynthetic pathways, which might be of benefit in the improvement of leaf photosynthetic efficiency and biomass parameters. Analysis of leaf transcriptome of alfalfa identified 5,133 DEGs and senescence-associated pathways, including ribosome and phenylpropanoid biosynthesis, and starch and sucrose metabolism pathways, and suggested a novel interpretation of the molecular mechanisms of leaf senescence [ 26 ]. In addition, our comparative analysis showed that the ribosome pathway was the most significantly enriched pathway among 1,803 seed-specific genes.…”

Primary metabolic processes as drivers of leaf ageing

“…1 ) [ 35 , 44 , 53 ]. Other basic metabolic changes that regulate senescence were reported in young and mature but not yet senescing leaves of both perennial and annual plants: for instance, downregulation of genes that are involved in amino acid biosynthesis and a decrease in the level of amino acids in developing Medicago sativa (alfalfa) and Arabidopsis leaves [ 6 , 35 , 54 ]. Likewise, in a recent study, age-related differences were observed in metabolites of leaves collected from perennial tea crop Camellia sinensis plants aged 8 and 25 years old [ 55 ].…”