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Life Science Research and Sustainable Development ISBN: 978-98-84663-33-9

phenotype of srs3 is a result of the reduction in cell length of the lemma. The SRS3 protein
contains a kinesin motor domain and a coiled-coil structure and is a member of the kinesin 13
subfamily (Kitagawa et al., 2010). The cell length of the lemma in srs5 mutants is shorter than that
in the wild type plants. A 1-bp substitution in the fourth exon of SRS5 is responsible for the
phenotype. SRS5 encodes alpha-tubulin and may regulate cell elongation in a pathway
independent from the BR signaling network.
Besides these other class of genes related to yield has been cloned such as, GRAIN SIZE
on chromosome 5 (GS5) is a major QTL affecting grain width, grain filling, and grain weight (Li
et al., 2011). It encodes a serine carboxypeptidase and functions as a positive regulator of grain
size. Analysis of genomic DNA sequences and promoter swaps in transgenic plants reveals that
nucleotide changes in three segments of the GS5 promoter seem to be responsible for the
variations in grain width (Li et al., 2011). Grain width 8 (GW8) was identified from a cross between
HXJ74 and Basmati385 as a major QTL affecting grain width and grain yield (Wang et al., 2012).
A recent gene-cloning project has revealed that GW8 encodes SQUAMOSA pro-moter-binding
protein-like 16, referred to as OsSPL16, which belongs to the protein family of SBP domain-con-
taining transcription factors. There are six polymorphisms in the DNA sequence of OsSPL16
between HXJ74 and Basmati385. Among them, a 10-bp deletion in the promot-er region has been
shown to be responsible for the slender grain trait of Basmati385 (Wang et al., 2012).
To explore the relationship between floral induction and yield formation and the
molecular mechanism ofpanicle development in rice, a novel mutant, ghd10, was identified from
japonica variety Wuyunjing 7 plants subjectedto ethyl methanesulfonate (EMS) treatment. Hu et
al.(2013)used the F2 segregation populations were used for a χ2 test. For map-based cloning, an
F2 segregation population for mapping derived from a cross between the ghd10 mutant and the
indica cultivar NJ06 was constructed to identify the gene in the mutants. The parents and 6,846
F2 individuals were planted in a paddy field, among which 978 with the mutant phenotype were
used to map theGhd10. The ghd10 mutant exhibited delayed flowering time, tall stalks
andincreased panicle length and primary branch number. Map-based cloning revealed that
Ghd10 encodes a transcriptionfactor with Cys-2/His-2-type zinc finger motifs. Ghd10 is
orthologous to INDETERMINATE1 (ID1), which promotesflowering in maize (Zea mays) and is
identical to the previously cloned genes Rice Indeterminate1 (RID1), Early heading date2 (Ehd2)
and OsId1. Ghd10 mutation has pleiotropic effects on grain yield, heading date and plant height
and functions like Ghd7 and Ghd8/DTH8. A longer vegetative growth period allows more
photosynthate(the source) to be transferred to grains, i.e., the sink capacity increases, after
flowering. When a plant has a large sink capacity and the flow between the sink and the source
is unimpeded, the yield formation potential increases. For genetic analysis to determine whether
a dominant or recessive, single or multiple gene controls the ghd10 phenotype, reciprocal crosses
between ghd10 and the japonica cultivars NIP, WYJ7 and CJ06 were conducted.
In recent year a QTL ghd10 has been cloned using mutant plant population on
chromosome 10. This was the QTL identified for plant height and panicle development in
Wuyunjing 7 mutant population. The markers k10-5 and k10-3cosegrigated with ghd10 (Hu et al.,
2013).Fujita et al. (2013) identified a gene, SPIKELET NUMBER (SPIKE), from a tropical japonica
rice landrace that enhances the grain productivity of indica cultivars through pleiotropic effects
on plant architecture. Map-based cloning revealed that SPIKE was identical to NARROW LEAF1
(NAL1), which has been reported to control vein pattern in leaf. Phenotypic analyses of a near-
isogenic line of a popular indica cultivar, IR64, and overexpressor lines revealed increases in

https://jesjalna.org/Zoology-Publications/index.html 43 Department of Zoology, J. E. S. College, Jalna