Erect leaves caused by brassinosteroid deficiency increase biomass production and grain yield in rice

Abstract

New cultivars with very erect leaves, which increase light capture for photosynthesis and nitrogen storage for grain filling, may have increased grain yields. Here we show that the erect leaf phenotype of a rice brassinosteroid-deficient mutant, osdwarf4-1, is associated with enhanced grain yields under conditions of dense planting, even without extra fertilizer. Molecular and biochemical studies reveal that two different cytochrome P450s, CYP90B2/OsDWARF4 and CYP724B1/D11, function redundantly in C-22 hydroxylation, the rate-limiting step of brassinosteroid biosynthesis. Therefore, despite the central role of brassinosteroids in plant growth and development, mutation of OsDWARF4 alone causes only limited defects in brassinosteroid biosynthesis and plant morphology. These results suggest that regulated genetic modulation of brassinosteroid biosynthesis can improve crops without the negative environmental effects of fertilizers.

Rice leaf inclination2, a VIN3-like protein, regulates leaf angle through modulating cell division of the collar

“…Most of the identified mutants with altered leaf angles are related to the biosynthesis or signaling of the phytohormone brassinosteroids (BRs). Rice lamina joint angle increases proportionally to BR levels [11,12], and deficiency of OsDWARF4, a key gene in BR biosynthesis, resulted in increased leaf erectness and enhanced grain yields in dense planting [3]. The erect leaves were also observed in other BR biosynthesis-defective mutants including ebisu dwarf (d2, deficiency of CYD90D2/D2 [10]) and brassinosteroid-deficient dwarf1 (brd1, deficiency of OsDWARF [9]).…”

“…Quantitative analyses were carried out on the Rotor-Gene real-time thermocycler R3000 (Corbett Research) with Real-Time PCR Master Mix (Toyobo). The primers used were as follows: LC2 (5′-AGC ATC AGC TTT GGA CGA GGA-3′ and 5′-CAG TTG GTG GAA TAG AGC CAG AAT-3′), R2 (5′-TCT GCA CCT CCA CTT CGC TCA-3′ and 5′-TAG GTG GTG GCC TTG GAA GCT-3′), H3 (5′-AGC GAA GAG GAG ATG GCC CGT-3′ and 5′-AGG AGC TCC GTG CTC TTC TGG T-3′), CDKA;1 (5′-ATC ACG GCA ACA TCG TCA GG-3′ and 5′-AGT AAG CAA CGC CGC GGA GTA-3′), CDKA;2 (5′-ACC ACC GCA TAG TCA AAT CGT T-3′ and 5′-ACC ACA ATG TCA CCA CCT CGT GA-3′), XTR1 (5′-AGC CGT ACA TCC TGC AGA CGA-3′ and 5′-GCC CAG GTC CTT GCT GTT CT-3′), CPD1 (5′-TCT TCT CCA TCC CCT TTC CTC T-3′ and 5′-TCA AGA AGC TCC TCA ACC ATG T-3′ [44]), DWF4 (5′-AGT CGC GTG CTG CCA TTC T-3′ and 5′-AGC TCA GCA AGA GGT CCA GGA T-3′ [3]), BRI1 (5′-TAC CAG AGC TTC AGA TGC ACC A-3′ and 5′-AGT AGC TCA GGG TCG AAG ACA T-3′ [13]), OsGA2ox3 (5′-TTC TTC GTC AAC GTC GGC GAC TCG TTG C-3′ and 5′-TCT CAA ACT GGG CCA GCC TGT TGT CTC C-3′ [39]), OsGA20ox2 (5′-TAC TAC AGG GAG TTC TTC GCG GAC AGC A-3′ and 5′-TGT GCA GGC AGC TCT TAT ACC TCC CGT T-3′ [39]), OsIAA1 (5′-GCC GCT CAA TGA GGC ATT-3′ and 5′-GCT TCC ACT TTC TTT CAA TCC AA-3′ [40]), OsIAA9 (5′-AAG AAA ATG GCC AAT GAT GAT CA-3′ and 5′-CCC ATC ACC ATC CTC GTA GGT-3′ [40]), and OsIAA24 (5′-GGC TTG TGC TCT TCG TTG CT-3′ and 5′-CCT CTT GGA TTC AGA AAC ACT GAA-3′ [40]). …”

“…To date, several rice mutants with altered leaf inclination or QTLs related to lamina joint angle have been genetically identified [3,[7][8][9][10], and the major detected QTL for leaf angle is tiller angle 1 (ta1) [7,8]. However, the underlying mechanism of the leaf angle alteration has not been clarified.…”

“…It has been shown that an erectleaf trait in rice enhances the efficiency of sunlight capture and increases the nitrogen reservoirs for grain filling, and renders the plants more suitable for dense plantings [2,3].…”

QTLs for Shoot Length and Chlorophyll Content of Rice Seedlings Grown under Low-Temperature Conditions, using a Cross between Indica and Japonica Cultivars

“…4). On the other hand, the position corresponding to qSL3 contained several genes that caused dwarf phenotypes: OsDWARF4 (Sakamoto et al, 2006), LRK1 (Yang et al, 2013), d162(t) , OsAPC6 (Kumar et al, 2010) and SSD1 (Asano et al, 2010). Though these dwarf genes shorten the culm length of rice, qSL3 did not affect the culm length.…”