Nutrient accumulation and transcriptome patterns during grain development in rice

Abstract

Rice is an important source of calories and mineral nutrients for more than half of the world's population. The accumulation of essential and toxic mineral elements in rice grain affects its nutritional quality and safety. However, the patterns and processes by which different elements progressively accumulate during grain filling remain largely unknown. In the present study, we investigated temporal changes in dry matter, elemental concentrations, and the transcriptome in the grain of field-grown rice. We also investigated the effects of seed setting rate and the position of grain within rice panicle on element accumulation. Three different patterns of accumulation were observed: (i) elements including K, Mn, B, and Ca showed an early accumulation pattern; (ii) dry matter and elements including N, P, S, Mg, Cu, Zn, Mo, As, and Cd showed a mid-accumulation pattern; and (iii) elements such as Fe showed a gradual increase pattern. These different accumulation patterns can be explained by the differences in the biogeochemical behavior of the various elements in the soil, as well as differences in plant nutrient redistribution, gene expression, and the sink-source relationship. These results improve our knowledge of the dynamics of elemental accumulation in rice grain and are helpful for identification of functional genes mediating the translocation of elements to grain.

Cadmium accumulation dynamics in the rice endosperm during grain filling revealed by autoradiography

“…Finally, before the grain matured completely, Zn in the center of the endosperm was thought to be loaded to the embryo along with the water flow. Thus, Zn distributed almost uniformly in the mature rice endosperm and highly accumulated in the embryo, which is consistent with the elemental distribution maps visualized by synchrotron X-ray fluorescence microscopy (Gu et al, 2020;Johnson et al, 2011;Oli et al, 2016;Ren et al, 2023).…”

“…The actual amount of Cd accumulated in the endosperm during grain maturation in this study can not be quantitatively evaluated by the reason mentioned above. However, previous reports showed that the amount of Cd accumulated in a growing rice grain within 1 day peaked at around 9 DAF (Ren et al, 2023), and half of Cd in rice grains was loaded within 10 days after flowering (Rodda et al, 2011). The reduction of water flow into the endosperm after 10 DAF can be also suggested based on the MR images (Horigane et al, 2001).…”

Potassium transporter OsHAK9 regulates seed germination under salt stress by preventing gibberellin degradation through mediating OsGA2ox7 in rice

“…Therefore, one can envisage a scenario when higher accumulation of Na + in the OsHAK9 gain‐of‐function lines may be even beneficial for osmotic adjustment and turgor maintenance in some of them, assuming cytosolic Na + toxicity may be avoided. More interesting, one recent report showed that OsHAK9 expression pattern was highly expressed during grain development stage, and contributed to K + accumulation during seed filling (Ren et al, 2023), which could be beneficial for seed germination. Altogether, our study suggesting that OsHAK9 improves seed K + nutrition/homeostasis and reduces salt‐induced K + loss, most likely by balancing depolarization‐activated K + loss through the GORK (gated outwardly rectifying K + ) channel (Shabala and Pottosin, 2014; Wu et al, 2018).…”

Comprehensive analysis of physiological and metabolomic responses to drought reveals specific modulation of acquired tolerance mechanisms in rice

“…The major challenge of global agriculture is to increase food production with limited arable land and depleted water resources to meet the needs of growing populations. Among food crops, rice ( Oryza sativa L.) constitutes the largest source of calories in human diet for around 80% of the Asian population and for about 50% of the world (Ren et al, 2022). Therefore, sustaining rice production is essential to remain food and nutrient secure in these regions.…”