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Drought drastically affects plant growth, development and productivity. Plants respond to drought stress by enhancing sugar accumulation and water transport. Homeodomain‐leucine zipper (HD‐Zip) transcription factors (TFs) participate in various aspects of plant growth and stress response. However, the internal regulatory mechanism of HD‐Zips in moso bamboo (Phyllostachys edulis) remains largely unknown. In this study, we identified an HD‐Zip member, PeHDZ72, which was highly expressed in bamboo shoots and roots and was induced by drought. Furthermore, PeSTP_46019, PeSWEET_23178 and PeTIP4‐3 were identified as downstream genes of PeHDZ72 in moso bamboo by DAP‐seq. The expressions of these three genes were all induced by drought stress. Y1H, DLR and GUS activity assays demonstrated that PeHDZ72 could bind to three types of HD‐motifs in the promoters of these three genes. Overexpression of PeHDZ72 led to a remarkable enhancement in drought tolerance in transgenic rice, with significantly improved soluble sugar and sucrose contents. Meanwhile, the expressions of OsSTPs, OsSWEETs and OsTIP were all upregulated in transgenic rice under drought stress. Overall, our results indicate that drought stress might induce the expression of PeHDZ72, which in turn activated downstream genes PeSTP_46019, PeSWEET_23178 and PeTIP4‐3, contributing to the improvement of cellular osmotic potential in moso bamboo in response to drought stress. Summary statement: Drought stress triggers intricate signalling networks that impact plant growth. This study presents PeHDZ72, which serves as a regulatory factor to activate downstream genes of PeSTP_46019, PeSWEET_23178 and PeTIP4‐3, contributing to the improvement of cellular osmotic potential in moso bamboo in response to drought stress. [ABSTRACT FROM AUTHOR]

ROOTHAIRLESS (RHL) is a typical type of basic helix‐loop‐helix (bHLH) transcription factor (TF), which has been reported to participate in various aspects of plant growth and in response to stress. However, the functions of RHL subfamily members in moso bamboo (Phyllostachys edulis) remain unknown. In this study, we identified 14 bHLH genes (PeRHL1–PeRHL14) in moso bamboo. Phylogenetic tree and conserved motif analyses showed that PeRHLs were clustered into three clades. The expression analysis suggested that PeRHL4 was co‐expressed with PeTIP1‐1 and PePHT1‐1 in moso bamboo. Moreover, these three genes were all up‐regulated in moso bamboo under drought stress and phosphate starvation. Y1H, DLR and EMSA assays demonstrated that PeRHL4 could activate the expression of PeTIP1‐1 and PePHT1‐1. Furthermore, overexpression of PeRHL4 could increase both drought and phosphate starvation tolerance in transgenic rice, in which the expression of OsTIPs and OsPHT1s was significantly improved, respectively. Overall, our results indicated that drought stress and phosphate starvation could induce the expression of PeRHL4, which in turn activated downstream genes involved in water and phosphate transport. Collectively, our findings reveal that PeRHL4 acting as a positive regulator contributes to enhancing the tolerance of moso bamboo under drought stress and phosphate starvation. Summary statement: Drought stress and phosphate starvation trigger intricate signalling networks that impact plant growth. This study presents PeRHL4 as a regulatory factor to activate downstream genes for water and phosphate transport, potentially bolstering the tolerance of moso bamboo under stresses. [ABSTRACT FROM AUTHOR]

Summary: Water plays crucial roles in expeditious growth and osmotic stress of bamboo. Nevertheless, the molecular mechanism of water transport remains unclear.In this study, an aquaporin gene, PeTIP4‐3, was identified through a joint analysis of root pressure and transcriptomic data in moso bamboo (Phyllostachys edulis). PeTIP4‐3 was highly expressed in shoots, especially in the vascular bundle sheath cells. Overexpression of PeTIP4‐3 could increase drought and salt tolerance in transgenic yeast and rice.A co‐expression pattern of PeSAPK4, PeMYB99 and PeTIP4‐3 was revealed by WGCNA. PeMYB99 exhibited an ability to independently bind to and activate PeTIP4‐3, which augmented tolerance to drought and salt stress. PeSAPK4 could interact with and phosphorylate PeMYB99 in vivo and in vitro, wherein they synergistically accelerated PeTIP4‐3 transcription. Overexpression of PeMYB99 and PeSAPK4 also conferred drought and salt tolerance in transgenic rice.Further ABA treatment analysis indicated that PeSAPK4 enhanced water transport in response to stress via ABA signaling. Collectively, an ABA‐mediated cascade of PeSAPK4‐PeMYB99‐PeTIP4‐3 is proposed, which governs water transport in moso bamboo. [ABSTRACT FROM AUTHOR]

Fructose-1,6-bisphosphate aldolase (FBA) is a pivotal enzyme in various metabolic pathways, including glycolysis, gluconeogenesis, and the Calvin cycle. It plays a critical role in CO2 fixation. Building on previous studies on the FBA gene family in Moso bamboo, our study revealed the biological function of PeFBA6. To identify CSN5 candidate genes, this study conducted a yeast two-hybrid library screening experiment. Subsequently, the interaction between CSN5 and PeFBA6 was verified using yeast two-hybrid and LCI experiments. This investigation uncovered evidence that FBA may undergo deubiquitination to maintain glycolytic stability. To further assess the function of PeFBA6, it was overexpressed in rice. Various parameters were determined, including the light response curve, CO2 response curve, and the levels of glucose, fructose, sucrose, and starch in the leaves of overexpressing rice. The results demonstrated that overexpressed rice exhibited a higher saturation light intensity, net photosynthetic rate, maximum carboxylation rate, respiration rate, and increased levels of glucose, fructose, and starch than wild-type rice. These findings indicated that PeFBA6 not only enhanced the photoprotection ability of rice but also improved the photosynthetic carbon metabolism. Overall, this study enhanced our understanding of the function of FBA and revealed the biological function of PeFBA6, thereby providing a foundation for the development of excellent carbon fixation bamboo varieties through breeding. [ABSTRACT FROM AUTHOR]