Ishimaru Tsutomu, Matsuda Toshiaki, Ohsugi Ryu, Yamagishi Tohru
Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo, Tokyo 113-8657, Japan. Corresponding author: email;
School of Agriculture, Ibaraki University, Ami, Ibaraki 300-0393, Japan.
Funct Plant Biol. 2003 Jan;30(11):1139-1149. doi: 10.1071/FP03122.
Rice caryopses show different patterns of grain filling depending on position within a panicle. Caryopses located on the upper primary rachis branches generally accumulate larger amounts of starch at maturity than caryopses located on the secondary rachis branches of the lower primary rachis. In this study, the former and latter types of caryopses were defined as superior and inferior caryopses, respectively. Superior caryopses elongated soon after flowering, whereas inferior caryopses hardly elongated and were morphologically stagnant until the first 4 d after flowering (DAF). However, once inferior caryopses began elongation, their morphological development was the same as superior caryopses until the middle stage of grain filling. Cell division of the inner integument ceased before endosperm cellularization, pericarp functioned as a transient starch storage tissue until endosperm accumulated starch, and endosperm cell number was determined concomitantly with nucellus disintegration. These results implied the coordinated development of the endosperm with maternal tissues. In addition, differences of inner-integument cell number and endosperm cell number were related to a difference of endosperm size between superior and inferior caryopses.
水稻颖果根据其在稻穗上的位置呈现出不同的籽粒灌浆模式。位于上部一次枝梗上的颖果在成熟时通常比位于下部一次枝梗的二次枝梗上的颖果积累更多的淀粉。在本研究中，前者和后者类型的颖果分别被定义为上位颖果和下位颖果。上位颖果在开花后不久就开始伸长，而下位颖果在开花后的前4天几乎不伸长且形态停滞。然而，一旦下位颖果开始伸长，其形态发育与上位颖果相同，直至籽粒灌浆中期。内珠被的细胞分裂在胚乳细胞化之前停止，果皮在胚乳积累淀粉之前作为临时淀粉储存组织发挥作用，胚乳细胞数量与珠心解体同时确定。这些结果表明胚乳与母体组织的协调发育。此外，内珠被细胞数量和胚乳细胞数量的差异与上位颖果和下位颖果之间胚乳大小的差异有关。
