The Tartary buckwheat bHLH gene ALCATRAZ contributes to silique dehiscence in Arabidopsis thaliana.

Tartary buckwheat is popular because of its rich nutrients. However, the difficulty in shelling restricts food production. The gene ALCATRAZ (AtALC) plays a key role in silique dehiscence in Arabidopsis thaliana. In this study, an atalc mutant was obtained by CRISPR/Cas9, and a FtALC gene homologous to AtALC was complemented into the atalc mutant to verify its function. Phenotypic observations showed that three atalc mutant lines did not dehiscence, while ComFtALC lines recovered the dehiscence phenotype. The contents of lignin, cellulose, hemicellulose, and pectin in the siliques of all the atalc mutant lines were significantly higher than those in the wild-type and ComFtALC lines. Moreover, FtALC was found to regulate the expression of cell wall pathway genes. Finally, the interaction of FtALC with FtSHP and FtIND was verified by yeast two-hybrid, bimolecular fluorescent complimentary (BIFC) and firefly luciferase completion imaging assays (LCIs). Our findings enrich the silique regulatory network and lay the foundation for the cultivation of easily shelled tartary buckwheat varieties.

CqZF-HD14 enhances drought tolerance in quinoa seedlings through interaction with CqHIPP34 and CqNAC79.

Drought stress is a key agricultural problem that restricts plant development and crop yield. Research on quinoa (Chenopodium quinoa), a nutrient-rich crop with strong stress resistance, has been limited in terms of the molecular regulation of its adaptation to drought stress. This study identified the zinc finger-homeodomain (ZF-HD) family in quinoa and a drought-responsive Chenopodium quinoa ZF-HD14 (CqZF-HD14) through expression profiles. Transient overexpression of CqZF-HD14 promotes photosynthetic pigment accumulation under drought stress, strengthens the antioxidant system, and in turn enhances drought tolerance. Comprehensive genome-wide family analysis and expression profiling identified CqNAC79 and CqHIPP34 regulated by CqZF-HD14, and their interactions were further determined by bimolecular fluorescence complementation (BIFC). Moreover, physiological and biochemical analyses and transient overexpression also revealed that CqNAC79 and CqHIPP34 resist drought by promoting the accumulation of photosynthetic pigments and maintaining antioxidant capacity under drought stress. The synergistic effect of CqZF-HD14 with CqNAC79 or CqHIPP34 further enhanced the drought tolerance of quinoa seedlings. Taken together, the results indicate that CqZF-HD14, CqNAC79 and CqHIPP34 may be important contributors to the drought tolerance regulatory network in quinoa, and these findings add new members to the drought tolerance gene pool.

Involvement of Auxin-Mediated CqEXPA50 Contributes to Salt Tolerance in Quinoa (Chenopodium quinoa) by Interaction with Auxin Pathway Genes.

Soil salinization is a global problem that limits crop yields and threatens agricultural development. Auxin-induced expansins contribute to plant salt tolerance through cell wall loosening. However, how auxins and expansins contribute to the adaptation of the halophyte quinoa (Chenopodium quinoa) to salt stress has not yet been reported. Here, auxin was found to contribute to the salt tolerance of quinoa by promoting the accumulation of photosynthetic pigments under salt stress, maintaining enzymatic and nonenzymatic antioxidant systems and scavenging excess reactive oxygen species (ROS). The Chenopodium quinoa expansin (Cqexpansin) family and the auxin pathway gene family (Chenopodium quinoa auxin response factor (CqARF), Chenopodium quinoa auxin/indoleacetic acid (CqAux/IAA), Chenopodium quinoa Gretchen Hagen 3 (CqGH3) and Chenopodium quinoa small auxin upregulated RNA (CqSAUR)) were identified from the quinoa genome. Combined expression profiling identified Chenopodium quinoa α-expansin 50 (CqEXPA50) as being involved in auxin-mediated salt tolerance. CqEXPA50 enhanced salt tolerance in quinoa seedlings was revealed by transient overexpression and physiological and biochemical analyses. Furthermore, the auxin pathway and salt stress-related genes regulated by CqEXPA50 were identified. The interaction of CqEXPA50 with these proteins was demonstrated by bimolecular fluorescence complementation (BIFC). The proteins that interact with CqEXPA50 were also found to improve salt tolerance. In conclusion, this study identified some genes potentially involved in the salt tolerance regulatory network of quinoa, providing new insights into salt tolerance.

Malate-mediated CqMADS68 enhances aluminum tolerance in quinoa seedlings through interaction with CqSTOP6, CqALMT6 and CqWRKY88.

Aluminum (Al) stress in acidic soils has severe negative effects on crop productivity. In this study, the alleviating effect and related mechanism of malate on Al stress in quinoa (Chenopodium quinoa) seedlings were investigated. The findings indicated that malate alleviated the growth inhibition of quinoa seedlings under Al stress, maintained the enzymatic and nonenzymatic antioxidant systems, and aided resistance to the damage caused by excessive reactive oxygen species (ROS). Under Al stress, malate significantly increased the contents of chlorophyll and carotenoids in quinoa shoots by 103.8% and 240.7%, and significantly increased the ratios of glutathione (GSH)/oxidized glutathione (GSSG), and ascorbate (AsA)/dehydroascorbate (DHA) in roots by 59.9% and 699.2%, respectively. However, malate significantly decreased the superoxide radical (O2•-), hydrogen peroxide (H2O2), malondialdehyde (MDA) and Al contents in quinoa roots under Al stress by 32.7%, 60.9%, 63.1% and 49%, respectively. Moreover, the CqMADS family and the Al stress-responsive gene families (CqSTOP, CqALMT, and CqWRKY) were identified from the quinoa genome. Comprehensive expression profiling identified CqMADS68 as being involved in malate-mediated Al resistance. Transient overexpression of CqMADS68 increased Al tolerance in quinoa seedlings. More importantly, we found that CqMADS68 regulated the expression of CqSTOP6, CqALMT6 and CqWRKY88 and further demonstrated the interaction of CqMADS68 with CqSTOP6, CqALMT6 and CqWRKY88 by bimolecular fluorescence complementation (BIFC) experiments. Moreover, transient overexpression and physiological and biochemical analyses demonstrated that CqSTOP6, CqALMT6 and CqWRKY88 could also improve Al tolerance by maintaining the antioxidant capacity of quinoa seedlings. Taken together, these findings reveal that CqMADS68, CqSTOP6, CqALMT6 and CqWRKY88 may be important contributors to the Al tolerance regulatory network in quinoa, providing new insights into Al stress resistance.