Journal of Integrative Plant Biology最新文献

The assembly of functional biological materials requires precise control over the synthesis and deposition of their constituent polymers. In plants, specialized cells gain exceptional strength from their secondary cell walls (SCWs), though the mechanisms ensuring the coordinated production of SCW components remain poorly understood. Using cotton fiber as a model for massive cellulose deposition, we uncover a multi-tiered transcriptional cascade involving the R2R3-MYB transcription factor GhMYB44. We show that GhMYB44 functions as a positive regulator that directly activates the pivotal NAC factor, GhFSN43, which in turn commands key cellulose synthesis genes, establishing a complete regulatory module from an upstream MYB to downstream structural genes. Crucially, we reveal that this entire pathway is potentiated at two distinct nodes through protein-protein interactions: an upstream GhMYB44-GhREV5 complex enhances the initial signal, while a downstream GhFSN43-GhFSN1 complex functions cooperatively to strengthen downstream transcriptional activation. Our findings suggest that GhMYB44 participates in a multi-tiered regulatory module where transcriptional output is enhanced by layered synergistic protein-protein interactions. This work clarifies a key regulatory pathway controlling SCW biosynthesis and offers novel targets for improving cotton fiber quality.

Wild perennial sister species Medicago archiducis-nicolai (rhizomatous/alpine) and M. ruthenica (non-rhizomatous/xeric) constitute vital genetic resources for forage improvement. To decode the genomic basis of their contrasting trait and habitat adaptation, we generated chromosome-scale genome assemblies, resequenced 128 individuals, profiled transcriptomes under cold/heat stress, and functionally validated causal alleles. We demonstrate that structural variations (SVs)-particularly gene duplications-are primary drivers of rhizome formation and alpine/xeric adaptation. Further, pervasive presence-absence SVs (PAVs) in noncoding regulatory regions underpin divergent allele-specific expression governing rhizome development and stress responses. Crucially, these regulatory PAVs induce contrasting expression patterns during trait development and stress adaptation. Our findings reveal a dual mechanism whereby coding and regulatory SVs convergently orchestrate phenotypic innovation and ecological specialization in sister species, offering valuable genomic resources for legume evolution studies and alfalfa breeding.

Rice is one of the most important food crops in the world and it is prone to attack by many diseases, such as the rice blast, sheath blight, bacterial leaf blight, and so on. These diseases represent the main constraints in rice production, threatening food security and safety. Here, new control strategies against these major rice diseases have been developed either by heterologous expression of a pathogen effector UvScd1 from false smut fungus Ustilaginoidea virens or by spraying the engineered biocontrol agent Bacillus subtilis secreting the effector UvScd1. Compared to the wild-type rice Zhonghua11 (ZH11), the rice line heterologously expressing UvScd1 showed lesion mimics and upregulated the expression of defense-related genes in leaves, including genes related to the JA and SA signaling pathways. As expected, the transgenic rice line showed broad-spectrum resistance to hemibiotrophic fungus Magnaporthe oryzae, necrotrophic fungus Rhizoctonia solani, and bacterium Xanthomonas oryzae pv. oryzae (Xoo), while there was no effect on yield-related agronomic traits compared with ZH11, suggesting that the effector UvScd1 confers both plant resistance via induction of ROS and defense-related genes, and maintains the balance between plant resistance and yield. In field experiments, comparable control efficiencies against these major rice diseases were achieved by spraying B. subtilis engineered to secrete UvScd1 and corresponding chemical pesticides, underscoring that use of biocontrol agents to secrete certain pathogen effector proteins is an effective strategy for the management of plant diseases. It is noteworthy that the application of B. subtilis engineered to secrete UvScd1 also achieved effective control for a variety of crop diseases, suggesting its excellent potential for use in practice.

Leaf morphology varies substantially across plant species. In soybeans, the regulation of compound leaf development remains poorly characterized, despite its critical role in plant architecture. Some soybean cultivars have compound leaves with up to five leaflets, while most are trifoliolate. Using genetic mapping, we identified a gene behind the leaflet number variation as LF1, an AP2/ERF transcription factor. High expression levels of LF1 were further observed in leaf primordium initiation sites, leaf primordia, and leaflet initiation domains. Transgenic overexpression of LF1 increased leaflet number. Further investigation revealed that LF1 regulates leaflet development through negative autoregulation via GCC-box cis-element binding. In addition to the role of LF1, the CRISPR-edited mutant of TEOSINTE-BRANCHED1/CYCLOIDEA/PCF3 (GmTCP3) displayed serrated blade margins in juvenile leaves and increased compound leaflet numbers. Protein interaction assays confirmed LF1 binding affinity for GmTCP3. Furthermore, we demonstrate that LF1 induces the expression of GmLFY, a key regulator of leaflet development. Altogether, our findings establish LF1 as a central regulator of soybean leaflet morphogenesis and reveal its mechanistic interactions with GmTCP3 and LEAFY (GmLFY), offering novel mechanistic insights into the genetic control of compound leaf development.

Low light is one of the main environmental factors influencing the content of soluble sugar in oriental melon fruit under protected cultivation. As a supplementary light source, light-emitting diodes have been widely used to improve fruit quality. However, the regulatory mechanism of light quality on oriental melon fruit quality remains unclear. Here, the high sucrose melon fruit was treated with different light qualities during the development stage in a greenhouse, and the results showed that red light significantly increased the sucrose content and upregulated the expression of sucrose transport and metabolism-related genes (CmSUT2, CmSWEET10, and CmSUS2) in melon fruit. In addition, CmWRKY28 was found using a yeast single-hybrid cDNA library, which responded to red light treatment and could bind to the promoters of CmSUT2, CmSWEET10, and CmSUS2 to activate their expression. Moreover, CmHY5 acted as a positive regulator of sucrose accumulation by directly binding to CmSUT2 and CmWRKY28 promoters. CmHY5 also interacted with CmWRKY28 at the protein level to participate in the regulation of sucrose accumulation. Taken together, these findings revealed that red light induced CmHY5 and CmWRKY28 to positively regulate the expression of target genes, promoting the accumulation of more sucrose in melon fruit. This study provided new insights into alleviating the effects of low-light conditions on melon fruit quality.

Strigolactones, as signaling molecules and plant hormones, play essential roles in rhizosphere communication and plant growth and development. Strigolactones are structurally highly diversified, suggesting their biosynthesis is highly complex, with a range of different enzymes involved. Over the past decades, significant progress has been achieved in elucidating strigolactone biosynthesis in different plant species, which highlights particularly the importance of the cytochrome P450 family. Here, we give an overview of methodologies used for the discovery and functional characterization of the cytochrome P450s in strigolactone biosynthesis, classify and summarize these members discovered so far, review their biological importance, and discuss techniques in strigolactone biosynthesis research. Finally, we provide an outlook on some unsolved issues in strigolactone biology and discuss potential practical applications in agriculture.

The inhibited growth of primary roots (PRs) is a typical adaptive response of Arabidopsis to low phosphate (LP) stress. The role of auxin and its relationship with iron (Fe) in this process, however, remains unclear. In this study, we demonstrated that auxin acts as a positive regulator. A high concentration of auxin at the tips of PRs stimulates vigorous PR growth in both LP-arf7 arf19 and LP-yucca mutants. The application of a low dose of exogenous auxin can partially mitigate LP-induced PR growth inhibition. Enhanced auxin signaling, achieved through overexpression of ARF7 or ARF19, also promotes PR growth in LP-transgenic plants. Conversely, LP stress negatively regulates the polar transport of auxin, leading to reduced PIN activity at PRs. Mutations of PINs and application of NPA, therefore, exacerbate the impact of LP stress on PR growth. Consistently, PIN activity remains stable in the PRs of LP-arf7 arf19 mutants, and mutation of PINs normalizes the inhibited growth of these mutants. Furthermore, a correlation is observed between decreased auxin activity and increased Fe at LP-PRs. Fe accumulation triggers a burst of reactive oxygen species (ROS), which inhibits polar auxin transport and distribution at the tips of PRs. Changes in Fe and ROS levels influence auxin activity at LP-PRs, while auxin conversely affects Fe accumulation at these sites. Consequently, Fe levels are low at the PRs of LP-arf7 arf19 mutants, LP-yucca mutants, and auxin-treated LP-WT plants. Conversely, they are high in PRs of LP-pin2 mutant and NPA-treated LP-WT plants. In conclusion, accumulated Fe triggers a burst of ROS, disrupting auxin transport by decreasing PIN activity at LP-PRs. This disruption subsequently inhibits cell division and overall PR growth.

Lignified stone cells are a unique feature of pear fruit, significantly affecting fruit texture. Even though some research efforts have already been made, the stone cell formation mechanism is complex, with many aspects yet to be elucidated. Here, through a genome-wide association analysis of stone cell traits, we identified PbrMADS1, a member of the SEPALLATA3 (SEP3) subfamily, as a candidate gene specifically expressed in stone cells during early fruit development. Functional studies confirmed that PbrMADS1 promotes stone cell formation; however, it does not directly activate lignin-related genes. Instead, PbrMADS1 interacts with PbrMYB169, enhancing PbrMYB169's binding to AC elements and amplifying downstream gene activation. Notably, homologous MADS1 and MYB169 proteins from closely related species such as apple and loquat do not form a similar complex. Sequence analysis revealed that the protein sequence of PbrMADS1 contains methionine (M) at the 63^rd amino acid position, while apple and loquat homologs carry threonine (T) at the same site. Substituting M with T (PbrMADS1^M63T) weakened its interaction with PbrMYB169 and impaired its function in regulating stone cell formation. This study offers new insights into MADS gene-mediated stone cell formation and highlights functional divergence within the SEP3 subfamily among apple tribe species of the Rosaceae family.