Spatial control of cell division by GA‐OsGRF7/8 module in a leaf explaining the leaf length variation between cultivated and wild rice

Abstract

Summary Cellular and genetic understanding of the rice leaf size regulation is limited, despite rice being the staple food of more than half of the global population. We investigated the mechanism controlling the rice leaf length using cultivated and wild rice accessions that remarkably differed for leaf size. Comparative transcriptomics, gibberellic acid (GA) quantification and leaf kinematics of the contrasting accessions suggested the involvement of GA, cell cycle and growth‐regulating factors (GRFs) in the rice leaf size regulation. Zone‐specific expression analysis and VIGS established the functions of specific GRFs in the process. The leaf length of the selected accessions was strongly correlated with GA levels. Higher GA content in wild rice accessions with longer leaves and GA‐induced increase in the leaf length via an increase in cell division confirmed a GA‐mediated regulation of division zone in rice. Downstream to GA, OsGRF7 and OsGRF8 function for controlling cell division to determine the rice leaf length. Spatial control of cell division to determine the division zone size mediated by GA and downstream OsGRF7 and OsGRF8 explains the leaf length differences between the cultivated and wild rice. This mechanism to control the rice leaf length might have contributed to optimizing leaf size during domestication.

SlZF3 regulates tomato plant height by directly repressing SlGA20ox4 in the gibberellic acid biosynthesis pathway

“…It was reported that leaf development was strongly correlated with GA levels. Leaf length can be regulated by the OsGRF7 (growth regulating factor 7)- and OsGRF8-mediated GA pathway [ 51 ], and exogenous GA3 can promote greater leaf area and thinner leaves [ 52 ]. Paraffin sections showed that the leaves of overexpressing plants were significantly thicker than those of AC, but were thinner for the RNAi lines ( Supplementary Data Fig.…”

Genome‑wide identification and characterization of miR396 family members and their target genes GRF in sorghum (Sorghum bicolor (L.) moench)

“…The phylogenetic analysis demonstrated that SbiGRF8 / 6 / 9 were clustered with OsGRF6 / 7 / 8 / 9 in Group I, highlighting their close phylogenetic relationship. Research in rice has demonstrated that OsGRF6 plays a vital role in regulating plant height, stem elongation, and floral organ development [ 31 , 35 ]; OsGRF7 mainly controls plant height, leaf length, and tiller number [ 13 , 29 ]; OsGRF8 regulates grain size and yield [ 33 ]; and OsGRF9 is not involved in rice growth and development regulation but regulates rice blast resistance [ 48 ]. Regarding expression analysis of SbiGRF s in different tissues and developmental stages, the expression level of SbiGRF8 was higher than that of other SbiGRF s in the young spikes of the inflorescence developmental stage and early development seeds.…”

Growth‐regulating factors: conserved and divergent roles in plant growth and development and potential value for crop improvement

“…Leaf length is tightly correlated with gibberellic acid (GA) levels. The GA–OsGRF7/OsGRF8 module controls the size of the leaf division zone, which is important for optimizing leaf size during domestication (Jathar et al., 2022). In maize, ectopic expression of the miR396 ‐resistant version of ZmGRF1 ( Zm‐rGRF1 ) increases the number of dividing cells in the division zone, thereby increasing leaf length (Nelissen et al., 2015).…”