FIGURE 3.

(A) Nutrient translocation from source to sink and a road map highlighting events associated with seed filling in monocot (cereals). (A) Plant takes up essential nutrients from the soil including N (nitrogen), P (phosphorus), K (potassium), Fe (iron), Zn (zinc), etc., and assimilates carbohydrate (sucrose) through fixing atmospheric CO₂ via photosynthesis. During seed filling stage the matured leaves translocate assimilates to the developing seed (sink), whereas, nutrients especially N and other minerals are remobilized from the senescing leaves to the sink organ (developing grain). The role of hormones and cross talk between source and sink during seed filling; at seed filling stage, stress hormones serve as key factors, which control the autophagy and senescence, thus translocating the N-pool and the minerals from the senescing leaves to the grain/seed. Auxins and cytokinins are important and regulate the seed cell numbers and size, this controlling the sink strength. (B) In dicots, the seed development and filling is controlled through transcriptional regulation. Several transcription factors interact/overlap with each other and also involve hormonal control during this event, as indicated in the figure. ABA, abscisic acid; GA, gibberellic acid; T-6-P, trehalose-6-phosphate; LEC1, leafy cotyledon 1; ABI3, abscisic acid-insensitive 3; EEL, enhanced em level; fusca3, FUS3; SnRK1, SNF1-related protein kinase; SUS, sucrose synthase; SUTs, sucrose transporters; IVT, invertase; RSR1, rice starch regulator 1; SSP, seed storage protein.