Fine Mapping of Five Grain Size QTLs Which Affect Grain Yield and Quality in Rice.

Grain size is a quantitative trait with a complex genetic mechanism, characterized by the combination of grain length (GL), grain width (GW), length to width ration (LWR), and grain thickness (GT). In this study, we conducted quantitative trait loci (QTL) analysis to investigate the genetic basis of grain size using BC1F2 and BC1F2:3 populations derived from two indica lines, Guangzhan 63-4S (GZ63-4S) and TGMS29 (core germplasm number W240). A total of twenty-four QTLs for grain size were identified, among which, three QTLs (qGW1, qGW7, and qGW12) controlling GL and two QTLs (qGW5 and qGL9) controlling GW were validated and subsequently fine mapped to regions ranging from 128 kb to 624 kb. Scanning electron microscopic (SEM) analysis and expression analysis revealed that qGW7 influences cell expansion, while qGL9 affects cell division. Conversely, qGW1, qGW5, and qGW12 promoted both cell division and expansion. Furthermore, negative correlations were observed between grain yield and quality for both qGW7 and qGW12. Nevertheless, qGW5 exhibited the potential to enhance quality without compromising yield. Importantly, we identified two promising QTLs, qGW1 and qGL9, which simultaneously improved both grain yield and quality. In summary, our results laid the foundation for cloning these five QTLs and provided valuable resources for breeding rice varieties with high yield and superior quality.

QTL detection for rice grain storage protein content and genetic effect verifications.

Rice grain quality is a multifarious attribute mainly governed by multiple nutritional factors. Grain protein is the central component of rice grain nutrition dominantly affecting eating-cooking qualities. Grain protein content is quantitatively influenced by its protein fractions. Genetic quantification of five protein fractions-albumins, globulins, prolamins, glutelin, and grain protein content-were evaluated by exploiting two BC3F2 mapping populations, derived from Kongyu131/TKM9 (population-I) and Kongyu131/Bg94-1 (population-II), which were grown in a single environment. Correlation studies among protein fractions and grain protein content were thoroughly investigated. A genetic linkage map was developed by using 146 single sequence repeat (SSR) markers in population-I and 167 markers in population-II. In total, 40 QTLs were delineated for five traits in both populations. Approximately 22 QTLs were dissected in population-I, derived from Kongyu131/TKM9, seven QTLs for albumin content, four QTLs for globulin content, three QTLs for prolamin content, four QTLs for glutelin content, and four QTLs for grain protein content. In total, 18 QTLs were detected in population-II, derived from Kongyu131/Bg94-1, five QTLs for albumin content, three QTLs for globulin content, four QTLs for prolamin content, two QTLs for glutelin content, and four QTLs for grain protein content. Three QTLs, qAlb7.1, Alb7.2, and qGPC7.2, derived from population-II (Kongyu131/Bg94-1) for albumin and grain protein content were successfully validated in the near isogenic line (NIL) populations. The localized chromosomal locus of the validated QTLs could be helpful for fine mapping via map-based cloning to discover underlying candidate genes. The functional insights of the underlying candidate gene would furnish novel perceptivity for the foundation of rice grain protein content and trigger the development of nutritionally important rice cultivars by combining marker-assisted selection (MAS) breeding. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-023-01436-7.

FLOURY ENDOSPERM19 encoding a class I glutamine amidotransferase affects grain quality in rice.

As a staple food for more than half of the world's population, the importance of rice is self-evident. Compared with ordinary rice, rice cultivars with superior eating quality and appearance quality are more popular with consumers due to their unique taste and ornamental value, even if their price is much higher. Appearance quality and CEQ (cooking and eating quality) are two very important aspects in the evaluation of rice quality. Here, we performed a genome-wide association study on floury endosperm in a diverse panel of 533 cultivated rice accessions. We identified a batch of potential floury genes and prioritize one (LOC_Os03g48060) for functional analyses. Two floury outer endosperm mutants (flo19-1 and flo19-2) were generated through editing LOC_Os03g48060 (named as FLO19 in this study), which encodes a class I glutamine amidotransferase. The different performances of the two mutants in various storage substances directly led to completely different changes in CEQ. The mutation of FLO19 gene caused the damage of carbon and nitrogen metabolism in rice, which affected the normal growth and development of rice, including decreased plant height and yield loss by decreased grain filling rate. Through haplotype analysis, we identified a haplotype of FLO19 that can improve both CEQ and appearance quality of rice, Hap2, which provides a selection target for rice quality improvement, especially for high-yield indica rice varieties. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-021-01226-z.

Molybdenum-induced effects on leaf ultra-structure and rhizosphere phosphorus transformation in Triticum aestivum L.

Soil phosphorus (P) occurs in pools of lower availability due to soil P fixation and therefore, it is a key constrain to crop production. Long term molybdenum-induced effects in wheat and rhizosphere/non-rhizosphere soil P dynamics have not yet been investigated. Here, a long term field experiment was conducted to explore these effects in wheat consisting of two treatments i.e. with molybdenum (+Mo) and without molybdenum (-Mo). The results revealed that molybdenum (Mo) supply increased plant biomass, grain yield, P uptake, preserved the configuration of chloroplast, stomata, and mesophyll tissue cells, suggesting the complementary effects of Mo on wheat yield and P accumulation. During the periods of vegetative growth, soil organic carbon, organic matter, and microbial biomass P were higher and tended to decrease in rhizosphere soil at maturity stage. In +Mo treatment, the most available P fractions [H2O-Pi (16.2-22.9 mg/kg and 4.24-7.57 mg/kg) and NaHCO3-Pi (130-149 mg/kg and 77.2-88 mg/kg)] were significantly increased in rhizosphere and non-rhizosphere soils, respectively. In addition, the +Mo treatment significantly increased the acid phosphatase activity and the expression of phoN/phoC, aphA, olpA/lppC gene transcripts in rhizosphere soil compared to -Mo. Our research findings suggested that Mo application has increased P availability not only through biochemical and chemical changes in rhizosphere but also through P assimilation and induced effects in the leaf ultra-structures. So, it might be a strategy of long term Mo fertilizer supply to overcome the P scarcity in plants and rhizosphere soil.

Metabolic and Proteomic Perspectives of Augmentation of Nutritional Contents and Plant Defense in Vigna unguiculata.

The current study enlists metabolites of Alstonia scholaris with bioactivities, and the most active compound, 3-(1-methylpyrrolidin-2-yl) pyridine, was selected against Macrophomina phaseolina. Appraisal of the Alstonia metabolites identified the 3-(1-methylpyrrolidin-2-yl) pyridine as a bioactive compound which elevated vitamins and nutritional contents of Vigna unguiculata up to ≥18%, and other physiological parameters up to 28.9%. The bioactive compound (0.1%) upregulated key defense genes, shifted defense metabolism from salicylic acid to jasmonic acid, and induced glucanase enzymes for improved defenses. The structural studies categorized four glucanase-isozymes under beta-glycanases falling in (Trans) glycosidases with TIM beta/alpha-barrel fold. The study determined key-protein factors (Q9SAJ4) for elevated nutritional contents, along with its structural and functional mechanisms, as well as interactions with other loci. The nicotine-docked Q9SAJ4 protein showed a 200% elevated activity and interacted with AT1G79550.2, AT1G12900.1, AT1G13440.1, AT3G04120.1, and AT3G26650.1 loci to ramp up the metabolic processes. Furthermore, the study emphasizes the physiological mechanism involved in the enrichment of the nutritional contents of V. unguiculata. Metabolic studies concluded that increased melibiose and glucose 6-phosphate contents, accompanied by reduced trehalose (-0.9-fold), with sugar drifts to downstream pyruvate biosynthesis and acetyl Co-A metabolism mainly triggered nutritional contents. Hydrogen bonding at residues G.357, G.380, and G.381 docked nicotine with Q9SAJ4 and transformed its bilobed structure for easy exposure toward substrate molecules. The current study augments the nutritional value of edible stuff and supports agriculture-based country economies.