ABSTRACT Grain weight and size are among the most important yield traits in sorghum. They exhibit positive and negative correlations with several other agronomic traits. They are highly heritable and therefore have significant scope for genetic improvement. However, these are complex traits and are difficult to dissect, and much of their current mechanistic understanding derives from rice and maize rather than from direct evidence in sorghum. Here, we review the current knowledge of genetic regulation of grain weight and size. We discuss the relative contribution of genetic factors to the determination of potential grain weight in sorghum. We provide a comprehensive update on molecular networks, genetic loci, causal genes, and candidate genes identified to date for the regulation of sorghum grain weight and size. We also describe the various floral, fertilization, and seed‐related factors that determine grain weight. Further, we discuss the roles of the rate and duration of grain filling in the determination of sorghum grain weight and size. Furthermore, we outline potential strategies for engineering sorghum varieties with improved grain weight and size without compromising the grain number. These strategies include precision breeding, analysis of allelic variation, and identification of desirable alleles from wild germplasm. We also discuss the applications of omics resources and genome editing in developing improved sorghum cultivars.
ABSTRACT Hypnum leptothallum (Müll. Hal.) Paris, a pioneer moss species thriving in karst rocky desertification areas, exhibits remarkable desiccation tolerance and holds promise for ecological restoration initiatives. Despite its potential, the species faces limitations due to its slow growth rate. This study contributes significantly to the understanding of H. leptothallum by systematically documenting the developmental process from spore germination to young gametophore formation and establishing an efficient in vitro propagation system for widespread cultivation. Sequential developmental stages were identified through detailed morphological analysis, encompassing spore germination, protonemal differentiation, and gametophore formation. The culture system was optimized through singlefactor experiments and response surface methodology (RSM). Initial screening indicated that 0.2 mg L −1 kinetin (KT) was the most effective plant growth regulator. Further RSM optimization determined that a medium composed of −1/2.67 Benecke + 0.2 mg L −1 KT at pH 5.6 produced optimal growth. This medium yielded a protonemal patch diameter of 1.12 ± 0.047 mm, gametophore height of 1.97 ± 0.107 mm, gametophore yield of 9.75 ± 0.855 numbers, coverage of 19.32% ± 0.295%, and biomass of 0.17 ± 0.003 g. By following this established protocol, a sufficient amount of protonema material is ensured to facilitate the rapid cultivation of H. leptothallum using fragmented protonema and additional nutrients. This method provides a practical means for the mass production of H. leptothallum crusts, potentially contributing significantly to the mitigation of rocky desertification in karst regions.
ABSTRACT Recurrent drought limits the productivity of perennial crops such as citrus, whose tolerance to water deficit largely depends on scion–rootstock interactions. Although physiological responses to recurrent drought are well documented, the epigenetic states associated with these responses remain poorly understood, limiting the use of epigenetic variation to improve drought resilience. Here, we investigated whole‐genome DNA methylation profiles and transcriptional responses in “Pera‐D6” sweet orange (LP) grafted onto two rootstocks with contrasting physiological strategies for coping with water deficit: “Rangpur” lime (RL), associated with dehydration avoidance through enhanced water acquisition, and “Sunki Maravilha” mandarin (SM), associated with tighter regulation of transpiration and physiological adjustments under stress. Grafted plants were exposed to three cycles of water deficit followed by rehydration. In the scion, we detected rootstock‐dependent methylation dynamics, with LP/RL exhibiting broader patterns of methylation change and LP/SM showing a more targeted response. In the LP/SM combination, drought‐associated differentially methylated regions were linked to genes involved in photosynthesis, stomatal regulation, and transcriptional processes. For several stress‐responsive genes, promoter methylation changes coincided with qualitative trends in gene expression; however, no significant methylation–expression correlations were detected after multiple‐testing correction. These findings indicate that recurrent drought is associated with rootstock‐dependent persistent DNA methylation patterns with potential functional relevance. Overall, the results highlight the importance of considering epigenetic variation in studies of drought response and suggest that rootstock selection may play a role in shaping regulatory responses to water deficit in citrus.
ABSTRACT Drought is one of the primary environmental constraints limiting poplar growth. Identifying key drought‐resistance genes and their regulatory mechanisms is crucial for genetic improvement of drought tolerance in poplar. Time‐course transcriptome analysis of 84K poplar ( Populus alba × P. glandulosa ) under drought stress revealed that the ERF family is among the most responsive transcription factor families, and PagERF135A exhibited the most significant upregulation, suggesting a key regulatory role. Genome‐wide identification of the ERF family in 84K poplar identified 276 members, with expansion primarily through segmental duplication, and purifying selection dominated their evolution. PagERF135A is a nuclear‐localized transcription factor with transcriptional activation activity. Overexpression of PagERF135A reduced drought tolerance in transgenic poplars, manifested by aggravated oxidative damage, diminished osmotic adjustments, and impaired PSII and PSI activities. Integrated transcriptomic and WGCNA analyses showed that PagERF135A overexpression suppressed drought‐induced expression of soluble sugar synthesis genes in starch‐sucrose metabolism, down‐regulated brassinosteroid biosynthesis and signaling genes, and promoted catabolic genes. Thus, PagERF135A negatively regulates drought tolerance by disrupting carbon metabolic flow and brassinosteroid signaling homeostasis. Our findings provide new insights into ERF‐mediated drought response mechanisms in poplar.
ABSTRACT Ocimum species are widely recognised for their diverse metabolic profiles, and recent multi‐omics studies have substantially advanced the characterisation of their non‐volatile metabolites. However, organic acids have not been systematically compared across Ocimum species using integrated metabolomic and transcriptomic approaches. Here, widely targeted metabolomics was used to profile organic acids across 10 accessions of four Ocimum species, identifying 70 compounds, 52 of which were common to all examined accessions. Leaf trait variation was observed among accessions, but morphological clustering diverged from species taxonomy, indicating phenotypic plasticity, whereas organic acid profiles showed clearer species‐ and accession‐level differentiation. The two O. gratissimum accessions examined here lacked α‐ketoglutaric and chelidonic acids and accumulated unique metabolites, while the two O . × africanum accessions showed hybrid‐specific enrichment of Subclass 2 metabolites. Transcriptomic integration revealed jasmonic acid pathway expression differences generally associated with the accumulation of tuberonic acid glucoside and 12‐hydroxyjasmonic acid glucoside. Notably, accession G144 showed high tuberonic acid glucoside accumulation despite low expression of core pathway genes, indicating that transcript abundance alone cannot fully explain metabolite levels and that additional post‐transcriptional or enzyme‐level regulation may be involved, a possibility requiring further experimental validation. This work provides a comprehensive organic acid profile of Ocimum , highlighting jasmonate derivatives as candidate species‐ or accession‐level markers and offering a framework for understanding organic acid diversification, while broader genus‐wide validation is required.
