HEAT SHOCK PROTEIN 90.6 interacts with carbon and nitrogen metabolism components during seed development

Abstract

Carbon and nitrogen are the two main nutrients in maize (Zea mays L.) kernels, and kernel filling and metabolism determine seed formation and germination. However, the molecular mechanisms underlying the relationship between kernel filling and corresponding carbon and nitrogen metabolism remain largely unknown. Here, we found that HEAT SHOCK PROTEIN 90.6 (HSP90.6) is involved in both seed filling and the metabolism processes of carbon and nitrogen. A single-amino acid mutation within the HATPase_c domain of HSP90.6 led to small kernels. Transcriptome profiling showed that the expression of amino acid biosynthesis- and carbon metabolism-related genes was significantly downregulated in the hsp90.6 mutant. Further molecular evidence showed strong interactions between HSP90.6 and the 26S proteasome subunits REGULATORY PARTICLE NON-ATPASE6 (RPN6) and PROTEASOME BETA SUBUNITD2 (PBD2). The mutation of hsp90.6 significantly reduced the activity of the 26S proteasome, resulting in the accumulation of ubiquitinated proteins and defects in nitrogen recycling. Moreover, we verified that HSP90.6 is involved in carbon metabolism through interacting with the 14-3-3 protein GENERAL REGULATORY FACTOR14-4 (GF14-4). Collectively, our findings revealed that HSP90.6 is involved in seed filling and development by interacting with the components controlling carbon and nitrogen metabolism.

CPK1‐HSP90 phosphorylation and effector XopC2–HSP90 interaction underpin the antagonism during cassava defense‐pathogen infection

“…As one conserved molecular chaperone, HEAT-SHOCK PRO-TEIN 90 kDa (HSP90) is essential for plant development and stress responses through integrating client-mediated molecular modules (Samakovli et al, 2020(Samakovli et al, , 2021Thirumalaikumar et al, 2021;Xu et al, 2023). In Arabidopsis, HSP90 interacts with some crucial phytohormone components such as auxin receptor TRANSPORT INHIBITOR RESPONSE 1 (TIR1; Wang et al, 2016), highlighting the crucial role of HSP90 in fine-tuning phytophormone signaling transduction (Samakovli et al, 2020).…”

Genetic variation in ZmKW1 contributes to kernel weight and size in dent corn and popcorn

“…qHKW3 harbours the gene Zm00001d044081 , which encodes a homeobox‐leucine zipper protein (ATHB‐4), affecting kernel weight and size by regulating kernel filling (Sun et al ., 2022a). In addition, several genes controlling maize grain development have been identified, and their biological roles, such as ZmGRAS11 (Ji et al ., 2022), opaque2 (Zhang et al ., 2016), Smk11 (Ren et al ., 2023), crk2 (Zhou et al ., 2023), dek (Garcia et al ., 2017), HSP90.6 (Xu et al ., 2023), and TaDA1 (Liu et al ., 2020), have been revealed. Hence, it is crucial to uncover the genetic basis of major QTLs or candidate genes controlling kernel size and weight in maize and gain insights into the molecular mechanisms underlying yield‐related traits.…”