Transcriptome profiling of postharvest shoots identifies PheNAP2- and PheNAP3-promoted shoot senescence

Abstract

The juvenile shoots of Phyllostachys edulis have been used as a food source for thousands of years, and it is recognized as a potential source of nutraceuticals. However, its rapid senescence restricts bamboo production and consumption, and the underlying molecular mechanisms of rapid shoot senescence remain largely unclear. In the present study, transcriptome profiling was employed to investigate the molecular regulation of postharvest senescence in shoots, along with physiological assays and anatomical dissections. Results revealed a distinct shift in expression postharvest, specifically transitions from cellular division and differentiation to the relocation of nutrients and programmed cell death. A number of regulatory and signaling factors were induced during postharvest senescence. Moreover, transcription factors, including NAM, ATAF and CUC (NAC) transcription factors, basic helix–loop–helix transcription factors, basic region/leucine zipper transcription factors, MYB transcription factors and WRKY transcription factors, were critical for shoot postharvest senescence, of which NACs were the most abundant. PheNAP2 and PheNAP3 were induced in postharvest shoots and found to promote leaf senescence in Arabidopsis by inducing the expression of AtSAG12 and AtSAG113. PheNAP2 and PheNAP3 could both restore the stay-green Arabidopsis nap to the wild-type phenotype either under normal growth condition or under abscisic acid treatment. Collectively, these results suggest that PheNAPs may promote shoot senescence. These findings provide a systematic view of shoot senescence and will inform future studies on the underlying molecular mechanisms responsible for shoot degradation during storage.

Peer Review #2 of "Overexpression of PheNAC3 from moso bamboo promotes leaf senescence and enhances abiotic stress tolerance in Arabidopsis (v0.1)"

“…At the same time, PheNAC3 was also upregulated during post-harvest senescence of bamboo shoots. The transcript level was positively correlated with the rate of loss of moisture, peroxidase activity, and catalase activity, and negatively correlated with lipoxygenase activity and phenylalanine ammonia-lyse activity (Li et al, 2019). Therefore,…”

“…According to the physiological and biochemical changes during the senescence of harvested shoots, sharp transitions occurred at 12 h and 24 h, as compared to 0 h (Li et al, 2019).…”

Overexpression of PheNAC3 from moso bamboo promotes leaf senescence and enhances abiotic stress tolerance in Arabidopsis

“…At the same time, PheNAC3 was also upregulated during post-harvest senescence of bamboo shoots. The transcript level was positively correlated with the rate of loss of moisture, peroxidase activity, and catalase activity, and negatively correlated with lipoxygenase activity and phenylalanine ammonia-lyse activity (Li et al, 2019). Therefore, PheNAC3 participates in the regulation of post-harvest senescence of bamboo shoots.…”

“…S4B). According to the physiological and biochemical changes during the senescence of harvested shoots, sharp transitions occurred at 12 and 24 h, as compared to 0 h (Li et al, 2019). Additionally, the detached shoots become inedible after being stored for 24 h. Therefore, four representative storage time points (0, 12, 24 and 48 h) were selected to analyze the relative expression pattern of PheNAC3.…”

“…However, Li et al (2015) and Chen & Ding (2013) did not conduct an in-depth analysis of their functions. Up to now, only the study of Li et al (2019) indicates that PheNAP2 and PheNAP3 belong to NAP subgroup (which promote leaf senescence) and were involved in the meristem senescence process in harvested bamboo. The ectopic expression of PheNAP2 and PheNAP3 promotes leaf senescence in Arabidopsis.…”