OsNAC2 encoding a NAC transcription factor that affects plant height through mediating the gibberellic acid pathway in rice

Abstract

These authors contributed equally to the work. SUMMARYPlant height and flowering time are key agronomic traits affecting yield in rice (Oryza sativa). In this study, we investigated the functions in rice growth and development of OsNAC2, encoding a NAC transcription factor in rice. Transgenic plants that constitutively expressed OsNAC2 had shorter internodes, shorter spikelets, and were more insensitive to gibberellic acid (GA 3 ). In addition, the levels of GAs decreased in OsNAC2 overexpression plants, compared with the wild-type. Moreover, flowering was delayed for approximately 5 days in transgenic lines. The transcription of Hd3a, a flowering-time related gene, was suppressed in transgenic lines. In addition, transgenic Arabidopsis plants expressing OsNAC2 were also more insensitive to GA 3 . The expression levels of GA biosynthetic genes OsKO2 and OsKAO were repressed. The expression of OsSLRL, encoding a repressor in the GA signal pathway, and OsEATB, which encodes a repressor of GA biosynthesis, were both enhanced. Western blotting indicated that DELLA also accumulated at the protein level. Dual-luciferase reporter analyses, yeast one-hybrid assays and ChIP-qPCR suggested that OsNAC2 directly interacted with the promoter of OsEATB and OsKO2. Taken together, we proposed that OsNAC2 is a negative regulator of the plant height and flowering time, which acts by directly regulating key genes of the GA pathway in rice.

A Rice NAC Transcription Factor Promotes Leaf Senescence via ABA Biosynthesis

“…4 and 7). Similarly, Chen et al (2015) reported that OsNAC2 repressed the expression of GA biosynthetic genes, OsKO2, and enhanced the expression of OsEATB, which encodes a repressor of GA biosynthesis (Chen et al, 2015). Additionally, MYC2, a basic helix-loop-helix domaincontaining TF, acts as both activator and repressor to modulate the expression jasmonic acid-responsive genes in Arabidopsis (Dombrecht et al, 2007).…”

“…To study the role of OsNAC2 in leaf senescence, we examined the senescence symptoms of transgenic lines, including 35S::OsNAC2 lines (OsNAC2-OX, ON7, and ON11) and knockdown lines (OsNAC2-RNAi18, RNAi25, and RNAi31), which were previously reported (Chen et al, 2015). The third leaves of 6-week-old seedlings hydroponically cultivated were used for statistics of yellowing rate.…”

“…The vector in which 1,500-bp full-length promoter of OsNAC2 is connected with GUS was as described by Shen et al (2017). Overexpression and RNAi transgenic lines were constructed before and the details are described by Chen et al (2015). The seeds of OsNAC2-OX, wild-type, and OsNAC2-RNAi plants were germinated in petri dishes with wetted filter paper at 37°C under dark condition.…”

“…Previous study of our lab showed that overexpression of OsNAC2 endowed rice with premature senility, which indicated OsNAC2 might play a role in the pathway of leaf senescence (Chen et al, 2015). However, the underlying molecular mechanisms of OsNAC2 regulating leaf senescence were poorly understood.…”

OsbZIP48, a HY5 Transcription Factor Ortholog, Exerts Pleiotropic Effects in Light-Regulated Development

“…The list of genes involved in controlling rice plant height and their expression in overexpression transgenics is provided in Table I. The expression of some of them, including OsNAC2, OsGDD1, OsPIL1, and OsEATB, was checked Qi et al, 2011;Todaka et al, 2012;Chen et al, 2015). The expression of OsNAC2 was high, but OsPIL1, OsGDD1, and OsEATB were down-regulated in these transgenics (Fig.…”