Ring-shaped chalkiness increased by dry wind in rice : Direct measurement of turgor in endosperm cells and the role of osmotic adjustment at low water potential

灌浆过程中，丰风引起的干风增加了水稻的环状白垩粒。本研究的目的是利用改进的细胞压力探针，从生理学角度探讨生长中的胚乳细胞中环状白垩的发生机制。在白垩形成之前，即使在低水势条件下，内胚乳细胞也通过渗透调节在空间上保持膨润，而环状白垩的频率最高。结果还表明，最终粒重和籽粒中^<13> C分布均未减少。综上所述，通过渗透调节维持膨润有助于膨化水分亏缺条件下的籽粒发育，渗透调节可以暂时抑制淀粉在胚乳中的积累，导致膨化水分亏缺条件下籽粒呈环状白垩质。

Foehn-induced dry wind during grain filling typically increased ring-shaped chalky kernels in rice(Oryza sativa L.) plants. The objective of this study was to physiologically investigate mechanisms of the occurrence of ring-shaped chalkiness in the growing endosperm cells by utilizing the improved cell pressure probe. The inner endosperm cells, where the highest frequency of ring-shaped chalkiness was observed, maintained turgor by osmotic adjustment spatially even at low water potentials prior to the chalky formation. The results also indicated that neither the final grain weight nor^<13> C distribution in both panicles and the kernels was declined. Therefore, it was concluded that turgor maintenance by osmotic adjustment contributes to grain development under water deficit by foehn, and osmotic adjustment has a role in temporally inhibiting starch accumulation in endosperms, resulting in ring-shaped chalky kernels under foehn-induced water deficit conditions.