PUB30‐mediated downregulation of the HB24‐SWEET11 module is involved in root growth inhibition under salt stress by attenuating sucrose supply in Arabidopsis

Abstract

Summary One of the strategies that plants adopt to cope with an unfavorable environment is to sacrifice their growth for tolerance. Although moderate salt stress can induce root growth inhibition, the molecular mechanisms regulating this process have yet to be elucidated. Here, we found that overexpression of a zinc finger‐homeodomain family transcription factor, HOMEOBOX PROTEIN 24 (HB24), led to longer primary roots than in the wild‐type in the presence of 125 mM NaCl, whereas this phenotype was reversed for the hb24 loss‐of‐function mutant, indicating a negative impact of HB24 on salt‐induced root growth inhibition. We then found that salt stress triggered the degradation of HB24 via the ubiquitin–proteasome pathway, as mediated by a plant U‐box type E3 ubiquitin ligase 30 (PUB30) that directly targets HB24. We verified that HB24 is able to directly bind to the promoters of Sugars Will Eventually be Exported Transporter 11/12 (SWEET11/12) to regulate their expression in roots. Through genetic and biochemical assays, we further demonstrated that the HB24‐SWEET11 module plays a negative role in salt‐induced root growth inhibition. Therefore, we propose that under salt stress, PUB30 mediates HB24′s degradation, thereby downregulating the expression of SWEET11, resulting in reduced sucrose supply and root growth inhibition.

Zinc Finger-Homeodomain Transcriptional Factors (ZHDs) in Cucumber (Cucumis sativus L.): Identification, Evolution, Expression Profiles, and Function under Abiotic Stresses

“…CsZHD1 and CsZHD2, members of the same clade, exhibited high expression levels in the leaf and flower bud (Figure 5A,B), suggesting a conserved function of ZHD III members across different plant species. Moreover, CsZHD6 and CsZHD7 displayed high expression in the root (Figure 5E,F), diverging from the other CsZHD genes and aligning with the homologous AtZHD5, known for its role in promoting root hair elongation [22,23]. TaZFHD1 has been reported to exhibit a preferential expression pattern at the 'half, completely emerged' and 'half anthesis' stages during spike development, indicating its potential involvement in wheat anthesis and pollination [40].…”

“…The ZHD gene family was comprehensively identified in various plants, with instances such as 17 genes in Arabidopsis [10], 15 genes in rice [11], 37 genes in wheat [12], 20 genes in Tartary buckwheat [13], 31 genes in Chinese cabbage [14], 22 genes in tomato [15], 11 genes in chilli [16], and 37 genes in cotton [17]. Several ZHDs have been characterized for their crucial roles in diverse developmental processes, such as leaf development [11,18,19], seed longevity [20], hypocotyl growth [21], root hair elongation [22,23], and flower development [24]. In addition, they play a significant role in plant tolerance to various abiotic stresses, including drought [25,26], salt [27], dehydration, and heat [28], as well as biotic stresses like pathogen attacks [29].…”

Screening and Identification of Saline-Tolerant Germplasm in Melon

“…It can also disrupt the balance of the antioxidant system in plants, leading to increased membrane lipid peroxidation [19]. To adapt to soil salinization, plants have evolved various strategies [20], including antioxidant systems and osmotic regulation [21]. Previous research has highlighted the importance of maintaining a high cytosolic K + /Na + ratio as a key characteristic of salt-tolerant plants, often suggested as a valuable screening criterion for plant breeders [22].…”