Limits...
Pre-anthesis ovary development determines genotypic differences in potential kernel weight in sorghum.

Yang Z, van Oosterom EJ, Jordan DR, Hammer GL - J. Exp. Bot. (2009)

Bottom Line: The aim of this study was to determine the stage in development at which genetic effects on potential kernel weight were realized, and to investigate the developmental mechanisms by which potential kernel weight is controlled in sorghum.Genotypic effects on meristem size, ovary volume, and kernel weight were all consistent with additive genetic control, suggesting that they were causally related.The pre-fertilization genetic control of kernel weight probably operated through the developing pericarp, which is derived from the ovary wall and potentially constrains kernel expansion.

View Article: PubMed Central - PubMed

Affiliation: The University of Queensland, School of Land, Crop and Food Sciences, Brisbane, Qld 4072, Australia.

ABSTRACT
Kernel weight is an important factor determining grain yield and nutritional quality in sorghum, yet the developmental processes underlying the genotypic differences in potential kernel weight remain unclear. The aim of this study was to determine the stage in development at which genetic effects on potential kernel weight were realized, and to investigate the developmental mechanisms by which potential kernel weight is controlled in sorghum. Kernel development was studied in two field experiments with five genotypes known to differ in kernel weight at maturity. Pre-fertilization floret and ovary development was examined and post-fertilization kernel-filling characteristics were analysed. Large kernels had a higher rate of kernel filling and contained more endosperm cells and starch granules than normal-sized kernels. Genotypic differences in kernel development appeared before stamen primordia initiation in the developing florets, with sessile spikelets of large-seeded genotypes having larger floret apical meristems than normal-seeded genotypes. At anthesis, the ovaries for large-sized kernels were larger in volume, with more cells per layer and more vascular bundles in the ovary wall. Across experiments and genotypes, there was a significant positive correlation between kernel dry weight at maturity and ovary volume at anthesis. Genotypic effects on meristem size, ovary volume, and kernel weight were all consistent with additive genetic control, suggesting that they were causally related. The pre-fertilization genetic control of kernel weight probably operated through the developing pericarp, which is derived from the ovary wall and potentially constrains kernel expansion.

Show MeSH
Branches of panicles collected at anthesis showing genotypic difference in spikelet size. From left to right: KS115, ATx642/KS115, and ATx642/RQL36.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC2657540&req=5

fig6: Branches of panicles collected at anthesis showing genotypic difference in spikelet size. From left to right: KS115, ATx642/KS115, and ATx642/RQL36.

Mentions: The large ovary volume of KS115 was mainly due to the presence of more cells per layer in the ovary wall (Fig. 4C, D). In addition, the vascular supply to each ovary differed significantly among genotypes (Table 2; Fig. 4A, B). Ovaries of KS115 had 5–6 vascular bundles in their wall, including a right and a left stylar bundle, whereas ovaries of normal-seeded genotypes had only 2–3 vascular bundles in the ovary wall, including the stylar bundles. In both experiments, the number of vascular bundles for ATx642/KS115 (4.0–4.1) was close to the mean of KS115 and the normal-seeded genotypes (3.9–4.0). Within experiments, the number of vascular bundles was significantly related to the kernel-filling rate (r2=0.98, P <0.001 for Experiment I), but unlike ovary volume and kernel-filling rate, the number of vascular bundles was similar across the two experiments (Table 2). The size of other floral organs of the spikelets (i.e. glumes, lemma, and palea) also differed among genotypes. Those that produced large kernels had large floral organs (Fig. 6) and genotypic differences in the size of these organs became evident shortly after their initiation (data not shown).


Pre-anthesis ovary development determines genotypic differences in potential kernel weight in sorghum.

Yang Z, van Oosterom EJ, Jordan DR, Hammer GL - J. Exp. Bot. (2009)

Branches of panicles collected at anthesis showing genotypic difference in spikelet size. From left to right: KS115, ATx642/KS115, and ATx642/RQL36.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2657540&req=5

fig6: Branches of panicles collected at anthesis showing genotypic difference in spikelet size. From left to right: KS115, ATx642/KS115, and ATx642/RQL36.
Mentions: The large ovary volume of KS115 was mainly due to the presence of more cells per layer in the ovary wall (Fig. 4C, D). In addition, the vascular supply to each ovary differed significantly among genotypes (Table 2; Fig. 4A, B). Ovaries of KS115 had 5–6 vascular bundles in their wall, including a right and a left stylar bundle, whereas ovaries of normal-seeded genotypes had only 2–3 vascular bundles in the ovary wall, including the stylar bundles. In both experiments, the number of vascular bundles for ATx642/KS115 (4.0–4.1) was close to the mean of KS115 and the normal-seeded genotypes (3.9–4.0). Within experiments, the number of vascular bundles was significantly related to the kernel-filling rate (r2=0.98, P <0.001 for Experiment I), but unlike ovary volume and kernel-filling rate, the number of vascular bundles was similar across the two experiments (Table 2). The size of other floral organs of the spikelets (i.e. glumes, lemma, and palea) also differed among genotypes. Those that produced large kernels had large floral organs (Fig. 6) and genotypic differences in the size of these organs became evident shortly after their initiation (data not shown).

Bottom Line: The aim of this study was to determine the stage in development at which genetic effects on potential kernel weight were realized, and to investigate the developmental mechanisms by which potential kernel weight is controlled in sorghum.Genotypic effects on meristem size, ovary volume, and kernel weight were all consistent with additive genetic control, suggesting that they were causally related.The pre-fertilization genetic control of kernel weight probably operated through the developing pericarp, which is derived from the ovary wall and potentially constrains kernel expansion.

View Article: PubMed Central - PubMed

Affiliation: The University of Queensland, School of Land, Crop and Food Sciences, Brisbane, Qld 4072, Australia.

ABSTRACT
Kernel weight is an important factor determining grain yield and nutritional quality in sorghum, yet the developmental processes underlying the genotypic differences in potential kernel weight remain unclear. The aim of this study was to determine the stage in development at which genetic effects on potential kernel weight were realized, and to investigate the developmental mechanisms by which potential kernel weight is controlled in sorghum. Kernel development was studied in two field experiments with five genotypes known to differ in kernel weight at maturity. Pre-fertilization floret and ovary development was examined and post-fertilization kernel-filling characteristics were analysed. Large kernels had a higher rate of kernel filling and contained more endosperm cells and starch granules than normal-sized kernels. Genotypic differences in kernel development appeared before stamen primordia initiation in the developing florets, with sessile spikelets of large-seeded genotypes having larger floret apical meristems than normal-seeded genotypes. At anthesis, the ovaries for large-sized kernels were larger in volume, with more cells per layer and more vascular bundles in the ovary wall. Across experiments and genotypes, there was a significant positive correlation between kernel dry weight at maturity and ovary volume at anthesis. Genotypic effects on meristem size, ovary volume, and kernel weight were all consistent with additive genetic control, suggesting that they were causally related. The pre-fertilization genetic control of kernel weight probably operated through the developing pericarp, which is derived from the ovary wall and potentially constrains kernel expansion.

Show MeSH