A novel adenylate isopentenyltransferase 5 regulates shoot branching via the ATTTA motif in Camellia sinensis

Abstract

Background Shoot branching is one of the important agronomic traits affecting yields and quality of tea plant (Camellia sinensis). Cytokinins (CTKs) play critical roles in regulating shoot branching. However, whether and how differently alternative splicing (AS) variant of CTKs-related genes can influence shoot branching of tea plant is still not fully elucidated. Results In this study, five AS variants of CTK biosynthetic gene adenylate isopentenyltransferase (CsA-IPT5) with different 3′ untranslated region (3ˊ UTR) and 5ˊ UTR from tea plant were cloned and investigated for their regulatory effects. Transient expression assays showed that there were significant negative correlations between CsA-IPT5 protein expression, mRNA expression of CsA-IPT5 AS variants and the number of ATTTA motifs, respectively. Shoot branching processes induced by exogenous 6-BA or pruning were studied, where CsA-IPT5 was demonstrated to regulate protein synthesis of CsA-IPT5, as well as the biosynthesis of trans-zeatin (tZ)- and isopentenyladenine (iP)-CTKs, through transcriptionally changing ratios of its five AS variants in these processes. Furthermore, the 3′ UTR AS variant 2 (3AS2) might act as the predominant AS transcript. Conclusions Together, our results indicate that 3AS2 of the CsA-IPT5 gene is potential in regulating shoot branching of tea plant and provides a gene resource for improving the plant-type of woody plants.

Overexpression of ZmIPT2 gene delays leaf senescence and improves grain yield in maize

“…CRISPR/Cas9 targeted gene knockout Phtheirospermum japonicum (Pj)IPT1a inhibits parasite induced CTK response in host, revealing the important role of PjIPT1a in Arabidopsis phloem-induced CTK response ( Greifenhagen et al, 2021 ). In the transgenic Camellia sinensis containing IPT5 , the 3’ UTR variant 2 (3AS2) was found to be the main transcript which participated in the regulation of tea axillary bud germination and shoot branching, providing gene resources for improving the plant type of woody plants ( Zhang et al, 2021 ). In addition, the triple mutant of TaIPT8-5a/5b/5d showed a decreased t-Z type CTK level and reduced drought tolerance under both normal and drought conditions.…”

Expression and functional analysis of CsA-IPT5 splice variants during shoot branching in Camellia sinensis

“…Designing and verification of the gene-specific quantitative real-time PCR (qPCR) primers for CsA-IPT5 splice variants and total transcripts can be found in our recent study ( Zhang et al, 2021 ). Ten primers were designed based on the 5ˊand 3ˊ UTRs of the CsA-IPT5 transcripts and listed in Table 1 .…”

“…As described in our recent report ( Zhang et al, 2021 ), total RNA from tea plant tissues was extracted and reverse transcribed. The qPCR assay was performed using the ABI 7500 Real-Time PCR system (Applied Biosystems, Foster City, CA, United States) with Power SYBR Green PCR Master Mix.…”

“…In summary, based on our recent study (Zhang et al, 2021), the current study further investigated the CsA-IPT5 AS-regulated post-transcriptional mechanisms of shoot branching. The results showed that in the above three shoot branching processes, the five splice variants may play regulatory roles through complementation or competition with each other.…”

“…We previously found that TIBA application after pruning could promote the formation of productive lateral branches in tea plants ( Zhang et al, 2017a ). Furthermore, we have found that CsA-IPT5 splice variants regulate shoot branching stimulated by 6-benzyladenine (6-BA) spraying or pruning in the tea plant ( Zhang et al, 2021 ). Given the key roles of Cs A-IPT5 transcripts in regulating tea plant shoot branching, here, we further investigated whether and how CsA-IPT5 splice variants regulate the above other three important processes, and thus find out which splice variants play key roles in the shoot branching of tea plants.…”