Development of rice cultivars bearing numerous spikelets by breeding approach to increase the yearly production of rice to approximately 800 million metric tons to feed the ever increasing population of the world accompanies poor grain filling in the inferior spikelets preventing achievement of the yield potential. As the initial stages of caryopses development are of much importance for grain filling, spatio-temporal expressions of the miRNAs were studied during these periods in the spikelets of a compact-panicle rice cultivar, Oryza sativa cv. Mahalaxmi, bearing numerous spikelets per panicle to understand the reason of poor grain filling at the level of the initial biochemical events. Differential expression of several known miRNAs between the superior and inferior spikelets suggested great difference in metabolism related to grain filling in the spikelets based on their spatial location on compact panicle. Expressions of five known and four novel miRNAs were validated by Northern. Their targets included the enzymes directly involved in starch biosynthesis like sucrose synthase, starch synthase and pullulanase, besides others. Spatio-temporal expression studies of these miRNAs in the spikelets of Mahalaxmi revealed a pattern of mostly a greater expression in the inferior spikelets compared with the superior ones concomitant with an inverse expression of the target genes, which was not observed in the lax-panicle cultivar Upahar. The study thus revealed that the grain filling in rice is greatly regulated by miRNAs, and these miRNAs or their target genes could be considered for biotechnological interventions for improving grain filling in the rice cultivars of interest.

通过育种方法开发具有众多小穗的水稻品种，使水稻的年产量增加到大约8亿吨，以供养世界上不断增长的人口，同时由于劣等小穗的籽粒灌浆能力差，阻碍了单产的实现。作为颖果发展的初始阶段是非常重视对灌浆，所述miRNA的时空表达在这些时段期间在一个紧凑的穗水稻品种的小穗数，进行了研究稻简历。马哈拉克西米（Mahalaxmi），每个穗上有许多小穗，以了解在最初的生化事件水平下籽粒填充不良的原因。上小穗和下小穗之间几种已知miRNA的差异表达表明，基于小穗在紧凑穗上的空间位置，与小穗中籽粒填充相关的新陈代谢有很大差异。Northern验证了五个已知的miRNA和四个新颖的​​miRNA的表达。他们的目标包括其他直接参与淀粉生物合成的酶，如蔗糖合酶，淀粉合酶和支链淀粉酶。这些Mahnaxmi小穗中的miRNA的时空表达研究表明，与优越的小穗相比，与目标基因的反向表达相比，下小穗中的表达主要是更大的模式，在松散穗型Upahar中没有观察到。因此，研究表明，miRNA极大地调节了水稻的籽粒充实，这些miRNA或它们的靶基因可考虑用于生物技术干预措施，以改善目标水稻品种的籽粒充实。