The elimination of seed shattering was a crucial event during crop domestication. Improving and fine-tuning the regulation of this process will further enhance grain yield by avoiding seed losses during crop production. In this work, we identified the loss-of-shattering mutant suppression of shattering1 (ssh1) through a screen of mutagenized wild rice (Oryza rufipogon) introgression lines with naturally high shattering. Using the MutMap approach and transformation experiments, we isolated a genetic factor for seed shattering, SSH1, which is an allele of SUPERNUMERARY BRACT (SNB), a gene encoding a plant-specific APETALA2-like transcription factor. A C-to-A point mutation in the ninth intron of SNB altered the splicing of its messenger RNA, causing the reduced shattering of the ssh1 mutant by altering the development of the abscission layer and vascular bundle at the junction between the seed and the pedicel. Our data suggest that SNB positively regulates the expression of two rice REPLUMLESS orthologs, qSH1 and SH5. In addition, the ssh1 mutant had larger seeds and a higher grain weight, resulting from its increased elongation of the glume longitudinal cells. The further identification of favorable SNB alleles will be valuable for improving rice seed shattering and grain yield using molecular breeding strategies.

Grain number is an important factor in determining grain production of rice (Oryza sativa L.). The molecular genetic basis for grain number is complex. Discovering new genes involved in regulating rice grain number increases our knowledge regarding its molecular mechanisms and aids breeding programs. Here, we identified GRAINS NUMBER 2 (GN2), a novel gene that is responsible for rice grain number, from “Yuanjiang” common wild rice (O. rufipogon Griff.). Transgenic plants overexpressing GN2 showed less grain number, reduced plant height, and later heading date than control plants. Interestingly, GN2 arose through the insertion of a 1094-bp sequence from LOC_Os02g45150 into the third exon of LOC_Os02g56630, and the inserted sequence recruited its nearby sequence to generate the chimeric GN2. The gene structure and expression pattern of GN2 were distinct from those of LOC_Os02g45150 and LOC_Os02g56630. Sequence analysis showed that GN2 may be generated in the natural population of Yuanjiang common wild rice. In this study, we identified a novel functional chimeric gene and also provided information regarding the molecular mechanisms regulating rice grain number.

Agronomy practices aimed at wheat (Triticum aestivum L.) grain Zn biofortification are important to alleviate Zn deficiency in humans, especially for those resource-poor people owing to subsistence on diets dominated by cereal-based foods with low concentrations and bioavailability of Zn. To promote understanding of source-sink flow processes affecting biofortification of wheat with Zn, effects of different source/sink manipulations on grain Zn accumulation by wheat were examined in pot and field at two locations. Treatments included foliar applications of deionized water, sucrose, ZnSO₄, sucrose + Zn, defoliation, spike shading or partial removal of spikes. Results showed sucrose + Zn significantly increased grain Zn concentration more than Zn alone. Grain Zn concentration with sucrose + Zn averaged 66 mg kg^-1 for ‘Kenong 9204’ and 59 mg kg^-1 for ‘Liangxing 99’ in pot, and ranged from 42 to 58 mg kg^-1 for ‘Liangxing 99’, ‘Jinan 17’, ‘Jimai 20’, ‘Jimai 22’, and ‘Luyuan 502’ under field, approaching the field-grown target 60 mg kg^-1 proposed by World Health Organization. Molar ratios of phytic acid/Zn and phytic acid × Ca/Zn of ‘Jinan 17’, ‘Jimai 20’ or ‘Luyuan 502’ with sucrose + Zn were reduced to be < 15 and < 200, respectively, suggesting higher Zn bioavailability. Defoliation or spike shading decreased grain weight, Zn concentration and content. It is concluded that grain Zn accumulation of wheat can be affected by the source-sink relationship of Zn and/or carbohydrate, and the foliar spray ‘sucrose + Zn’ is recommended for increasing concentration and bioavailability of Zn in wheat grains.

Peanut (Arachis hypogaea L.), a vital oilseed and cash crop, faces yield limitations due to abiotic stresses. The 9-cis-epoxycarotenoid dioxygenase (NCED) enzyme, a key enzyme in abscisic acid (ABA) biosynthesis regulating plant development and stress responses, remains mechanistically uncharacterized in peanut abiotic stress tolerance. In this study, we isolated a novel gene, AhNCED4, from the salt-tolerant mutant M24. The expression of AhNCED4 was strongly induced by NaCl, PEG6000, and ABA in peanut huayu20. Overexpression of AhNCED4 enhanced salt and drought tolerance in Arabidopsis. Transgenic overexpression of AhNCED4 improved salt and stress resistance through upregulated ROS-scavenging genes superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) with elevated enzymatic activities while reducing malondialdehyde (MDA), superoxide anion (O²⁻), and hydrogen peroxide (H₂O₂) accumulation compared to wild-type plants. Further research showed that the chlorophyll fluorescence parameters of transgenic lines were significantly increased, while light damage was significantly reduced. These findings establish AhNCED4 as a critical regulator of stress adaptation and an excellent candidate gene for resistance breeding in peanut.

Peanut (Arachis hypogaea L.) is an important oilseed crop whose yield is threatened by various abiotic stresses. Glycosyltransferases are crucial for diverse plant functions, including the regulation of plant growth and development, biotic and abiotic stress response, and the biosynthesis of secondary metabolites. However, the mechanism of glycosyltransferases relates to abiotic stresses remains unclear in peanut. In this study, we isolated a novel gene, AhIRX7, from a salt-tolerant mutant of peanut. The expression of AhIRX7 was strongly induced by NaCl and PEG6000. Overexpression of AhIRX7 led to increased, whereas silenced of AhIRX7 resulted in decreased tolerance of peanut seedlings to salt and drought stresses. Compared to wild-type (WT), the overexpression lines showed significantly increased chlorophyll fluorescence parameters and reduced photodamage under salt and drought stress. Their activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were markedly enhanced, while the accumulation of superoxide anion (O^2-), hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) were significantly reduced. In contrast, AhIRX7-silenced lines exhibited opposite trends in SOD, POD, and CAT activities, as well as MDA accumulation. Consequently, overexpression of AhIRX7 improved the regulation of photosynthesis, the dynamics of stomatal opening and closing under salt and drought stress in Arabidopsis plants. Overall, this study indicated that AhIRX7 gene functions in enhancing drought and salt stresses in peanuts and Arabidopsis, which may serve as a candidate gene for use in improving abiotic stress resistance in crops.

Peanut breeding has passed through various stages, including traditional breeding, hybrid breeding, and molecular breeding. With the rapid development of information technology, biotechnology has also made great progress. The application of biotechnology in breeding mainly includes three aspects: molecular biology, genetic breeding, and transgenic breeding. With the rapid development of genome, transcriptome, proteome, metabolome, epigenome, and phenomics studies and Big Data technology, peanut breeding is also developing intelligent approaches. Compared with traditional breeding, smart breeding has the advantages of high efficiency, speed, and accuracy, and will become an inevitable trend of future breeding work. This chapter reviews the development of peanut breeding technology around the world, highlights the overview, research progress, and application of peanut smart breeding, and provides an outlook on the development trend of peanut smart breeding. Intelligent breeding technology effectively shortens breeding time, accelerates the pace of improvement, and increases efficiency, playing a crucial role in improving yield and quality and reducing production costs. <!----> <!----> <!----> <!---->