Dwarf Stature Research Articles

A gain-of-function mutation in BnaIAA13 disrupts vascular tissue and lateral root development in Brassica napus.

Rapeseed (Brassica napus) is an important oilseed crop worldwide. Plant vascular tissues are responsible for long-distance transport of water and nutrients and for providing mechanical support. The lateral roots absorb water and nutrients. The genetic basis of vascular tissue and lateral root development in rapeseed remains unknown. This study characterized an ethyl methanesulfonate-mutagenized rapeseed mutant, T16, which showed dwarf stature, reduced lateral roots, and leaf wilting. SEM observations showed that the internode cells were shortened. Observations of tissue sections revealed defects in vascular bundle development in the stems and petioles. Genetic analysis revealed that the phenotypes of T16 were controlled by a single semi-dominant nuclear gene. Map-based cloning and genetic complementarity identified BnaA03.IAA13 as the functional gene; a G-to-A mutation in the second exon changed glycine at position 79 to glutamic acid, disrupting the conserved degron motif VGWPP. Transcriptome analysis in roots and stems showed that auxin and cytokinin signaling pathways were disordered in T16. Evolutionary analysis showed that AUXIN/INDOLE-3-ACETIC ACID is conserved during plant evolution. The heterozygote of T16 showed significantly reduced plant height while maintaining other agronomic traits. Our findings provide novel insights into the regulatory mechanisms of vascular tissue and lateral root development, and offer a new germplasm resource for rapeseed breeding.

Roles of microbiota in autoimmunity in Arabidopsis leaves

Over the past three decades, researchers have isolated plant mutants that show constitutively activated defence responses in the absence of pathogen infection. These mutants are called autoimmune mutants and are typically dwarf and/or bearing chlorotic/necrotic lesions. Here, from a genetic screen for Arabidopsis genes involved in maintaining a normal leaf microbiota, we identified TIP GROWTH DEFECTIVE 1 (TIP1), which encodes an S-acyltransferase, as a key player in guarding leaves against abnormal microbiota level and composition under high-humidity conditions. The tip1 mutant has several characteristic phenotypes of classical autoimmune mutants, including a dwarf stature, showing lesions, and having a high basal level of defence gene expression. Gnotobiotic experiments revealed that the autoimmune phenotypes of the tip1 mutant are largely dependent on the presence of microbiota as axenic tip1 plants have markedly reduced autoimmune phenotypes. We found that the microbiota dependency of autoimmune phenotypes is shared by several ‘lesion mimic’-type autoimmune mutants in Arabidopsis. It is worth noting that autoimmune phenotypes caused by mutations in two Nucleotide-Binding, Leucine-Rich Repeat (NLR) genes do not require the presence of microbiota and can even be partially alleviated by microbiota. Our results therefore suggest the existence of at least two classes of autoimmunity (microbiota-dependent versus microbiota-independent) in plants. The observed interplay between autoimmunity and microbiota in the lesion mimic class of autoimmunity is reminiscent of the interactions between autoimmunity and dysbiosis in the animal kingdom. These parallels highlight the intricate relationship between host immunity and microbial communities across various biological systems.

Telomere-to-telomere genome assembly of sorghum

“Cuohu Bazi” (CHBZ) is an ancient sorghum variety collected from the fields of China, known for its agronomic traits like dwarf stature, early maturation. In this study, we present the first telomere-to-telomere (T2T) and gap-free genome assembly of CHBZ using PacBio HiFi reads, Oxford Nanopore Technologies, and Hi-C data. The assembled genome comprises 724.85 Mb, effectively resolving all 3,913 gaps that were present in the previous sorghum BTx623 reference genome. Notably, the T2T assembly captures 10 centromeres and all 20 telomeres, providing strong support for their integrity. This assembly is of high quality in terms of contiguity (contig N50: 71.1 Mb), completeness (BUSCO score: 99.01%, k-mer completeness: 98.88%), and correctness (QV: 61.60). Repetitive sequences accounted for 70.41% of the genome and a total of 32,855 protein-coding genes have been annotated. Furthermore, 161 CHBZ-specific presence/absence variants genes have been identified when comparing to BTx623 genome. This study provides valuable insights for future research on sorghum genetics, genomics, and evolutionary history.

PpGATA21 Enhances the Expression of PpGA2ox7 to Regulate the Mechanism of Cerasus humilis Rootstock-Mediated Dwarf in Peach Trees.

Dwarfing rootstocks enhance planting density, lower tree height, and reduce both labor in peach production. Cerasus humilis is distinguished by its dwarf stature, rapid growth, and robust fruiting capabilities, presenting substantial potential for further development. In this study, Ruipan 4 was used as the scion and grafted onto Amygdalus persica and Cerasus humilis, respectively. The results indicate that compared to grafting combination R/M (Ruipan 4/Amygdalus persica), grafting combination R/O (Ruipan 4/Cerasus humilis) plants show a significant reduction in height and a significant increase in flower buds. RNA-seq indicates that genes related to gibberellin (GA) and auxin metabolism are involved in the dwarfing process of scions mediated by C. humilis. The expression levels of the GA metabolism-related gene PpGA2ox7 significantly increased in R/O and are strongly correlated with plant height, branch length, and internode length. Furthermore, GA levels were significantly reduced in R/O. The transcription factor PpGATA21 was identified through yeast one-hybrid screening of the PpGA2ox7 promoter. Yeast one-hybrid (Y1H) and dual-luciferase reporter (DLR) demonstrate that PpGATA21 can bind to the promoter of PpGA2ox7 and activate its expression. Overall, PpGATA21 activates the expression of the GA-related gene PpGA2ox7, resulting in reduced GA levels and consequent dwarfing of plants mediated by C. humilis. This study provides new insights into the mechanisms of C. humilis and offers a scientific foundation for the dwarfing and high-density cultivation of peach trees.

Identification and Transcriptome Analysis of a Novel Allelic Mutant of NAL1 in Rice.

Leaf morphology is a crucial aspect of plant architecture, yet the molecular mechanisms underlying leaf development remain incompletely understood. In this study, a narrow leaf mutant, m625, was identified in rice (Oryza sativa L.), exhibiting pleiotropic developmental defects. Pigment measurement revealed reduced levels of photochromic pigments in m625. Cytological analysis demonstrated that the m625 gene affected vascular patterns and cell division. Specifically, the narrowing of the leaf was attributed to a decrease in small vein number, shorter vein spacing, and an abnormal V-shaped arrangement of bulliform cells, while the thickening was caused by longer leaf veins, thicker mesophyll cells, and an increased number of parenchyma cell layers. The dwarf stature and thickened internode were primarily due to shortened internodes and an increase in cell layers, respectively. Positional cloning and complementation assays indicated that the m625 gene is a novel allele of NAL1. In the m625 mutant, a nucleotide deletion at position 1103 in the coding sequence of NAL1 led to premature termination of protein translation. Further RNA-Seq and qRT-PCR analyses revealed that the m625 gene significantly impacted regulatory pathways related to IAA and ABA signal transduction, photosynthesis, and lignin biosynthesis. Moreover, the m625 mutant displayed thinner sclerenchyma and cell walls in both the leaf and stem, particularly showing reduced lignified cell walls in the midrib of the leaf. In conclusion, our study suggests that NAL1, in addition to its known roles in IAA transport and leaf photosynthesis, may also participate in ABA signal transduction, as well as regulate secondary cell wall formation and sclerenchyma thickness through lignification.

Evaluation and characterization of TILLING-based putative mutant populations of papaya cv. Arka Prabhath

Manifestation of virus resistance, shelf-life with dwarf stature are important pre-requisites for successful cultivation of papaya in India as it facilitates improved production, productivity and reduced post-harvest loss. One of the methods to create variability is to use mutagens in selected cultivar of papaya. Accordingly, the TILLING-based mutant populations of papaya cv. Arka Prabhath were generated through irradiation of gamma rays ranging from 50 to 500 Gy dosage. In this experiment, the putative mutant populations were evaluated and characterized based on morphological, fruit quality and physiological parameters. Desirable traits such as early flowering, reduced plant height and bearing height, papaya ring spot virus tolerant plants and fruits with extended shelf life were observed in the mutant population. Early flowering and reduced plant height with wide variation was found at 50 Gy wherein the first flowering was on 57 days with 43 cm of plant height in contrast to 80 days in control plants with 79 cm of plant height. Reduced bearing height (40 cm) was observed in 100 Gy with a mean bearing height of 70.65 cm in comparison to control plants (72.97 cm), range being 55 to 115 cm. Further, based on morphological traits twenty-one lines were selected for physiological and fruit quality trait evaluation. Reduction in physiological loss in weight, ethylene evolution rate and respiration rate were observed in the mutant lines treated with 150 Gy dosage. The results advocate the efficacy of gamma induced mutation for developing dwarf cultivar with improved quality and shelf-life of fruits.

A low carbon balance triggers Microvine inflorescence abscission at high temperatures

IntroductionGlobal warming is a major threat to yield sustainability in most crops, including grapevine. Whether or not grapevine fruitfulness is impaired by an imbalance between carbon supply and demand caused by high temperatures was investigated in the present study.MethodsFive experiments were conducted on Microvine, a natural mutant of grapevine that is insensitive to gibberellins, presents with a dwarf stature, and has continuous flowering along the vegetative axes. The last property was used to infer temporal patterns of inflorescence development from their spatial distribution at harvest. Two sets of plants, characterized by low or high levels of initial shoot vigor, were grown under contrasting day and night temperatures: 22°C/12°C and 30°C/20°C.Results and discussionThe rate of leaf development of the main shoot was stable, regardless of the initial vigor and temperature treatment. In contrast, the warm temperatures delayed the timing of flowering for low-vigor plants or the onset of ripening for high-vigor plants. Fruitfulness was impaired by high temperatures as a result of the abscission of young inflorescences (before the flowering stage). From a careful spatiotemporal analysis of cluster abscission, we concluded that inflorescence drop under elevated temperatures was triggered by the increase in plant carbon demand due to the oldest clusters starting to unload sugars. Elevated temperatures may have also lowered the carbohydrate supply in the zone of inflorescence abscission due to the higher leaf respiration while all organ growth demand was maintained. Interestingly, inflorescence abscission occurred earlier when whole-plant vigor was low and was followed by a recovery period, in spite of a lower non-structural sugar status than in high-vigor plants. Taken together, our results suggest that inflorescence abscission is linked to the variations of the carbon pool induced by changes in temperature and not to its absolute value. Our study, therefore, provides new hypotheses about the impacts of warm temperatures on the regulation of temperature-induced reproductive failure in grapevine.

Induction and Characterization of Mutations Related to Dwarf Habit in Hardy Hibiscus (Muenchhusia section)

Hybrids between various species of Hibiscus in the Muenchhusia section are popular in commercial markets due to their colorful, floriferous blooms. However, many commercial cultivars are too vigorous for use in smaller garden spaces and often have only a few flowers in bloom. Stable, heritable mutants exhibiting dwarf stature and better branching architecture will be valuable to the commercial production of hardy Hibiscus. The goal of this project was to induce stable, heritable mutations using ethyl methanesulfonate that result in increased branching and a dwarf compact phenotype and introgress the compact phenotypes into lines of hardy Hibiscus to generate a series of diverse compact cultivars for use in commercial markets. Multiple mutations associated with dwarf, compact phenotypes were successfully induced. Hybridizations were made between M2 plants displaying a dwarf phenotype and hybrids developed through conventional breeding that do not possess the dwarf mutation in their background to develop diverse selections of dwarf plants. Inheritance patterns of the dwarf genes were determined through the segregation ratios of the dwarf phenotype in the F1 and F2 generations of these hybrids. Compared with wild-type progeny, dwarf progeny had shorter internode lengths and a greater number of primary branches.

Genetic analysis of agronomic traits of inter-subspecific cross populations of Tartary buckwheat

To provide a good basis for breeding new varieties, 2 different Tartary buckwheat (Fagopyrum tataricum Gaertn. 2x = 16) lines belonging to different subspecies with large differences in plant height were crossed. The progeny was analyzed for the genetic pattern of each agronomic trait and correlation analysis between traits. In terms of their coefficients of variation, the node numbers on the main stem and the weights per thousand kernels were small, while the number/weight of seeds per plant was large, indicating that the former character is more stable while the latter has greater potential for improvement. The average degrees of the dominance of plant height, number of main stem nodes, and number/weight of seeds per plant were greater than 1, indicating that these traits were mainly controlled by dominant effects. The heritability of the thousand kernel weight was greater than for the other traits, indicating that this trait is suitable for single plant selection in early generations. Correlation analysis of each agronomic trait revealed that plant height was significantly and positively correlated with all other traits in the F3 population, indicating the difficulty of selecting strains with both dwarf stature and high-yield traits. Nevertheless, 13 strains with dwarf stems and high yields were screened in the F5 population. Our study shows that the thousand kernel weight can be improved by single plant selection, while other traits need to be considered together to achieve optimal selection when endeavoring to breed dwarf, high-yield Tartary buckwheat.

Determination of mutagenic sensitivity and its manifestations on papaya (Carica papaya L.) cv. Arka Prabhath

Papaya is an important fruit crop of the family Caricaceae which needs the improvement in terms of virus resistance and shelf life with dwarf stature. Mutation breeding technique has been considered as an efficient tool adopted by plant breeders to create variability in papaya. The mutation frequency and population structure of the mutants directly depend upon the type of mutagen and the time of exposure. Irrespective of the used mutagens, the ultimate induced mutations are random and therefore determination of mutagenic sensitivity is important pre-requisite. Based on this, investigation on the induction of mutation in papaya cv. Arka Prabhath was carried out with the objective of creating genetic variability through physical mutagen. In this study, papaya seeds were irradiated with five different dose of gamma rays ranging from 50 Gy to 500 Gy. The results revealed that gradual reduction in germination, survival of seedlings and delayed germination with increase in dosage of gamma rays. Based on probit analysis, LD50 (Lethal dose) was fixed at 186.24 Gy. Total seven types of chlorophyll mutants were observed as a result of mutation. Mutagenic efficiency and effectiveness were higher in a lower dose of gamma treatment (50 Gy).

Mutant IAA21 genes from Dendrocalamus sinicus Chia et J. L. Sun inhibit stem and root growth in transgenic tobacco by interacting with ARF5

Woody bamboos are important resource of industrial fibres. Auxin signaling plays a key role in multiple plant developmental processes, as yet the role of auxin/indole acetic acid (Aux/IAA) in culm development of woody bamboos has not been previously characterized. Dendrocalamus sinicus Chia et J. L. Sun is the largest woody bamboo documented in the world. Here, we identified two alleles of DsIAA21 gene (sIAA21 and bIAA21) from the straight- and bent-culm variants of D. sinicus, respectively, and studied how the domains I, i, and II of DsIAA21 affect the gene transcriptional repression. The results showed that bIAA21 expression was rapidly induced by exogenous auxin in D. sinicus. In transgenic tobacco, sIAA21 and bIAA21 mutated in domains i, and II significantly regulated plant architecture and root development. Stem cross sections revealed that parenchyma cells were smaller in transgenic plants than that in wild type plants. Domain i mutation changed the leucine and proline at position 45 to proline and leucine (siaa21L45P and biaa21P45L) strongly repressed cell expansion and root elongation by reducing the gravitropic response. Substitution of isoleucine with valine in domain II of the full length DsIAA21 resulted in dwarf stature in transgenic tobacco plants. Furthermore, the DsIAA21 interacted with auxin response factor 5 (ARF5) in transgenic tobacco plants, suggesting that DsIAA21 might inhibit stem and root elongation via interacting with ARF5. Taken together, our data indicated that DsIAA21 was a negative regulator of plant development and suggested that amino acid differences in domain i of sIAA21 versus bIAA21 affected their response to auxin, and might play a key role in the formation of the bent culm variant in D. sinicus. Our results not only shed a light on the morphogenetic mechanism in D. sinicus, but also provided new insights into versatile function of Aux/IAAs in plants.

Genome-wide alternative polyadenylation dynamics underlying plant growth retardant-induced dwarfing of pomegranate.

Dwarfed stature is a desired agronomic trait for pomegranate (Punica granatum L.), with its advantages such as lower cost and increased yield. A comprehensive understanding of regulatory mechanisms underlying the growth repression would provide a genetic foundation to molecular-assisted dwarfing cultivation of pomegranate. Our previous study induced dwarfed pomegranate seedlings via exogenous application of plant growth retardants (PGRs) and highlighted the important roles of differential expression of plant growth-related genes in eliciting the dwarfed phenotype of pomegranate. Alternative polyadenylation (APA) is an important post-transcriptional mechanism and has been demonstrated to act as a key regulator in plant growth and development. However, no attention has been paid to the role of APA in PGR-induced dwarfing in pomegranate. In this study, we characterized and compared APA-mediated regulation events underlying PGR-induced treatments and normal growth condition. Genome-wide alterations in the usage of poly(A) sites were elicited by PGR treatments, and these changes were involved in modulating the growth and development of pomegranate seedlings. Importantly, ample specificities were observed in APA dynamics among the different PGR treatments, which mirrors their distinct nature. Despite the asynchrony between APA events and differential gene expression, APA was found to regulate transcriptome via influencing microRNA (miRNA)-mediated mRNA cleavage or translation inhibition. A global preference for lengthening of 3' untranslated regions (3' UTRs) was observed under PGR treatments, which was likely to host more miRNA target sites in 3' UTRs and thus suppress the expression of the corresponding genes, especially those associated with developmental growth, lateral root branching, and maintenance of shoot apical meristem. Together, these results highlighted the key role of APA-mediated regulations in fine-tuning the PGR-induced dwarfed stature of pomegranate, which provides new insights into the genetic basis underlying the growth and development of pomegranate.

Screening of castor germplasm for wilt reaction and morpho-molecular characterization of resistant genotypes

Castor (Ricinus communis L.) is an important industrial versatile non-edible oilseed C3 crop belongs to spurge family. Its oil has exceptional properties which provides an industrial importance to this crop. The present investigation was aimed to evaluate the genotypes of castor for Fusarium wilt reaction in pot followed by characterization of resistant genotypes for yield related traits in field and inter-genotype genetic diversity at DNA level. The percent disease incidence (PDI) among 50 genotypes ranged from 0 to 100%. A total of 36 genotypes were found wilt resistant (28 highly resistant and 8 resistant). ANOVA revealed that the genotypes MSS was significant for each trait studied, indicating the existence of plentiful variability in the experimental material. The morphological characterization showed that DCS-109 (73.30 cm) had a dwarf stature The genotype RG-1954 was superior for oil content (50.29%) with moderate for shelling out (67.63). RG-1673 was outstanding for seed boldness as 100 seed weight for this genotype was maximum (38.98 gm). JI-403 had maximum seed yield per plant (SYPP; 354.88 gm). SYPP positively associated with all traits except oil and seed length:breadth ratio. The path analysis revealed that the direct effects of NPR (0.549), TLFP (0.916), and CPP on SYPP are quite significant. A total of 38 alleles from 18 SSR markers were amplified in 36 genotypes. The NJ tree could divide 36 genotypes into three main clusters. AMOVA revealed 15% and 85% variance among and within subpopulations, respectively. Both morphological and SSR data demonstrated to be effective tools for discerning inter-genotypes diversity and categorizing high-yielding and disesae-tolerant castor genotypes lines.

Genetic diversity of ayeyarmin mutant rice population revealed by quantitative traits

One of the most important aspects of selecting genotypes with desirable characteristics for a successful breeding program is knowledge of the nature and magnitude of genetic variability. The goal of this study was to estimate the level of genetic divergence among mutant rice genotypes. During the 2020 dry season, a field experiment was carried out using 550 mutant lines with parent Ayeyarmin. The experiment was carried out using a simple CRD design. Six divergent groups were discovered by cluster analysis. Cluster I had the highest cluster mean for grain yield per plant, and the majority of the plants in these clusters resembled the parent Ayeyarmin. Cluster V, which had the fewest mutant lines (9), exhibited dwarf stature, short growth duration, fewer effective tillers per hill, and moderate yielding varieties. Cluster VI, which contained 11 mutant lines, had the most effective tillers per hill and the longest panicle length, both of which were appropriate for yield improvement. Cluster V had the greatest intra-cluster distance (5.77). Cluster V and IV had the greatest inter-cluster distance, followed by Cluster III and V, Cluster II and V, Cluster I and V, and the smallest between Cluster I and IV. Hybridization of Cluster I with V, Cluster V and VI could result in genotypes with desirable characteristics such as dwarf stature, short growth duration, and high yielding rice. The first three eigenvalues were found to have 62% variation using principal component analysis (PCA). Because of the high genetic variability in this mutant rice population, selection could be used to obtain desirable genotypes.

Linum usitatissimum FUSCA3–1 regulates plant architecture and seed storage reserve accumulation in Arabidopsis thaliana

Flax ( Linum usitatissimum L.) as a self-pollinated annual diploid crop is grown worldwide primarily for its seed storage reserves of oil and storage proteins. The B3 domain transcription factor AtFUSCA3 (AtFUS3) has been identified as a master regulator of seed storage reserve accumulation in Arabidopsis thaliana . However, the function of LuFUS3 from L. usitatissimum has not yet been assessed. Here, we found that there were two LuFUS3 homologs, LuFUS3–1 and LuFUS3–2, in the L. usitatissimum genome. The subcellular localization and yeast transcriptional activation assays indicated that LuFUS3–1 functions as a transcription factor. Heterogeneous expression of LuFUS3–1 in the A. thaliana wild type background changed the plant architecture, including moderately dwarf stature, wrinkled leaves, increased branch number, altered floral morphology, and shorter and wider siliques, which was at least partially caused by the significantly decreased level of endogenous gibberellins. On the other hand, we demonstrated that LuFUS3–1 enhances the accumulation of seed storage reserves inclusive of oil and storage proteins in A. thaliana seeds. Consistently, LuFUS3–1 promotes the expression of many genes involved in the biosynthesis of seed oil and storage proteins during seed development. These findings provide new insights into the FUS3 function in plant architecture and seed storage reserve accumulation, and also represent a promising target for genetic modification of L. usitatissimum . • LuFUS3-1 functions as a B3 domain transcription factor. • LuFUS3-1 regulates plant architecture at least dependent on gibberellin biosynthesis. • LuFUS3-1 promotes the accumulation of seed oil and storage proteins. • LuFUS3 boosts the expression of genes involved in seed oil and storage protein biosynthesis.

Rice CO 53: A high yielding drought tolerant rice variety for drought prone districts of Tamil Nadu

Early duration drought tolerant rice culture CB 06803, a derivative of the cross PMK (R ) 3 x Norungan was released as Rice CO 53 during the year 2020 as an alternate variety for Anna(R)4, with 115 -120 days duration. It possesses desirable features like high yield, drought tolerance and better physiological efficiency. This culture with semi dwarf stature has efficient tillering capacity, long droopy panicles with a highly acceptable plant characters and is a replacement for the rice variety Anna (R) 4 due to its grain yield and pest and disease resistance. In the overall yield analysis, the culture CB06803 recorded an overall mean grain yield of 3718 kg/ha which was 12.19 per cent increase over TKM (R) 12 and 14.08 per cent over Anna (R) 4 under dry condition. Under semi dry condition, it recorded 3866 kg/ha with 18.40 per cent increase over TKM (R) 12 and 8.67 per cent over Anna (R) 4. It is moderately resistant to WBPH, leaf blast, neck blast, sheath rot, brown spot and RTD under artificial condition. It has white short bold rice with high milling percentage (69.6), head rice recovery (59.6%) and suitable for idly making. The culture, CB 06803 had better  agronomic efficiency than TKM (R)12 and Anna (R) 4 by recording more number of productive tillers per plant and grain yield under control and drought. The culture CB 06803 had better physiological efficiency under drought than TKM (R) 12 and Anna (R) 4  having higher RWC, total chlorophyll content, chlorophyll stability index, photosynthetic rate, stomatal conductance and photo chemical efficiency. The culture had higher proline content than TKM (R) 12 and was on par with Anna (R) 4. It had higher catalase activity than Anna (R) 4. CB 06803 had better physiological efficiency under drought by showing partial closure of stomata as that of Sahbagidhan. CO 53 with higher grain yield under drought, disease resistance and short bold grains and suitable for cultivation in drought prone districts of Tamil Nadu as direct seeded rainfed or semi dry rice ecosystem. Keywords: Rice CO 53, bold grain rice, short duration, drought tolerance

Requirement and functional redundancy of two large ribonucleotide reductase subunit genes for cell cycle, chloroplast biogenesis and photosynthesis in tomato.

Ribonucleotide reductase (RNR), functioning in the de novo synthesis of deoxyribonucleoside triphosphates (dNTPs), is crucial for DNA replication and cell cycle progression. In most plants, the large subunits of RNR have more than one homologous gene. However, the different functions of these homologous genes in plant development remain unknown. In this study, we obtained the mutants of two large subunits of RNR in tomato and studied their functions. The mutant ylc1 was obtained by ethyl methyl sulfonate (EMS) treatment. Through map-based cloning, complementation and knock-out experiments, it was confirmed that YLC1 encodes a large subunit of RNR (SlRNRL1). The expression level of the genes related to cell cycle progression, chloroplast biogenesis and photosynthesis was assessed by RNA-sequencing. In addition, we knocked out SlRNRL2 (a SlRNRL1 homologue) using CRISPR-Cas9 technology in the tomato genome, and we down-regulated SlRNRL2 expression in the genetic background of slrnrl1-1 using a tobacco rattle virus-induced gene silencing (VIGS) system. The mutant slrnrl1 exhibited dwarf stature, chlorotic young leaves and smaller fruits. Physiological and transcriptomic analyses indicated that SlRNRL1 plays a crucial role in the regulation of cell cycle progression, chloroplast biogenesis and photosynthesis in tomato. The slrnrl2 mutant did not exhibit any visible phenotype. SlRNRL2 has a redundant function with SlRNRL1, and the double mutant slrnrl1slrnrl2 is lethal. SlRNRL1 is essential for cell cycle progression, chloroplast biogenesis and photosynthesis. In addition, SlRNRL1 and SlRNRL2 possess redundant functions and at least one of these RNRLs is required for tomato survival, growth and development.

Reciprocity between a retrograde signal and a putative metalloprotease reconfigures plastidial metabolic and structural states.

Reconfiguration of the plastidial proteome in response to environmental cues is central to tailoring adaptive responses. To define the underlying mechanisms and consequences of these reconfigurations, we performed a suppressor screen, using a mutant (ceh1) accumulating high levels of a plastidial retrograde signaling metabolite, MEcPP. We isolated a revertant partially suppressing the dwarf stature and high salicylic acid of ceh1 and identified the mutation in a putative plastidial metalloprotease (VIR3). Biochemical analyses showed increased VIR3 levels in ceh1, accompanied by reduced abundance of VIR3-target enzymes, ascorbate peroxidase, and glyceraldehyde 3-phophate dehydrogenase B. These proteomic shifts elicited increased H2O2, salicylic acid, and MEcPP levels, as well as stromule formation. High light recapitulated VIR3-associated reconfiguration of plastidial metabolic and structural states. These results establish a link between a plastidial stress-inducible retrograde signaling metabolite and a putative metalloprotease and reveal how the reciprocity between the two components modulates plastidial metabolic and structural states, shaping adaptive responses.

Gasteria disticha var. marxii, a new dwarf variety from the Western Cape Province, South Africa

Gasteria disticha var. marxii is described as a new variety from the lower foothills of the Witteberg and Klein Swartberg near Laingsburg, Western Cape, South Africa. It differs from other varieties mainly by its dwarf stature, an adaptation to its harsh habitat.

Uncovering the Gene Regulatory Network of Maize Hybrid ZD309 under Heat Stress by Transcriptomic and Metabolomic Analysis.

Maize is an important cereal crop but is sensitive to heat stress, which significantly restricts its grain yield. To explore the molecular mechanism of maize heat tolerance, a heat-tolerant hybrid ZD309 and its parental lines (H39_1 and M189) were subjected to heat stress, followed by transcriptomic and metabolomic analyses. After six-day-heat treatment, the growth of ZD309 and its parental lines were suppressed, showing dwarf stature and rolled leaf compared with the control plants. ZD309 exhibited vigorous growth; however, M189 displayed superior heat tolerance. By transcriptomic and metabolomic analysis, hundreds to thousands of differentially expressed genes (DEGs) and metabolites (DEMs) were identified. Notably, the female parent H39 shares more DEGs and DEMs with the hybrid ZD309, indicating more genetic gain derived from the female instead of the male. A total of 299 heat shock genes detected among three genotypes were greatly aggregated in sugar transmembrane transporter activity, plasma membrane, photosynthesis, protein processing in the endoplasmic reticulum, cysteine, and methionine metabolism. A total of 150 heat-responsive metabolites detected among three genotypes were highly accumulated, including jasmonic acid, amino acids, sugar, flavonoids, coumarin, and organic acids. Integrating transcriptomic and metabolomic assays revealed that plant hormone signal transduction, cysteine, and methionine metabolism, and α-linolenic acid metabolism play crucial roles in heat tolerance in maize. Our research will be facilitated to identify essential heat tolerance genes in maize, thereby contributing to breeding heat resistance maize varieties.