A dietary transition from refined to whole grains would optimize grain processing, reduce food loss and emissions, and increase food nutritional contents. The results of systematical analysis and calculations in our study show that the average processing loss rate of grains including rice, wheat, and maize is approximately 4.1% in China due to the refinement, equivalent to an annual loss of around 13.3 Mt of grains. Furthermore, the refining process significantly reduces the nutritional contents of rice (51.6%), wheat flour (55.4%), and corn products (80.4%) mainly resulting from the removal of dietary fiber, minerals, and vitamins in refined grains. Replacing refined grains with whole grains in diets would lower agricultural carbon emissions by 2.7%, reducing agricultural water use by 4.3%, and saving arable land by 1,972,607 ha. Total environmental footprint could be reduced by 35% to 79% under three proposed scenarios. These findings indicate that shifting toward whole grain-based diets by Chinese consumers could reduce food losses, enhance human health, and improve environmental sustainability. This approach offers a promising strategy for transitioning towards more resilient and sustainable agri-food systems, benefiting human and planetary health.

Plant male reproduction is a fine-tuned developmental process that is susceptible to stressful environments and influences crop grain yields. Phytohormone signaling functions in control of plant normal growth and development as well as in response to external stresses, but the interaction or crosstalk among phytohormone signaling, stress response, and male reproduction in plants remains poorly understood. Cross-species comparison among 514 stress-response transcriptomic libraries revealed that ms33-6038, a genic male sterile mutant deficient in the ZmMs33/ZmGPAT6 gene, displayed an excessive drought stress-like transcriptional reprogramming in anthers triggered mainly by disturbed jasmonic acid (JA) homeostasis. An increased level of JA appeared in ZmMs33-deficient anthers at both meiotic and post-meiotic stages and activated genes involved in JA biosynthesis and signaling as well as genes functioning in JA-mediated drought response. Excessive accumulation of JA elevated expression level of a gene encoding a WRKY transcription factor that activated the ZmMs33 promoter. These findings reveal a feedback loop of ZmMs33-JA-WRKY-ZmMs33 in controlling male sterility and JA-mediated stress response in maize, shedding light on the crosstalk of stress response and male sterility mediated by phytohormone homeostasis and signaling.

Plant cell elongation depends on well-defined gene regulations, adequate nutrients, and timely cell wall modifications. Anther size is positively correlated with the number and viability of pollen grains, while little is known about molecular mechanisms underlying anther cell elongation. Here, we found that properly activated cell elongation regulators at transcriptional levels in loss-of-function ZmMs33 mutant (ms33-6038) anthers failed to promote maize anther elongation. ZmMs33 deficiency disrupted metabolic homeostasis mainly by inhibiting both photosynthesis in anther endothecium and lipid accumulation in anther tapetum. Importantly, ms33-6038 anthers displayed ectopic, premature and excessive secondary cell wall thickening in anther middle layer, which constrained cell elongation structurally and blocked nutrient flows across different anther wall layers. The metabolic disorder was only found in ms33-6038 mutant rather than several representative male-sterility lines at transcriptional and post-translational levels. Collectively, the disordered metabolisms and blocked nutrient flows defeated the activated cell elongation regulators, and finally inhibited anther elongation and growth with a unique "idling effect" in ms33-6038 mutant.

Sugar metabolism plays an essential role in plant male reproduction. Defects in sugar metabolism during anther and pollen development often result in genic male sterility (GMS). In this review, we summarize the recent progresses of the sugar metabolism-related GMS genes and their roles during plant anther and pollen development, including callose wall and primexine formation, intine development, pollen maturation and starch accumulation, anther dehiscence, and pollen germination and tube growth. We predict 112 putative sugar metabolic GMS genes in maize based on bioinformatics and RNA-seq analyses, and most of them have peak expression patterns during middle or late anther developmental stages. Finally, we outline the potential applications of sugar metabolic GMS genes in crop hybrid breeding and seed production. This review will deepen our understanding on sugar metabolic pathways in controlling pollen development and male fertility in plants.

Anther development is a programmed biological process crucial to plant male reproduction. Genome-wide analyses on the functions of transcriptional factor (TF) genes and their microRNA (miRNA) regulators contributing to anther development have not been comprehensively performed in maize. Here, using published RNA-Seq and small RNA-Seq (sRNA-Seq) data from maize anthers at ten developmental stages in three genic male-sterility (GMS) mutants (ocl4, mac1, and ms23) and wild type W23, as well as newly sequenced maize anther transcriptomes of ms7-6007 and lob30 GMS mutants and their WT lines, we analyzed and found 1079 stage-differentially expressed (stage-DE) TF genes that can be grouped into six (premeiotic, meiotic, postmeiotic, premeiotic-meiotic, premeiotic-postmeiotic, and meiotic-postmeiotic clusters) expression clusters. Functional enrichment combined with cytological and physiological analyses revealed specific functions of genes in each expression cluster. In addition, 118 stage-DE miRNAs and 99 miRNA-TF gene pairs were identified in maize anthers. Further analyses revealed the regulatory roles of zma-miR319 and zma-miR159 as well as ZmMs7 and ZmLOB30 on ZmGAMYB expression. Moreover, ZmGAMYB and its paralog ZmGAMYB-2 were demonstrated as novel maize GMS genes by CRISPR/Cas9 knockout analysis. These results extend our understanding on the functions of miRNA-TF gene regulatory pairs and GMS TF genes contributing to male fertility in plants.